The 100 most-cited articles in Journal of the American Chemical Society, 2023

The field of high entropy oxides (HEOs) flips traditional materials science paradigms on their head by seeking to understand what properties arise in the presence of profound configurational disorder. This disorder, which originates from multiple elements sharing a single lattice site, can take on a kaleidoscopic character due to the vast numbers of possible elemental combinations. High configurational disorder appears to imbue some HEOs with functional properties that far surpass their nondisordered analogs. While experimental discoveries abound, efforts to characterize the true magnitude of the configurational entropy and understand its role in stabilizing new phases and generating superior functional properties have lagged behind. Understanding the role of configurational disorder in existing HEOs is the crucial link to unlocking the rational design of new HEOs with targeted properties. In this Perspective, we attempt to establish a framework for articulating and beginning to address these questions in pursuit of a deeper understanding of the true role of entropy in HEOs.

High Resolution Image Download MS PowerPoint Slide Nitrogen-doped graphitic carbon materials hosting single-atom iron (Fe–N–C) are major non-precious metal catalysts for the oxygen reduction reaction (ORR). The nitrogen-coordinated Fe sites are described as the first coordination sphere. As opposed to the good performance in ORR, that in the oxygen evolution reaction (OER) is extremely poor due to the sluggish O–O coupling process, thus hampering the practical applications of rechargeable zinc (Zn)–air batteries. Herein, we succeed in boosting the OER activity of Fe–N–C by additionally incorporating phosphorus atoms into the second coordination sphere, here denoted as P/Fe–N–C. The resulting material exhibits excellent OER activity in 0.1 M KOH with an overpotential as low as 304 mV at a current density of 10 mA cm –2 . Even more importantly, they exhibit a remarkably small ORR/OER potential gap of 0.63 V. Theoretical calculations using first-principles density functional theory suggest that the phosphorus enhances the electrocatalytic activity by balancing the *OOH/*O adsorption at…

Transformation of biomass and plastic wastes to value-added chemicals and fuels is considered an upcycling process that is beneficial to resource utilization. Electrocatalysis offers a sustainable approach; however, it remains a huge challenge to increase the current density and deliver market-demanded chemicals with high selectivity. Herein, we demonstrate an electrocatalytic strategy for upcycling glycerol (from biodiesel byproduct) to lactic acid and ethylene glycol (from polyethylene terephthalate waste) to glycolic acid, with both products being as valuable monomers for biodegradable polymer production. By using a nickel hydroxide-supported gold electrocatalyst (Au/Ni(OH) 2 ), we achieve high selectivities of lactic acid and glycolic acid (77 and 91%, respectively) with high current densities at moderate potentials (317.7 mA/cm 2 at 0.95 V vs RHE and 326.2 mA/cm 2 at 1.15 V vs RHE, respectively). We reveal that glycerol and ethylene glycol can be enriched at the Au/Ni(OH) 2 interface through their adjacent hydroxyl groups, substantially increasing local concentrations and thus…

Dynamic reconstruction of catalyst active sites is particularly important for metal oxide-catalyzed oxygen evolution reaction (OER). However, the mechanism of how vacancy-induced reconstruction aids OER remains ambiguous. Here, we use Co 3 O 4 with Co or O vacancies to uncover the effects of different defects in the reconstruction process and the active motifs relevant to alkaline OER. Combining in situ characterization and theoretical calculations, we found that cobalt oxides are converted to an amorphous [Co(OH) 6 ] intermediate state, and then the mismatched rates of *OH adsorption and deprotonation lead to irreversible catalyst reconstruction. The stronger *OH adsorption but weaker deprotonation induced by O defects provides the driving force for reconstruction, while Co defects favor dehydrogenation and reduce the reconstruction rate. Importantly, both O and Co defects trigger highly OER-active bridge Co sites in reconstructed catalysts, of which Co defects induce a short Co–Co distance (3.38 Å) under compressive lattice stress and show the best OER activity (η 10 of 262 mV),…

We use prompt engineering to guide ChatGPT in the automation of text mining of metal-organic framework (MOF) synthesis conditions from diverse formats and styles of the scientific literature. This effectively mitigates ChatGPT's tendency to hallucinate information, an issue that previously made the use of large language models (LLMs) in scientific fields challenging. Our approach involves the development of a workflow implementing three different processes for text mining, programmed by ChatGPT itself. All of them enable parsing, searching, filtering, classification, summarization, and data unification with different trade-offs among labor, speed, and accuracy. We deploy this system to extract 26 257 distinct synthesis parameters pertaining to approximately 800 MOFs sourced from peer-reviewed research articles. This process incorporates our ChemPrompt Engineering strategy to instruct ChatGPT in text mining, resulting in impressive precision, recall, and F1 scores of 90-99%. Furthermore, with the data set built by text mining, we constructed a machine-learning model with over 87%…

Designing stable single-atom electrocatalysts with lower energy barriers is urgent for the acidic oxygen evolution reaction. In particular, the atomic catalysts are highly dependent on the kinetically sluggish acid–base mechanism, limiting the reaction paths of intermediates. Herein, we successfully manipulate the steric localization of Ru single atoms at the Co 3 O 4 surface to improve acidic oxygen evolution by precise control of the anchor sites. The delicate structure design can switch the reaction mechanism from the lattice oxygen mechanism (LOM) to the optimized adsorbate evolution mechanism (AEM). In particular, Ru atoms embedded into cation vacancies reveal an optimized mechanism that activates the proton donor–acceptor function (PDAM), demonstrating a new single-atom catalytic pathway to circumvent the classic scaling relationship. Steric interactions with intermediates at the anchored Ru–O–Co interface played a primary role in optimizing the intermediates’ conformation and reducing the energy barrier. As a comparison, Ru atoms confined to the surface sites exhibit a…

Two-dimensional covalent–organic frameworks (2D COFs) have recently emerged as great prospects for their applications as new photocatalytic platforms in solar-to-hydrogen conversion; nevertheless, their inefficient solar energy capture and fast charge recombination hinder the improvement of photocatalytic hydrogen production performance. Herein, two photoactive three-component donor−π–acceptor (TCDA) materials were constructed using a multicomponent synthesis strategy by introducing electron-deficient triazine and electron-rich benzotrithiophene moieties into frameworks through sp 2 carbon and imine linkages, respectively. Compared with two-component COFs, the novel TCDA-COFs are more convenient in regulating the inherent photophysical properties, thereby realizing outstanding photocatalytic activity for hydrogen evolution from water. Remarkably, the first sp 2 carbon-linked TCDA-COF displays an impressive hydrogen evolution rate of 70.8 ± 1.9 mmol g –1 h –1 with excellent reusability in the presence of 1 wt % Pt under visible-light illumination (420–780 nm). Utilizing the…

Electroreduction of nitrate to ammonia offers a promising pathway for nutrient recycling and recovery from wastewater with energy and environmental sustainability. There have been considerable efforts on the regulation of reaction pathways to facilitate nitrate-to-ammonia conversion over the competing hydrogen evolution reaction but only with limited success. Here, we report a Cu single-atom gel (Cu SAG) electrocatalyst that produces NH 3 from both nitrate and nitrite under neutral conditions. Given the unique mechanism of NO 2 – activation on Cu SAGs with spatial confinement and strengthened kinetics, a pulse electrolysis strategy is presented to cascade the accumulation and conversion of NO 2 – intermediates during NO 3 – reduction with the prohibited competition from the hydrogen evolution reaction, thus substantially enhancing the Faradaic efficiency and the yield rate for ammonia production compared with constant potential electrolysis. This work underlines the cooperative approach of the pulse electrolysis and SAGs with three-dimensional (3D) framework structures for highly…

Cu is a promising electrocatalyst in CO 2 reduction reaction (CO 2 RR) to high-value C 2+ products. However, as important C–C coupling active sites, the Cu + species is usually unstable under reduction conditions. How atomic dopants affect the performance of Cu-based catalysts is interesting to be studied. Herein, we first calculated the difference between the thermodynamic limiting potentials of CO 2 RR and the hydrogen evolution reaction, as well as the *CO binding energy over Cu 2 O doped with different metals, and the results indicated that doping atomic Gd into Cu 2 O could improve the performance of the catalyst effectively. On the basis of the theoretical study, we designed Gd 1 /CuO x catalysts. The distinctive electronic structure and large ion radii of Gd not only keep the Cu + species stable during the reaction but also induce tensile strain in Gd 1 /CuO x, resulting in excellent performance of the catalysts for electroreduction of CO 2 to C 2+ products. The Faradic efficiency of C 2+ products could reach 81.4% with a C 2+ product partial current density of 444.3 mA cm –2…

Multicomponent reactions (MCRs) can be used to introduce different functionalities into highly stable covalent organic frameworks (COFs). In this work, the irreversible three-component Doebner reaction is utilized to synthesize four chemically stable quinoline-4-carboxylic acid DMCR-COFs ( DMCR-1–3 and DMCR-1NH ) equipped with an acid–base bifunctionality. These DMCR-COFs show superior photocatalytic H 2 O 2 evolution (one of the most important industrial oxidants) compared to the imine COF analogue ( Imine-1 ). This is achieved with sacrificial oxidants but also in pure water and under an oxygen or air atmosphere. Furthermore, the DMCR-COFs show high photostability, durability, and recyclability. MCR-COFs thus provide a viable materials’ platform for solar to chemical energy conversion.

The acidic oxygen evolution reaction (OER) has long been the bottleneck of proton exchange membrane water electrolyzers given its harsh oxidative and corrosive environments. Herein, we suggest an effective strategy to greatly enhance both the acidic OER activity and stability of Co 3 O 4 spinel by atomic Ru selective substitution on the octahedral Co sites. The resulting highly symmetrical octahedral Ru–O–Co collaborative coordination with strong electron coupling effect enables the direct dioxygen radical coupling OER pathway. Indeed, both experiments and theoretical calculations reveal a thermodynamically breakthrough heterogeneous diatomic oxygen mechanism. Additionally, the active Ru–O–Co units are well-maintained upon the acidic OER thanks to the electron transfer from surrounding electron-enriched tetrahedral Co atoms via bridging oxygen bonds that suppresses the overoxidation and thus dissolution of active Ru and Co species. Consequently, the prepared catalyst, even with a low Ru mass loading of ca. 42.8 μg cm –2, exhibits an attractive acidic OER performance with a low…

The highly oxygen-dependent nature of photodynamic therapy (PDT) limits its therapeutic efficacy against hypoxic solid tumors in clinics, which is an urgent problem to be solved. Herein, we develop an oxygen-independent supramolecular photodynamic agent that produces hydroxyl radical ( • OH) by oxidizing water in the presence of intracellularly abundant pyruvic acid under oxygen-free conditions. A fluorene-substituted BODIPY was designed as the electron donor and coassembled with perylene diimide as the electron acceptor to form the quadruple hydrogen-bonded supramolecular photodynamic agent. Detailed mechanism studies reveal that intermolecular electron transfer and charge separation upon light irradiation result in an efficient generation of radical ion pairs. Under oxygen-free conditions, the cationic radicals directly oxidize water to generate highly cytotoxic • OH, and the anionic radicals transfer electrons to pyruvic acid, realizing the catalytic cycle. Thus, this photodynamic agent exhibited superb photocytotoxicity even under severe hypoxic environments and excellent in…

Synchronized conversion of CO 2 and H 2 O into hydrocarbons and oxygen via infrared-ignited photocatalysis remains a challenge. Herein, the hydroxyl-coordinated single-site Ru is anchored precisely on the metallic TiN surface by a NaBH 4 /NaOH reforming method to construct an infrared-responsive HO-Ru/TiN photocatalyst. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (ac-HAADF-STEM) and X-ray absorption spectroscopy (XAS) confirm the atomic distribution of the Ru species. XAS and density functional theory (DFT) calculations unveil the formation of surface HO-RuN 5 –Ti Lewis pair sites, which achieves efficient CO 2 polarization/activation via dual coordination with the C and O atoms of CO 2 on HO-Ru/TiN. Also, implanting the Ru species on the TiN surface powerfully boosts the separation and transfer of photoinduced charges. Under infrared irradiation, the HO-Ru/TiN catalyst shows a superior CO 2 -to-CO transformation activity coupled with H 2 O oxidation to release O 2, and the CO 2 reduction rate can further be promoted by about 3-fold…

Single-atom catalysts have been paid more attention to improving sluggish reaction kinetics and anchoring polysulfide for lithium–sulfur (Li–S) batteries. It has been demonstrated that d -block single-atom elements in the fourth period can chemically interact with the local environment, leading to effective adsorption and catalytic activity toward lithium polysulfides. Enlightened by theoretical screening, for the first time, we design novel single-atom Nb catalysts toward improved sulfur immobilization and catalyzation. Calculations reveal that Nb–N 4 active moiety possesses abundant unfilled antibonding orbitals, which promotes d-p hybridization and enhances anchoring capability toward lithium polysulfides via a “trapping–coupling–conversion” mechanism. The Nb– [email protected] cell exhibits a high capacity retention of over 85% after 1000 cycles, a superior rate performance of 740 mA h g –1 at 7 C, and a competitive areal capacity of 5.2 mAh cm –2 (5.6 mg cm –2 ). Our work provides a new perspective to extend cathodes enabling high-energy-density Li–S batteries.

Metal-free carbon-based materials are considered one of the most promising two-electron oxygen reduction reaction (2e – ORR) electrocatalysts for the green synthesis of hydrogen peroxide (H 2 O 2 ). However, most reported carbon electrocatalysts perform much more effectively in alkalis than in acids. Herein, by creatively using fullerene (C 60 ) as the precursor subject to ammonia treatment, we designed and synthesized a pentagonal defect-rich nitrogen-doped carbon nanomaterial (PD/N–C). It achieves outstanding ORR activity, 2e – selectivity, and stability in acidic electrolytes, surpassing the benchmark PtHg 4 alloy catalyst. Impressively, the flow cell based on the PD/N–C catalyst achieves nearly 100% Faraday efficiency with a remarkable H 2 O 2 yield, representing the best improvement among all the metal-free catalysts. Experimental and theoretical results reveal that such superb 2e – ORR performance of PD/N–C originates from the synergism between pentagonal defects and nitrogen dopants. This work presents an effective strategy for the design and construction of highly efficient…

Single atom catalysts (SACs) possess unique catalytic properties due to low-coordination and unsaturated active sites. However, the demonstrated performance of SACs is limited by low SAC loading, poor metal–support interactions, and nonstable performance. Herein, we report a macromolecule-assisted SAC synthesis approach that enabled us to demonstrate high-density Co single atoms (10.6 wt % Co SAC) in a pyridinic N-rich graphenic network. The highly porous carbon network (surface area of ∼186 m 2 g –1 ) with increased conjugation and vicinal Co site decoration in Co SACs significantly enhanced the electrocatalytic oxygen evolution reaction (OER) in 1 M KOH (η 10 at 351 mV; mass activity of 2209 mA mg Co –1 at 1.65 V) with more than 300 h stability. Operando X-ray absorption near-edge structure demonstrates the formation of electron-deficient Co-O coordination intermediates, accelerating OER kinetics. Density functional theory (DFT) calculations reveal the facile electron transfer from cobalt to oxygen species-accelerated OER.

Selective CH 4 oxidation to CH 3 OH or HCHO with O 2 in H 2 O under mild conditions provides a desired sustainable pathway for synthesis of commodity chemicals. However, manipulating reaction selectivity while maintaining high productivity remains a huge challenge due to the difficulty in the kinetic control of the formation of a desired oxygenate against its overoxidation. Here, we propose a highly efficient strategy, based on the precise control of the type of as-formed radicals by rational design on photocatalysts, to achieve both high selectivity and high productivity of CH 3 OH and HCHO in CH 4 photooxidation for the first time. Through tuning the band structure and the size of active sites ( i.e., single atoms or nanoparticles) in our Au/In 2 O 3 catalyst, we show alternative formation of two important radicals, • OOH and • OH, which leads to distinctly different reaction paths to the formation of CH 3 OH and HCHO, respectively. This approach gives rise to a remarkable HCHO selectivity and yield of 97.62% and 6.09 mmol g –1 on In 2 O 3 -supported Au single atoms (Au 1 /In 2 O…

Harvesting recyclable ammonia (NH 3 ) from the electrocatalytic reduction of nitrate (NO 3 RR) offers a sustainable strategy to close the ecological nitrogen cycle from nitration contamination in an energy-efficient and environmentally friendly manner. The emerging intermetallic single-atom alloys (ISAAs) are recognized to achieve the highest site density of single atoms by isolating contiguous metal atoms into single sites stabilized by another metal within the intermetallic structure, which holds promise to couple the catalytic benefits from intermetallic nanocrystals and single-atom catalysts for promoting NO 3 RR. Herein, ISAA In–Pd bimetallene, in which the Pd single atoms are isolated by surrounding In atoms, is reported to boost neutral NO 3 RR with a NH 3 Faradaic efficiency (FE) of 87.2%, a yield rate of 28.06 mg h –1 mg Pd –1, and an exceptional electrocatalytic stability with increased activity/selectivity over 100 h and 20 cycles. The ISAA structure induces substantially diminished overlap of Pd d-orbitals and narrowed p–d hybridization of In-p and Pd-d states around the…

Coupled photocatalysis without cocatalysts can maximize the utilization of photons and atoms, which puts forward higher demands on photocatalysts. Polymeric carbon nitride (CN) has become the most promising photocatalyst, but still suffers from major drawbacks of insufficient catalytic sites and low quantum efficiency. Herein, we report a fluid shear stress-assisted molecular assembly to prepare ultrathin-nanosheet-assembled acanthosphere-like CN (ASCN) with nitrogen vacancy (Nv) and carbonyl modification. Shear stress breaks the stacking interactions between layers and cuts the stacked structure into ultrathin layers, which are further reassembled into acanthosphere bundles driven by “centrifugal force”. Benefitted greatly from the ultrathin nature that provides more exposed active sites and improves charge carrier separation, ASCN-3 exhibits a 20-fold higher activity than the bulk counterpart toward oxygen reduction to H2O2 coupled with 4-methoxybenzyl alcohol (4-MBA) oxidation to anisaldehyde (AA), with significantly increased turnover frequency (TOF) values (TOF: 1.69 h–1 for…

The electrochemical CO 2 reduction reaction (CO 2 RR) using renewable electricity is one of the most promising strategies for reaching the goal of carbon neutrality. Multicarbonous (C 2+ ) products have broad applications, and ethanol is a valuable chemical and fuel. Many Cu-based catalysts have been reported to be efficient for the electrocatalytic CO 2 RR to C 2+ products, but they generally offer limited selectivity and current density toward ethanol. Herein, we proposed a silica-mediated hydrogen-bonded organic framework (HOF)-templated approach to preparing ultrahigh-density Cu single-atom catalysts (SACs) on thin-walled N-doped carbon nanotubes (TWN). The content of Cu in the catalysts prepared by this method could be up to 13.35 wt %. It was found that the catalysts showed outstanding performance for the electrochemical CO 2 RR to ethanol, and the Faradaic efficiency (FE) of ethanol increased with the increase in Cu–N 3 site density. The FE of ethanol over the catalysts with 13.35 wt % Cu could reach ∼81.9% with a partial current density of 35.6 mA cm –2 using an H-type cell,…

Although dispersing Pt atomic clusters (ACs) on a conducting support is a promising way to minimize the Pt amount required in hydrogen evolution reaction (HER), the catalytic mass activity and durability of Pt ACs are often unsatisfactory for alkaline HER due to their unfavorable water dissociation and challenges in stabilizing them against agglomeration and detachment. Herein, we report a class of single-atom Cr–N 4 sites with high oxophilicity interfaced with Pt ACs on mesoporous carbon for achieving a highly active and stable alkaline HER in an anion-exchange-membrane water electrolyzer (AEMWE). The as-made catalyst achieves the highest reported Pt mass activity (37.6 times higher than commercial Pt/C) and outstanding operational stability. Experimental and theoretical studies elucidate that the formation of a unique Pt–Cr quasi-covalent bonding interaction at the interface of Cr–N 4 sites and Pt ACs effectively suppresses the migration and thermal vibration of Pt atoms to stabilize Pt ACs and contributes to the greatly enhanced catalytic stability. Moreover, oxophilic Cr–N 4…

Abstract Cu-based electrocatalysts have great potential for facilitating CO2 reduction to produce energy-intensive fuels and chemicals. However, it remains challenging to obtain high product selectivity due to the inevitable strong competition among various pathways. Here, we propose a strategy to regulate the adsorption of oxygen-associated active species on Cu by introducing an oxophilic metal, which can effectively improve the selectivity of C2+ alcohols. Theoretical calculations manifested that doping of Lewis acid metal Al into Cu can affect the C–O bond and Cu–C bond breaking toward the selectively determining intermediate (shared by ethanol and ethylene), thus prioritizing the ethanol pathway. Experimentally, the Al-doped Cu catalyst exhibited an outstanding C2+ Faradaic efficiency (FE) of 84.5% with remarkable stability. In particular, the C2+ alcohol FE could reach 55.2% with a partial current density of 354.2 mA cm–2 and a formation rate of 1066.8 μmol cm–2 h–1. A detailed experimental study revealed that Al doping improved the adsorption strength of active oxygen species…

Large-current electrolysis of CO 2 to multi-carbon (C 2+ ) products is critical to realize the industrial application of CO 2 conversion. However, the poor binding strength of *CO intermediates on the catalyst surface induces multiple competing pathways, which hinder the C 2+ production. Herein, we report that p–d orbital hybridization induced by Ga-doped Cu (CuGa) could promote efficient CO 2 electrocatalysis to C 2+ products at ampere-level current density. It was found that CuGa exhibited the highest C 2+ productivity with a remarkable Faradaic efficiency (FE) of 81.5% at a current density of 0.9 A/cm 2, and the potential at such a high current density was −1.07 V versus reversible hydrogen electrode. At 1.1 A/cm 2, the catalyst still maintained a high C 2+ productivity with an FE of 76.9%. Experimental and theoretical studies indicated that the excellent performance of CuGa results from the p–d hybridization of Cu and Ga, which not only enriches reactive sites but also enhances the binding strength of the *CO intermediate and facilitates C–C coupling. The p–d hybridization…

The development of efficient photocatalysts for N 2 fixation to produce NH 3 under ambient conditions remains a great challenge. Since covalent organic frameworks (COFs) possess predesignable chemical structures, good crystallinity, and high porosity, it is highly significant to explore their potential for photocatalytic nitrogen conversion. Herein, we report a series of isostructural porphyrin-based COFs loaded with Au single atoms (COFX–Au, X = 1–5) for photocatalytic N 2 fixation. The porphyrin building blocks act as the docking sites to immobilize Au single atoms as well as light-harvesting antennae. The microenvironment of the Au catalytic center is precisely tuned by controlling the functional groups at the proximal and distal positions of porphyrin units. As a result, COF1–Au decorated with strong electron-withdrawing groups exhibits a high activity toward NH 3 production with rates of 333.0 ± 22.4 μmol g –1 h –1 and 37.0 ± 2.5 mmol g Au –1 h –1, which are 2.8- and 171-fold higher than that of COF4–Au decorated with electron-donating functional groups and a porphyrin–Au…

Acidic water electrolysis enables the production of hydrogen for use as a chemical and as a fuel. The acidic environment hinders water electrolysis on non-noble catalysts, a result of the sluggish kinetics associated with the adsorbate evolution mechanism, reliant as it is on four concerted proton-electron transfer steps. Enabling a faster mechanism with non-noble catalysts will help to further advance acidic water electrolysis. Here, we report evidence that doping Ba cations into a Co 3 O 4 framework to form Co 3– x Ba x O 4 promotes the oxide path mechanism and simultaneously improves activity in acidic electrolytes. Co 3– x Ba x O 4 catalysts reported herein exhibit an overpotential of 278 mV at 10 mA/cm 2 in 0.5 M H 2 SO 4 electrolyte and are stable over 110 h of continuous water oxidation operation. We find that the incorporation of Ba cations shortens the Co–Co distance and promotes OH adsorption, findings we link to improved water oxidation in acidic electrolyte.

Traditional computational approaches to design chemical species are limited by the need to compute properties for a vast number of candidates, e.g., by discriminative modeling. Therefore, inverse design methods aim to start from the desired property and optimize a corresponding chemical structure. From a machine learning viewpoint, the inverse design problem can be addressed through so-called generative modeling. Mathematically, discriminative models are defined by learning the probability distribution function of properties given the molecular or material structure. In contrast, a generative model seeks to exploit the joint probability of a chemical species with target characteristics. The overarching idea of generative modeling is to implement a system that produces novel compounds that are expected to have a desired set of chemical features, effectively sidestepping issues found in the forward design process. In this contribution, we overview and critically analyze popular generative algorithms like generative adversarial networks, variational autoencoders, flow, and diffusion…

The role of formate species for CO 2 hydrogenation is still under debate. Although formate has been frequently observed and commonly proposed as the possible intermediate, there is no definite evidence for the reaction of formate species for methanol production. Here, formate formation and conversion over the ZnZrO x solid solution catalyst are investigated by in situ/operando diffuse reflectance infrared Fourier transform spectroscopy-mass spectroscopy (DRIFTS-MS) coupled with density functional theory (DFT) calculations. Spectroscopic results show that bidentate carbonate formed from CO 2 adsorption is hydrogenated to formate on Zn–O–Zr sites (asymmetric sites), where the Zn site is responsible for H 2 activation and the Zr site is beneficial for the stabilization of reaction intermediates. The asymmetric Zn–O–Zr sites with adjacent and inequivalent features on the ZnZrO x catalyst promote not only formate formation but also its transformation. Both theoretical and experimental results demonstrate that the origin of the excellent performance of the ZnZrO x catalyst for methanol…

The concept of strain in organic compounds is as old as modern organic chemistry and was initially introduced to justify the synthetic setbacks along the synthesis of small ring systems ( pars construens of strain). In the last decades, chemists have developed an arsenal of strain-release reactions ( pars destruens of strain) which can generate─with significant driving force─rigid aliphatic systems that can act as three-dimensional alternatives to (hetero)arenes. Photocatalysis added an additional dimension to strain-release processes by leveraging the energy of photons to create chemical complexity under mild conditions. This perspective presents the latest advancements in strain-release photocatalysis─with emphases on mechanisms, catalytic cycles, and current limitations─the unique chemical architectures that can be produced, and possible future directions.

H 2 O 2 photosynthesis has attracted great interest in harvesting and converting solar energy to chemical energy. Nevertheless, the high-efficiency process of H 2 O 2 photosynthesis is driven by the low H 2 O 2 productivity due to the recombination of photogenerated electron–hole pairs, especially in the absence of a sacrificial agent. In this work, we demonstrate that ultrathin ZnIn 2 S 4 nanosheets with S vacancies (S v -ZIS) can serve as highly efficient catalysts for H 2 O 2 photosynthesis via O 2 /H 2 O redox. Mechanism studies confirm that S v in ZIS can extend the lifetimes of photogenerated carriers and suppress their recombination, which triggers the O 2 reduction and H 2 O oxidation to H 2 O 2 through radical initiation. Theoretical calculations suggest that the formation of S v can strongly change the coordination structure of ZIS, modulating the adsorption abilities to intermediates and avoiding the overoxidation of H 2 O to O 2 during O 2 /H 2 O redox, synergistically promoting 2e – O 2 reduction and 2e – H 2 O oxidation for ultrahigh H 2 O 2 productivity. The optimal…

Zinc metal batteries are strongly hindered by water corrosion, as solvated zinc ions would bring the active water molecules to the electrode/electrolyte interface constantly. Herein, we report a sacrificial solvation shell to repel active water molecules from the electrode/electrolyte interface and assist in forming a fluoride-rich, organic–inorganic gradient solid electrolyte interface (SEI) layer. The simultaneous sacrificial process of methanol and Zn(CF 3 SO 3 ) 2 results in the gradient SEI layer with an organic-rich surface (CH 2 OC– and C 5 product) and an inorganic-rich (ZnF 2 ) bottom, which combines the merits of fast ion diffusion and high flexibility. As a result, the methanol additive enables corrosion-free zinc stripping/plating on copper foils for 300 cycles with an average coulombic efficiency of 99.5%, a record high cumulative plating capacity of 10 A h/cm 2 at 40 mA/cm 2 in Zn/Zn symmetrical batteries. More importantly, at an ultralow N/P ratio of 2, the practical VO 2 //20 μm thick Zn plate full batteries with a high areal capacity of 4.7 mAh/cm 2 stably operate…

Copper (Cu) can efficiently catalyze the electrochemical CO 2 reduction reaction (CO 2 RR) to produce value-added fuels and chemicals, among which methane (CH 4 ) has drawn attention due to its high mass energy density. However, the linear scaling relationship between the adsorption energies of *CO and *CH x O on Cu restricts the selectivity toward CH 4 . Alloying a secondary metal in Cu provides a new freedom to break the linear scaling relationship, thus regulating the product distribution. This paper describes a controllable electrodeposition approach to alloying Cu with oxophilic metal (M) to steer the reaction pathway toward CH 4 . The optimized La 5 Cu 95 electrocatalyst exhibits a CH 4 Faradaic efficiency of 64.5%, with the partial current density of 193.5 mA cm –2 . The introduction of oxophilic La could lower the energy barrier for *CO hydrogenation to *CH x O by strengthening the M–O bond, which would also promote the breakage of the C–O bond in *CH 3 O for the formation of CH 4 . This work provides a new avenue for the design of Cu-based electrocatalysts to achieve high…

Electrocatalytic CO 2 reduction reaction (CO 2 RR) is one of the most promising routes to facilitate carbon neutrality. An alkaline electrolyte is typically needed to promote the production of valuable multi-carbon molecules (such as ethylene). However, the reaction between CO 2 and OH – consumes a significant quantity of CO 2 /alkali and causes the rapid decay of CO 2 RR selectivity and stability. Here, we design a catalyst–electrolyte interface with an effective electrostatic confinement of in situ generated OH – to improve ethylene electrosynthesis from CO 2 in neutral medium. In situ Raman measurements indicate the direct correlation between ethylene selectivity and the intensities of surface Cu–CO and Cu–OH species, suggesting the promoted C–C coupling with the surface enrichment of OH – . Thus, we report a CO 2 -to-ethylene Faradaic efficiency (FE) of 70% and a partial current density of 350 mA cm –2 at −0.89 V vs the reversible hydrogen electrode. Furthermore, the system demonstrated a 50 h stable operation at 300 mA cm –2 with an average ethylene FE of ∼68%. This study…

Exploring efficient strategies to overcome the performance constraints of oxygen evolution reaction (OER) electrocatalysts is vital for electrocatalytic applications such as H 2 O splitting, CO 2 reduction, N 2 reduction, etc . Herein, tunable, wide-range strain engineering of spinel oxides, such as NiFe 2 O 4, is proposed to enhance the OER activity. The lattice strain is regulated by interfacial thermal mismatch during the bonding process between thermally expanding NiFe 2 O 4 nanoparticles and the nonexpanding carbon fiber substrate. The tensile lattice strain causes energy bands to flatten near the Fermi level, lowering e g orbital occupancy, effectively increasing the number of electronic states near the Fermi level, and reducing the pseudoenergy gap. Consequently, the energy barrier of the rate-determining step for strained NiFe 2 O 4 is reduced, achieving a low overpotential of 180 mV at 10 mA/cm 2 . A total water decomposition voltage range of 1.52–1.56 V at 10 mA/cm 2 (without iR correction) was achieved in an asymmetric alkaline electrolytic cell with strained NiFe 2 O 4…

Electrochemical synthesis of ammonia via the nitrate reduction reaction (NO3RR) has been intensively researched as an alternative to the traditional Haber–Bosch process. Most research focuses on the low concentration range representative of the nitrate level in wastewater, leaving the high concentration range, which exists in nuclear and fertilizer wastes, unexplored. The use of a concentrated electrolyte (≥1 M) for higher rate production is hampered by poor hydrogen transfer kinetics. Herein, we demonstrate that a cocatalytic system of Ru/Cu 2 O catalyst enables NO3RR at 10.0 A in 1 M nitrate electrolyte in a 16 cm 2 flow electrolyzer, with 100% faradaic efficiency toward ammonia. Detailed mechanistic studies by deuterium labeling and operando Fourier transform infrared (FTIR) spectroscopy allow us to probe the hydrogen transfer rate and intermediate species on Ru/Cu 2 O. Ab initio molecular dynamics (AIMD) simulations reveal that adsorbed hydroxide on Ru nanoparticles increases the density of the hydrogen-bonded water network near the Cu 2 O surface, which promotes the hydrogen…

Oxygen reduction reaction (ORR) is essential to various renewable energy technologies. An important catalyst for ORR is single iron atoms embedded in nitrogen-doped graphene (Fe–N–C). However, the rate-limiting step of the ORR on Fe–N–C is unknown, significantly impeding understanding and improvement. Here, we report the activation energies of all of the steps, calculated by ab initio molecular dynamics simulations under constant electrode potential. In contrast to the common belief that a hydrogenation step limits the reaction rate, we find that the rate-limiting step is oxygen molecule replacing adsorbed water on Fe. This occurs through concerted motion of H 2 O desorption and O 2 adsorption, without leaving the site bare. Interestingly, despite being an apparent “thermal” process that is often considered to be potential-independent, the barrier reduces with the electrode potential. This can be explained by stronger Fe–O 2 binding and weaker Fe–H 2 O binding at a lower potential, due to O 2 gaining electrons and H 2 O donating electrons to the catalyst. Our study offers new…

Cobalt-based spinel oxides (i.e., Co 3 O 4 ) are emerging as low-cost and selective electrocatalysts for the electrochemical nitrate reduction reaction (NO 3 – RR) to ammonia (NH 3 ), although their activity is still unsatisfactory and the genuine active site is unclear. Here, we discover that the NO 3 – RR activity of Co 3 O 4 is highly dependent on the geometric location of the Co site, and the NO 3 – RR prefers to occur at octahedral Co (Co Oh ) rather than tetrahedral Co (Co Td ) sites. Moreover, Co Oh O 6 is electrochemically transformed to Co Oh O 5 along with the formation of O vacancies (O v ) during the process of NO 3 – RR. Both experimental and theoretic results reveal that in situ generated Co Oh O 5 –O v configuration is the genuine active site for the NO 3 – RR. To further enhance the activity of Co Oh sites, we replace inert Co Td with different contents of Cu 2+ cations, and a volcano-shape correlation between NO 3 – RR activity and electronic structures of Co Oh is observed. Impressively, in 1.0 M KOH, (Cu 0.6 Co 0.4 )Co 2 O 4 with optimized Co Oh sites achieves a…

Multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters are promising candidates for narrowband organic light-emitting diodes, but their electroluminescent performance is typically hindered by the slow reverse intersystem crossing rate ( k RISC ). Herein, we present an effective strategy to introduce a multichannel reverse intersystem crossing (RISC) pathway with large spin–orbit coupling by orthogonally linking an electron-donating unit to the MR framework. Through delicate manipulation of the excited-state energy levels, an additional intersegmental charge transfer triplet state could be “silently” induced without perturbing the MR character of the lowest excited singlet state. The proof-of-concept emitter CzBN3 not only affords 23-fold increase of k RISC compared with its prototypical MR skeleton but also realizes close-to-unity photoluminescence quantum yield, large radiative rate constant, and very narrow emission spectrum. These merits enable high maximum external quantum efficiency (EQE max ) of up to 37.1% and alleviated efficiency roll-off in the…

Lithium–sulfur (Li–S) batteries afford great promise on achieving practical high energy density beyond lithium-ion batteries. Lean-electrolyte conditions constitute the prerequisite for achieving high-energy-density Li–S batteries but inevitably deteriorates battery performances, especially the sulfur cathode kinetics. Herein, the polarizations of the sulfur cathode are systematically decoupled to identify the key kinetic limiting factor in lean-electrolyte Li–S batteries. Concretely, an electrochemical impedance spectroscopy combined galvanostatic intermittent titration technique method is developed to decouple the cathodic polarizations into activation, concentration, and ohmic parts. Therein, activation polarization during lithium sulfide nucleation emerges as the dominant polarization as the electrolyte-to-sulfur ratio (E/S ratio) decreases, and the sluggish interfacial charge transfer kinetics is identified as the main reason for degraded cell performances under lean-electrolyte conditions. Accordingly, a lithium bis(fluorosulfonyl)imide electrolyte is proposed to decrease…

Circularly polarized luminescence (CPL) is attracting much interest because it can carry extensive optical information. CPL shows left- or right-handedness and can be regarded as part of high-level visual perception to supply an extra dimension of information with regard to regular light. A key to meeting the needs for practical applications is to develop the emerging field of ultra-dissymmetric CPL. Chiral liquid crystal (LC) assemblies─otherwise referred to as cholesteric liquid crystals (CLCs)─are essentially organized helical superstructures with a highly ordered one-dimensional orientation, and distinctly superior to regular helical supramolecules. CLCs can achieve a perfect equilibrium of molecular short-range interaction and long-range orientational order, enabling molecule-scale chirality on a helical pitch and observable scale. LC assembly could be an ideal strategy for amplifying chirality, making it accessible to ultra-dissymmetric CPL. Herein, we focused on some basic but important issues regarding CPL: (i) How can CPL be created from chiral dyes? (ii) Is the chirality…

Photoredox catalysis of organic reactions driven by iron has attracted substantial attention throughout recent years, due to potential environmental and economic benefits. In this Perspective, three major strategies were identified that have been employed to date to achieve reactivities comparable to the successful noble metal photoredox catalysis: (1) Direct replacement of a noble metal center by iron in archetypal polypyridyl complexes, resulting in a metal-centered photofunctional state. (2) In situ generation of photoactive complexes by substrate coordination where the reactions are driven via intramolecular electron transfer involving charge-transfer states, for example, through visible-light-induced homolysis. (3) Improving the excited-state lifetimes and redox potentials of the charge-transfer states of iron complexes through new ligand design. We seek to give an overview and evaluation of recent developments in this rapidly growing field and, at the same time, provide an outlook on the future of iron-based photoredox catalysis.

How to optimize the enzyme-like catalytic activity of nanozymes to improve their applicability has become a great challenge. Herein, we present an l -cysteine ( l -Cys) coordination-driven self-assembly strategy to activate polyvinylpyrrolidone (PVP)-modified Cu single-atom nanozymes MoO x -Cu-Cys (denoted as MCCP SAzymes) aiming at catalytic tumor-specific therapy. The Cu single atom content of MCCP can be rationally modulated to 10.10 wt %, which activates the catalase (CAT)-like activity of MoO x nanoparticles to catalyze the decomposition of H 2 O 2 in acidic microenvironments to increase O 2 production. Excitingly, the maximized CAT-like catalytic efficiency of MCCP is 138-fold higher than that of typical MnO 2 nanozymes and exhibits 14.3-fold higher affinity than natural catalase, as demonstrated by steady-state kinetics. We verify that the well-defined l -Cys-Cu···O active sites optimize CAT-like activity to match the active sites of natural catalase through an l -Cys bridge-accelerated electron transfer from Cys-Cu to MoO x disclosed by density functional theory…

Developing low platinum-group-metal (PGM) catalysts for the oxygen reduction reaction (ORR) in proton-exchange membrane fuel cells (PEMFCs) for heavy-duty vehicles (HDVs) remains a great challenge due to the highly demanded power density and long-term durability. This work explores the possible synergistic effect between single Mn site-rich carbon (Mn SA -NC) and Pt nanoparticles, aiming to improve intrinsic activity and stability of PGM catalysts. Density functional theory (DFT) calculations predicted a strong coupling effect between Pt and MnN 4 sites in the carbon support, strengthening their interactions to immobilize Pt nanoparticles during the ORR. The adjacent MnN 4 sites weaken oxygen adsorption at Pt to enhance intrinsic activity. Well-dispersed Pt (2.1 nm) and ordered L1 2 -Pt 3 Co nanoparticles (3.3 nm) were retained on the Mn SA -NC support after indispensable high-temperature annealing up to 800 °C, suggesting enhanced thermal stability. Both PGM catalysts were thoroughly studied in membrane electrode assemblies (MEAs), showing compelling performance and durability. The…

Designing efficient and durable bifunctional catalysts for 5-hydroxymethylfurfural (HMF) oxidation reaction (HMFOR) and hydrogen evolution reaction (HER) is desirable for the co-production of biomass-upgraded chemicals and sustainable hydrogen, which is limited by the competitive adsorption of hydroxyl species (OH ads ) and HMF molecules. Here, we report a class of Rh–O 5 /Ni(Fe) atomic site on nanoporous mesh-type layered double hydroxides with atomic-scale cooperative adsorption centers for highly active and stable alkaline HMFOR and HER catalysis. A low cell voltage of 1.48 V is required to achieve 100 mA cm –2 in an integrated electrolysis system along with excellent stability (>100 h). Operando infrared and X-ray absorption spectroscopic probes unveil that HMF molecules are selectively adsorbed and activated over the single-atom Rh sites and oxidized by in situ-formed electrophilic OH ads species on neighboring Ni sites. Theoretical studies further demonstrate that the strong d–d orbital coupling interactions between atomic-level Rh and surrounding Ni atoms in the special Rh–O…

Benefiting from their unique structural merits, three-dimensional (3D) large-pore COF materials demonstrate high surface areas and interconnected large channels, which makes these materials promising in practical applications. Unfortunately, functionalization strategies and application research are still absent in these structures. To this end, a series of functional 3D stp -topologized COFs are designed based on porphyrin or metalloporphyrin moieties, named JUC-640-M (M = Co, Ni, or H). Interestingly, JUC-640-H exhibits a record-breaking low crystal density (0.106 cm 3 g –1 ) among all crystalline materials, along with the largest interconnected pore size (4.6 nm) in 3D COFs, high surface area (2204 m 2 g –1 ), and abundant exposed porphyrin moieties (0.845 mmol g –1 ). Inspired by the unique structural characteristics and photoelectrical performance, JUC-640-Co is utilized for the photoreduction of CO 2 to CO and demonstrates a high CO production rate (15.1 mmol g –1 h –1 ), selectivity (94.4%), and stability. It should be noted that the CO production rate of JUC-640-Co has…

Arming activatable mild-photothermal therapy (PTT) with the property of relieving tumor thermotolerance holds great promise for overcoming traditional mild PTT limitations such as thermoresistance, insufficient therapeutic effect, and off-target heating. Herein, a mitochondria-targeting, defect-engineered AFCT nanozyme with enhanced multi-enzymatic activity was elaborately designed as a tumor microenvironment (TME)-activatable phototheranostic agent to achieve remarkable anti-tumor therapy via “electron transport chain (ETC) interference and synergistic adjuvant therapy”. Density functional theory calculations revealed that the synergistic effect among multi-enzyme active centers endows the AFCT nanozymes with excellent catalytic activity. In TME, open sources of H 2 O 2 can be achieved by superoxide dismutase-mimicking AFCT nanozymes. In response to the dual stimuli of H 2 O 2 and mild acidity, the peroxidase-mimicking activity of AFCT nanozymes not only catalyzes the accumulation of H 2 O 2 to generate ·OH but also converts the loaded…

The photocatalytic conversion of CO 2 into C 2+ products such as ethylene is a promising path toward the carbon neutral goal but remains a big challenge due to the high activation barrier for CO 2 and similar reduction potentials of many possible multi-electron-transfer products. Herein, an effective tandem photocatalysis strategy has been developed to support conversion of CO 2 to ethylene by construction of the synergistic dual sites in rhenium-(I) bipyridine fac -[Re I (bpy)(CO) 3 Cl] (Re-bpy) and copper-porphyrinic triazine framework [PTF(Cu)]. With these two catalysts, a large amount of ethylene can be produced at a rate of 73.2 μmol g –1 h –1 under visible light irradiation. However, ethylene cannot be obtained from CO 2 by use of either component of the Re-bpy or PTF(Cu) catalysts alone; with a single catalyst, only monocarbon product CO is produced under similar conditions. In the tandem photocatalytic system, the CO generated at the Re-bpy sites is adsorbed by the nearby Cu single sites in PTF(Cu), and this is followed by a synergistic C–C coupling process which ultimately…

Aqueous zinc-ion batteries (AZIBs) are receiving increasing attention for power-grid energy storage systems. Nevertheless, warranting long-term reversible operation is not trivial owing to uncontrolled interfacial phenomena related to zinc dendritic growth and parasitic reactions. Herein, the addition of hexamethylphosphoramide (HMPA) to the electrolyte revealed the surface overpotential (|η s |) to be a key metric of the reversibility. HMPA adsorbs onto active sites on the zinc metal surface, raising the surface overpotential toward lowering the nucleation energy barrier and decreasing the critical size ( r crit ) of nuclei. We also correlated the observed interface-to-bulk properties by the Wagner (Wa) dimensionless number. The controlled interface enables a Zn|V 6 O 13 full cell to retain 75.97% capacity for 2000 cycles, with a capacity loss of only 1.5% after 72 h resting. Our study not only delivers AZIBs with unparalleled cycling and storage performance but also proposes surface overpotential as a key descriptor regarding the sustainability of AZIB cycling and storage.

The inert C( sp 3 )–H bond and easy overoxidation of toluene make the selective oxidation of toluene to benzaldehyde a great challenge. Herein, we present that a photocatalyst, constructed with a small amount (1 mol %) of amorphous BiOCl nanosheets assembled on TiO 2 (denoted as 0.01BOC/TiO 2 ), shows excellent performance in toluene oxidation to benzaldehyde, with 85% selectivity at 10% conversion, and the benzaldehyde formation rate is up to 1.7 mmol g –1 h –1, which is 5.6 and 3.7 times that of bare TiO 2 and BOC, respectively. In addition to the charge separation function of the BOC/TiO 2 heterojunction, we found that the amorphous structure of BOC endows its abundant surface oxygen vacancies (Ov), which can further promote the charge separation. Most importantly, the surface Ov of amorphous BOC can efficiently adsorb and activate O 2, and amorphous BOC makes the product, benzaldehyde, easily desorb from the catalyst surface, which alleviates the further oxidation of benzaldehyde, and results in the high selectivity. This work highlights the importance of the microstructure…

In nature, enzymatic reactions occur in well-functioning catalytic pockets, where substrates bind and react by properly arranging the catalytic sites and amino acids in a three-dimensional (3D) space. Single-atom nanozymes (SAzymes) are a new type of nanozymes with active sites similar to those of natural metalloenzymes. However, the catalytic centers in current SAzymes are two-dimensional (2D) architectures and the lack of collaborative substrate-binding features limits their catalytic activity. Herein, we report a dimensionality engineering strategy to convert conventional 2D Fe–N-4 centers into 3D structures by integrating oxidized sulfur functionalities onto the carbon plane. Our results suggest that oxidized sulfur functionalities could serve as binding sites for assisting substrate orientation and facilitating the desorption of H 2 O, resulting in an outstanding specific activity of up to 119.77 U mg –1, which is 6.8 times higher than that of conventional FeN 4 C SAzymes. This study paves the way for the rational design of highly active single-atom nanozymes.

Heterogeneous catalysts containing diatomic sites are often hypothesized to have distinctive reactivity due to synergistic effects, but there are limited approaches that enable the convenient production of diatomic catalysts (DACs) with diverse metal combinations. Here, we present a general synthetic strategy for constructing a DAC library across a wide spectrum of homonuclear (Fe 2, Co 2, Ni 2, Cu 2, Mn 2, and Pd 2 ) and heteronuclear (Fe–Cu, Fe–Ni, Cu–Mn, and Cu–Co) bimetal centers. This strategy is based on an encapsulation–pyrolysis approach, wherein a porous material-encapsulated macrocyclic complex mediates the structure of DACs by preserving the main body of the molecular framework during pyrolysis. We take the oxygen reduction reaction (ORR) as an example to show that this DAC library can provide great opportunities for electrocatalyst development by unlocking an unconventional reaction pathway. Among all investigated sites, Fe–Cu diatomic sites possess exceptional high durability for ORR because the Fe–Cu pairs can steer elementary steps in the catalytic cycle and suppress…

Covalent organic frameworks (COFs) hold the potential in converting CO 2 with water into value-added fuels and O 2 to save the deteriorating ecological environment. However, reaching high yield and selectivity is a grand challenge under metal-, photosensitizer-, or sacrificial reagent-free conditions. Here, inspired by microstructures of natural leaves, we designed triazine-based COF membranes with the integration of steady light-harvesting sites, efficient catalytic center, and fast charge/mass transfer configuration to fabricate a novel artificial leaf for the first time. Significantly, a record high CO yield of 1240 μmol g –1 in a 4 h reaction, approximately 100% selectivity, and a long lifespan (at least 16 cycles) were achieved under gas–solid conditions without using any metal, photosensitizer, or sacrificial reagent. Unlike the existing knowledge, the chemical structural unit of triazine-imide-triazine and the unique physical form of the COF membrane are predominant for such a remarkable photocatalysis. This work opens a new pathway to simulating photosynthesis in leaves and…

Sustainable conversion of plastic waste to mitigate environmental threats and reclaim waste value is important. Ambient-condition photoreforming is practically attractive to convert waste to hydrogen (H 2 ); however, it has poor performance because of mutual constraint between proton reduction and substrate oxidation. Here, we realize a cooperative photoredox using defect-rich chalcogenide nanosheet-coupled photocatalysts, e.g., d-NiPS 3 /CdS, to give an ultrahigh H 2 evolution of ∼40 mmol g cat –1 h –1 and organic acid yield up to 78 μmol within 9 h, together with excellent stability beyond 100 h in photoreforming of commercial waste plastic poly(lactic acid) and poly(ethylene terephthalate). Significantly, these metrics represent one of the most efficient plastic photoreforming reported. In situ ultrafast spectroscopic studies confirm a charge transfer-mediated reaction mechanism in which d-NiPS 3 rapidly extracts electrons from CdS to boost H 2 evolution, favoring hole-dominated substrate oxidation to improve overall efficiency. This work opens practical avenues for converting…

Strong metal–support interaction (SMSI) has been extensively studied in heterogeneous catalysis because of its significance in stabilizing active metals and tuning catalytic performance, but the origin of SMSI is not fully revealed. Herein, by using Pt/CeO 2 as a model catalyst, we report an embedding structure at the interface between Pt and (110) plane of CeO 2, where Pt clusters (∼1.6 nm) are embedded into the lattice of ceria within 3–4 atomic layers. In contrast, this phenomenon is absent in the CeO 2 (100) support. This unique geometric structure, as an effective motivator, triggers more significant electron transfer from Pt clusters to CeO 2 (110) support accompanied by the formation of interfacial structure (Pt δ + –O v –Ce 3+ ), which plays a crucial role in stabilizing Pt nanoclusters. A comprehensive investigation based on experimental studies and theoretical calculations substantiates that the interfacial sites serve as the intrinsic active center toward water–gas shift reaction (WGSR), featuring a moderate strength CO activation adsorption and largely decreased energy…

High-entropy oxides (HEOs), which contain five or more metal cations that are generally thought to be randomly mixed in a crystalline oxide lattice, can exhibit unique and enhanced properties, including improved catalytic performance, due to synergistic effects. Here, we show that band gap narrowing emerges in a high-entropy aluminate spinel oxide, (Fe 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 )Al 2 O 4 ( A 5 Al 2 O 4 ). The 0.9 eV band gap of A 5 Al 2 O 4 is narrower than the band gaps of all parent spinel oxides. First-principles calculations for multicomponent A Al 2 O 4 spinels indicate that the band gap narrowing arises from the broadening of the energy distribution of the 3d states due to variations in the electronegativities and crystal field splitting across the 3d transition-metal series. As a catalyst for the oxygen evolution reaction in an alkaline electrolyte, A 5 Al 2 O 4 reaches a current density of 10 mA/cm 2 at an overpotential of 400 mV, outperforming all of the single-metal end members at an applied potential of 1.7 V vs RHE. Catalyst deactivation occurs after 5 h at 10…

High Resolution Image Download MS PowerPoint Slide Electrolytes, consisting of salts, solvents, and additives, must form a stable solid electrolyte interphase (SEI) to ensure the performance and durability of lithium(Li)-ion batteries. However, the electric double layer (EDL) structure near charged surfaces is still unsolved, despite its importance in dictating the species being reduced for SEI formation near a negative electrode. In this work, a newly developed model was used to illustrate the effect of EDL on SEI formation in two essential electrolytes, the carbonate-based electrolyte for Li-ion batteries and the ether-based electrolyte for batteries with Li-metal anodes. Both electrolytes have fluoroethylene carbonate (FEC) as a common additive to form the beneficial F-containing SEI component ( e.g., LiF). However, the role of FEC drastically differs in these electrolytes. FEC is an effective SEI modifier for the carbonate-based electrolyte by being the only F-containing species entering the EDL and being reduced, as the anion (PF 6 – ) will not enter the EDL. For the…

Copper (Cu) is the only known material that can efficiently electrocatalyze CO 2 to value-added multicarbon products. Owing to the instability of the Cu δ+ state and microscopic structure in reactions, Cu catalysts are still facing big challenges with low selectivity and poor durability, particularly at high current densities. Herein, we report a rational one-step surface coordination approach for the synthesis of Cu dendrites with an ultrastable Cu δ+ state and hydrophobicity (Cu CF), even after exposure to air for over 6 months. As a result, Cu CF exhibited a C 2 FE of 90.6% at a partial current density of 453.3 mA cm –2 in a flow cell. A 400 h stable electrolysis at 800 mA and even a ground-breaking stable operation at a large industrial current of 10 A were achieved in the membrane electrode assembly (MEA) form. We further demonstrated a continuous production of C 2 H 5 OH solution with 90% relative purity at 600 mA over 50 h in a solid-electrolyte reactor. Spectroscopy and computation results suggested that Cu(II) carboxylate coordination species formed on the surface of Cu CF,…

Fashioning microporous covalent organic frameworks (COFs) into single crystals with ordered macropores allows for an effective reduction of the mass transfer resistance and the maximum preservation of their intrinsic properties but remains unexplored. Here, we report the first synthesis of three-dimensional (3D) ordered macroporous single crystals of the imine-linked 3D microporous COFs (COF-300 and COF-303) via a template-assisted modulated strategy. In this strategy, COFs crystallized within the sacrificial colloidal crystal template, assembled from monodisperse polystyrene microspheres, and underwent an aniline-modulated amorphous-to-crystalline transformation to form large single crystals with 3D interconnected macropores. The effects of the introduced macroporous structure on the sorption performances of COF-300 single crystals were further probed by iodine. Our results indicate that iodine adsorption occurred in micropores of COF-300 but not in the introduced macropores. Accordingly, the iodine adsorption capacity of COF single crystals was governed by their micropore…

Activating anionic redox chemistry in layered oxide cathodes is a paradigmatic approach to devise high-energy sodium-ion batteries. Unfortunately, excessive oxygen redox usually induces irreversible lattice oxygen loss and cation migration, resulting in rapid capacity and voltage fading and sluggish reaction kinetics. Herein, the reductive coupling mechanism (RCM) of uncommon electron transfer from oxygen to copper ions is unraveled in a novel P2-Na 0.8 Cu 0.22 Li 0.08 Mn 0.67 O 2 cathode for boosting the reversibility and kinetics of anionic redox reactions. The resultant strong covalent Cu–(O–O) bonding can efficaciously suppress excessive oxygen oxidation and irreversible cation migration. Consequently, the P2-Na 0.8 Cu 0.22 Li 0.08 Mn 0.67 O 2 cathode delivers a marvelous rate capability (134.1 and 63.2 mAh g –1 at 0.1C and 100C, respectively) and outstanding long-term cycling stability (82% capacity retention after 500 cycles at 10C). The intrinsic functioning mechanisms of RCM are fully understood through systematic in situ/ex situ characterizations and theoretical…

Sodium-ion batteries have garnered unprecedented attention as an electrochemical energy storage technology, but it remains challenging to design high-energy-density cathode materials with low structural strain during the dynamic (de)sodiation processes. Herein, we report a P2-layered lithium dual-site-substituted Na 0.7 Li 0.03 [Mg 0.15 Li 0.07 Mn 0.75 ]O 2 (NMLMO) cathode material, in which Li ions occupy both transition-metal (TM) and alkali-metal (AM) sites. The combination of theoretical calculations and experimental characterizations reveals that Li TM creates Na–O–Li electronic configurations to boost the capacity derived from the oxygen anionic redox, while Li AM serves as LiO 6 prismatic pillars to stabilize the layered structure through suppressing the detrimental phase transitions. As a result, NMLMO delivers a high specific capacity of 266 mAh g –1 and simultaneously exhibits the nearly zero-strain characteristic within a wide voltage range of 1.5–4.6 V. Our findings highlight the effective way of dual-site substitution to break the capacity–stability trade-off in cathode…

Copper (Cu), a promising catalyst for electrochemical CO 2 reduction (CO 2 R) to multi-electron reduction products, suffers from an unavoidable and uncontrollable reconstruction process during the reaction, which not only may lead to catalyst deactivation but also brings great challenges to the exploration of the structure–performance relationship. Herein, we present an efficient strategy for stabilizing Cu with silica and synthesize reconstruction-resistant CuSiO x amorphous nanotube catalysts with abundant atomic Cu–O–Si interfacial sites. The strong interfacial interaction between Cu and silica makes the Cu–O–Si interfacial sites ultrastable in the CO 2 R reaction without any apparent reconstruction, thus exhibiting high CO 2 -to-CH 4 selectivity (72.5%) and stability (FE CH 4 remains above 60% after 12 h of test). A remarkable CO 2 -to-CH 4 conversion rate of 0.22 μmol cm –2 s –1 was also achieved in a flow cell device. This work provides a very promising route for the design of highly active and stable Cu-based CO 2 R catalysts.

Type I photosensitization provides an effective solution to the problem of unsatisfactory photodynamic therapeutic (PDT) effects caused by the tumor hypoxia. The challenge in the development of Type I mode is to boost the photosensitizer’s own electron transfer capacity. Herein, we found that the use of bovine serum albumin ( BSA ) to encapsulate a thermally activated delayed fluorescence (TADF) photosensitizer PS can significantly promote the Type I PDT process to generate a mass of superoxide anions (O 2 •– ). This Type I photosensitization opened a new strategy by employing BSA as “electron reservoir” and TADF photosensitizer as “electron pump”. We integrated these roles of BSA and PS in one system by preparing nanophotosensitizer PS@BSA . The Type I PDT performance was demonstrated with tumor cells under hypoxic conditions. Furthermore, PS@BSA took full advantage of the tumor-targeting role of BSA and achieved efficient PDT for tumor-bearing mice in the in vivo experiments. This work provides an effective route to improve the PDT efficiency of hypoxic tumors.

Hole-collecting monolayers have drawn attention in perovskite solar cell research due to their ease of processing, high performance, and good durability. Since molecules in the hole-collecting monolayer are typically composed of functionalized π-conjugated structures, hole extraction is expected to be more efficient when the π-cores are oriented face-on with respect to the adjacent surfaces. However, strategies for reliably controlling the molecular orientation in monolayers remain elusive. In this work, multiple phosphonic acid anchoring groups were used to control the molecular orientation of a series of triazatruxene derivatives chemisorbed on a transparent conducting oxide electrode surface. Using infrared reflection absorption spectroscopy and metastable atom electron spectroscopy, we found that multipodal derivatives align face-on to the electrode surface, while the monopodal counterpart adopts a more tilted configuration. The face-on orientation was found to facilitate hole extraction, leading to inverted perovskite solar cells with enhanced stability and high-power…

In this work, we have fabricated an aryl amino-substituted graphitic carbon nitride (g-C 3 N 4 ) catalyst with atomically dispersed Mn capable of generating hydrogen peroxide (H 2 O 2 ) directly from seawater. This new catalyst exhibited excellent reactivity, obtaining up to 2230 μM H 2 O 2 in 7 h from alkaline water and up to 1800 μM from seawater under identical conditions. More importantly, the catalyst was quickly recovered for subsequent reuse without appreciable loss in performance. Interestingly, unlike the usual two-electron oxygen reduction reaction pathway, the generation of H 2 O 2 was through a less common two-electron water oxidation reaction (WOR) process in which both the direct and indirect WOR processes occurred; namely, photoinduced h + directly oxidized H 2 O to H 2 O 2 via a one-step 2e – WOR, and photoinduced h + first oxidized a hydroxide (OH – ) ion to generate a hydroxy radical ( • OH), and H 2 O 2 was formed indirectly by the combination of two • OH. We have characterized the material, at the catalytic sites, at the atomic level using electron paramagnetic…

In contrast to the traditional and widely-used cycloaddition reactions involving at least a π bond component, a [2σ + 2σ] radical cycloaddition between bicyclo[1.1.0]butanes (BCBs) and cyclopropyl ketones has been developed to provide a modular, concise, and atom-economical synthetic route to substituted bicyclo[3.1.1]heptane (BCH) derivatives that are 3D bioisosteres of benzenes and core skeleton of a number of terpene natural products. The reaction was catalyzed by a combination of simple tetraalkoxydiboron(4) compound B 2 pin 2 and 3-pentyl isonicotinate. The broad substrate scope has been demonstrated by synthesizing a series of new highly functionalized BCHs with up to six substituents on the core with up to 99% isolated yield. Computational mechanistic investigations supported a pyridine-assisted boronyl radical catalytic cycle.

Ruthenium(II) polypyridyl complexes form a vast family of molecules characterized by their finely tuned photochemical and photophysical properties. Their ability to undergo excited-state deactivation via photosubstitution reactions makes them quite unique in inorganic photochemistry. As a consequence, they have been used, in general, for building dynamic molecular systems responsive to light but, more particularly, in the field of oncology, as prodrugs for a new cancer treatment modality called photoactivated chemotherapy (PACT). Indeed, the ability of a coordination bond to be selectively broken under visible light irradiation offers fascinating perspectives in oncology: it is possible to make poorly toxic agents in the dark that become activated toward cancer cell killing by simple visible light irradiation of the compound inside a tumor. In this Perspective, we review the most important concepts behind the PACT idea, the relationship between ruthenium compounds used for PACT and those used for a related phototherapeutic approach called photodynamic therapy (PDT), and we discuss…

Catalytic C­(sp3)–H functionalization has provided enormous opportunities to construct organic molecules, facilitating the derivatization of complex pharmaceutical compounds. Within this framework, direct hydrogen atom transfer (HAT) photocatalysis becomes an appealing approach to this goal. However, the viable substrates utilized in these protocols are limited, and the site selectivity shows preference to activated and thermodynamically favored C­(sp3)–H bonds. Herein, we describe the development of undirected iron-catalyzed C­(sp3)–H borylation, thiolation, and sulfinylation reactions enabled by the photoinduced ligand-to-metal charge transfer (LMCT) process. These reactions exhibit remarkably broad substrate scope (>150 examples in total), and most importantly, all of these three reactions show unconventional regioselectivity, with the occurrence of C­(sp3)–H borylation, thiolation, and sulfinylation preferentially at the distal methyl position. The procedures are operationally simple and readily scalable and provide access to high-value products from simple hydrocarbons in one…

Metal–organic frameworks (MOFs) with highly adjustable structures are an emerging family of electrocatalysts in two-electron oxygen reduction reaction (2e-ORR) for H 2 O 2 production. However, the development of MOF-based 2e-ORR catalysts with high H 2 O 2 selectivity and production rate remains challenging. Herein, an elaborate design with fine control over MOFs at both atomic and nano-scale is demonstrated, enabling the well-known Zn/Co bimetallic zeolite imidazole frameworks (ZnCo-ZIFs) as excellent 2e-ORR electrocatalysts. Experimental results combined with density functional theory simulation have shown that the atomic level control can regulate the role of water molecules participating in the ORR process, and the morphology control over desired facet exposure adjusts the coordination unsaturation degree of active sites. The structural regulation at two length scales leads to synchronous control over both the kinetics and thermodynamics for ORR on bimetallic ZIF catalysts. The optimized ZnCo-ZIF with a Zn/Co molar ratio of 9/1 and predominant {001} facet exposure exhibits a…

Lithium–sulfur (Li–S) batteries suffer from sluggish kinetics due to the poor conductivity of sulfur cathodes and polysulfide shutting. Current studies on sulfur redox catalysis mainly focus on the adsorption and catalytic conversion of lithium polysulfides but ignore the modulation of the electronic structure of the catalysts which involves spin-related charge transfer and orbital interactions. In this work, bimetallic phosphorus trisulfides embedded in Prussian blue analogue-derived nitrogen-doped hollow carbon nanocubes (FeCoPS 3 /NCs) were elaborately synthesized as a host to reveal the relationship between the catalytic activity and the spin state configuration for Li–S batteries. Orbital spin splitting in FeCoPS 3 drives the electronic structure transition from low-spin to high-spin states, generating more unpaired electrons on the 3d orbit. Specifically, the nondegenerate orbitals involved in the high-spin configuration of FeCoPS 3 result in the upshift of energy levels, generating more active electronic states. Such tailored electronic structure increases the charge…

Lithium (Li) metal batteries (LMBs) are regarded as one of the most promising energy storage systems due to their ultrahigh theoretical energy density. However, the high reactivity of the Li anodes leads to the decomposition of the electrolytes, presenting a huge impediment to the practical application of LMBs. The routine trial-and-error methods are inefficient in designing highly stable solvent molecules for the Li metal anode. Herein, a data-driven approach is proposed to probe the origin of the reductive stability of solvents and accelerate the molecular design for advanced electrolytes. A large database of potential solvent molecules is first constructed using a graph theory-based algorithm and then comprehensively investigated by both first-principles calculations and machine learning (ML) methods. The reductive stability of 99% of the electrolytes decreases under the dominance of ion-solvent complexes, according to the analysis of the lowest unoccupied molecular orbital (LUMO). The LUMO energy level is related to the binding energy, bond length, and orbital ratio factors. An…

The electroreduction of CO 2 into value-added liquid fuels holds great promise for addressing global environmental and energy challenges. However, achieving highly selective yielding of multi-carbon oxygenates through the electrochemical CO 2 reduction reaction (eCO 2 RR) is a formidable task, primarily due to the sluggish asymmetric C–C coupling reaction. In this study, a novel metal–organic framework ( CuSn–HAB ) with unprecedented heterometallic Sn···Cu dual sites (namely, a pair of SnN 2 O 2 and CuN 4 sites bridged by μ -N atoms) was designed to overcome this limitation. CuSn–HAB demonstrated an impressive Faradic efficiency (FE) of 56(2)% for eCO 2 RR to alcohols, achieving a current density of 68 mA cm –2 at a low potential of −0.57 V (vs RHE). Notably, no significant degradation was observed over a continuous 35 h operation at the specified current density. Mechanistic investigations revealed that, in comparison to the copper site, the SnN 2 O 2 site exhibits a higher affinity for oxygen atoms. This enhanced affinity plays a pivotal role in facilitating the generation of the…

Oral squamous cell carcinoma (OSCC) is the most common oral cancer, having high recurrence and metastasis features. In addition to surgery, photodynamic therapy (PDT) is considered as another effective approach for OSCC treatment. The water solubility of currently available PDT photosensitizers (PSs) is poor, lowering their singlet oxygen ( 1 O 2 ) yield and consequent PDT efficiency. Strategies of PS assembly have been reported to increase 1 O 2 yield, but it is still possible to further enhance PDT efficiency. In this work, we utilized apoptosis to amplify the assembly of porphyrin nanofibers for enhanced PDT of OSCC. A water-soluble porphyrin derivative, Ac-Asp-Glu-Val-Asp-Asp-TPP (Ac-DEVDD-TPP), was designed for this purpose. Upon caspase-3 (Casp3, an activated enzyme during apoptosis) cleavage and laser irradiation, Ac-DEVDD-TPP was converted to D-TPP, which spontaneously self-assembled into porphyrin nanofibers, accompanied by 1.4-fold and 2.1-fold 1 O 2 generations in vitro and in cells, respectively. The as-formed porphyrin nanofiber induced efficient cell apoptosis and…

Nations, industries, and aspects of everyday life have undergone forgery and counterfeiting ever since the emergence of commercialization. Securing documents and products with anticounterfeit additives shows promise for authentication, allowing one to combat ever-increasing global counterfeiting. One most-used effective encryption strategy is to combine with optical-security markers on the required protection objects; however, state-of-the-art labels still suffer from imitation due to their poor complexity and easy forecasting, as a result of deterministic production. Developing advanced anticounterfeiting tags with unusual optical characters and further incorporating complex security features are desired to achieve multimodal, unbreakable authentication capacity; unfortunately, this has not yet been achieved. Here, we prepare a series of stable circularly polarized luminescence (CPL) materials, composed of toxicity-free, high-quality-emitting inorganic quantum dots (QDs) and liquid crystals, using a designed helical-coassembly strategy. This CPL system achieves a figure of merit…

Covalent organic frameworks (COFs) are usually synthesized under solvothermal conditions that require the use of toxic organic solvents, high reaction temperatures, and complicated procedures. Additionally, their insolubility and infusibility present substantial challenges in the processing of COFs. Herein, we report a facile, green approach for the synthesis of imine-linked COFs in an aqueous solution at room temperature. The key behind the synthesis is the regulation of the reaction rate. The preactivation of aldehyde monomers using acetic acid significantly enhances their reactivity in aqueous solutions. Meanwhile, the still somewhat lower imine formation rate and higher imine breaking rates in aqueous solution, in contrast to conventional solvothermal synthesis, allow for the modulation of the reaction equilibrium and the crystallization of the products. As a result, highly crystalline COFs with large surface areas can be formed in relatively high yields in a few minutes. In total, 16 COFs are successfully synthesized from monomers with different molecular sizes, geometries,…

Covalent organic framework (COF) chemistry is experiencing unprecedented development in recent decades. The current studies on COF chemistry are mainly focused on the discovery of novel covalent linkages, new topological structures, synthetic methodologies, and potential applications. However, despite the fact that noncovalent interactions are ubiquitous in COF chemistry, relatively little attention has been given to the role of noncovalent bonds on COF structures and their properties. In this work, a series of hydrazone-linked COFs involving noncovalent hydrogen bonds have been constructed, where the hydrogen-bonding interaction plays critical roles in the COF crystallinity and structures. The regulation of structural flexibility, the reversible transition between order and disorder, and the variety of host-guest interactions have been demonstrated in succession for the first time in COFs. The results obtained by the hydrogen-bonding-regulated strategy may also be extendable to other noncovalent interactions, such as π-π interactions, metal coordination interactions, Lewis…

Redox-active covalent organic frameworks (COFs) have recently emerged as advanced electrodes in polymer batteries. COFs provide ideal molecular precision for understanding redox mechanisms and increasing the theoretical charge-storage capacities. Furthermore, the functional groups on the pore surface of COFs provide highly ordered and easily accessible interaction sites, which can be modeled to establish a synergy between ex situ/in situ mechanism studies and computational methods, permitting the creation of predesigned structure-property relationships. This perspective integrates and categorizes the redox functionalities of COFs, providing a deeper understanding of the mechanistic investigation of guest ion interactions in batteries. Additionally, it highlights the tunable electronic and structural properties that influence the activation of redox reactions in this promising organic electrode material.

Abstract Dearomative photocycloadditions are valuable chemical transformations, serving as an efficient platform to create three-dimensional molecular complexity. However, the photolability of the original addition product especially within the context of ortho cycloadditions often causes undesired consecutive rearrangements, rendering these ortho cycloadducts elusive. Herein, we report an ortho-selective intermolecular photocycloaddition of bicyclic aza-arenes including (iso)quinolines, quinazolines, and quinoxalines by utilizing a strain-release approach. With bicyclo[1.1.0]butanes as coupling partners, this dearomative [2π + 2σ] cycloaddition enables the straightforward construction of C(sp3)-rich bicyclo[2.1.1]hexanes directly connected to N-heteroarenes. Photophysical experiments and DFT calculations revealed the origin of the [2π + 2σ] selectivity and indicate that, in addition to the originally proposed energy transfer or direct excitation pathways, a chain reaction mechanism is operative depending on the reaction conditions.

Ammonia borane (AB) has been regarded as a promising material for chemical hydrogen storage. However, the development of efficient, cost-effective, and stable catalysts for H 2 generation from AB hydrolysis remains a bottleneck for realizing its practical application. Herein, a step-by-step reduction strategy has been developed to synthesize a series of bimetallic species with small sizes and high dispersions onto various metal oxide supports. Superior to other non-noble metal species, the introduction of Co species can remarkably and universally promote the catalytic activity of various noble metals (e.g., Pt, Rh, Ru, and Pd) in AB hydrolysis reactions. The optimized Pt 0.1% Co 3% /TiO 2 catalyst exhibits a superhigh H 2 generation rate from AB hydrolysis, showing a turnover frequency (TOF) value of 2250 mol H 2 mol Pt –1 min –1 at 298 K. Such a TOF value is about 10 and 15 times higher than that of the monometal Pt/TiO 2 and commercial Pt/C catalysts, respectively. The density functional theory (DFT) calculation reveals that the synergy between Pt and CoO species can remarkably…

The low salt adsorption capacities (SACs) of benchmark carbon materials (usually below 20 mg g –1 ) are one of the most challenging issues limiting further commercial development of capacitive deionization (CDI), an energetically favorable method for sustainable water desalination. Sodium superionic conductor (NASICON)-structured NaTi 2 (PO 4 ) 3 (NTP) materials, especially used in combination with carbon to prepare NTP/C materials, provide emerging options for higher CDI performance but face the problems of poor cycling stability and dissolution of active materials. In this study, we report the development of the yolk–shell nanoarchitecture of NASICON-structured NTP/C materials (denoted as ys -NTP@C) using a metal–organic framework@covalent organic polymer (MOF@COP) as a sacrificial template and space-confined nanoreactor. As expected, ys -NTP@C exhibits good CDI performance, including exemplary SACs with a maximum SAC of 124.72 mg g –1 at 1.8 V in the constant-voltage mode and 202.76 mg g –1 at 100 mA g –1 in the constant-current mode, and good cycling stability without obvious…

compounds, for which long-lived MLCT states have become accessible over the past five years. Furthermore, we discuss possible future developments in the search for new first-row transition metal complexes with partially filled 3d subshells and photoactive MLCT states for next-generation applications in photophysics and photochemistry.

Sn-based materials have been demonstrated as promising catalysts for the selective electrochemical CO 2 reduction reaction (CO 2 RR). However, the detailed structures of catalytic intermediates and the key surface species remain to be identified. In this work, a series of single-Sn-atom catalysts with well-defined structures is developed as model systems to explore their electrochemical reactivity toward CO 2 RR. The selectivity and activity of CO 2 reduction to formic acid on Sn-single-atom sites are shown to be correlated with Sn(IV)-N 4 moieties axially coordinated with oxygen (O–Sn–N 4 ), reaching an optimal HCOOH Faradaic efficiency of 89.4% with a partial current density ( j HCOOH ) of 74.8 mA·cm –2 at −1.0 V vs reversible hydrogen electrode (RHE). Employing a combination of operando X-ray absorption spectroscopy, attenuated total reflectance surface-enhanced infrared absorption spectroscopy, Raman spectroscopy, and 119 Sn Mössbauer spectroscopy, surface-bound bidentate tin carbonate species are captured during CO 2 RR. Moreover, the electronic and coordination structures of…

The multi-redox mechanism involving multi-sites has great implications to dictate the catalytic water oxidation. Understanding the sequential dynamics of multi-steps in oxygen evolution reaction (OER) cycles on working catalysts is a highly important but challenging issue. Here, using quasi-operando transient absorption (TA) spectroscopy and a typical photosensitization strategy, we succeeded in resolving the sequential oxidation kinetics involving multi-active sites for water oxidation in OER catalytic cycle, with Co 3 O 4 nanoparticles as model catalysts. When OER initiates from fast oxidation of surface Co 2+ ions, both surface Co 2+ and Co 3+ ions are active sites of the multi-cobalt centers for water oxidation. In the sequential kinetics (Co 2+ → Co 3+ → Co 4+ ), the key characteristic is fast oxidation and slow consumption for all the cobalt species. Due to this characteristic, the Co 4+ intermediate distribution plays a determining role in OER activity and results in the slow overall OER kinetics. These insights shed light on the kinetic understanding of water oxidation on…

Immunotherapy is currently the most promising treatment strategy for long-term tumor regression. However, current cancer immunotherapy shows low response rates due to insufficient immunogenicity of tumor cells. Herein, we report a strategy to keep tumor cells highly immunogenic by triggering cascade immunogenic tumor ferroptosis. We developed a six-enzyme co-expressed nanoplatform: lipoxygenase (LOX) and phospholipase A2 (PLA2)-co-loaded FeCo/Fe–Co dual-metal atom nanozyme (FeCo/Fe–Co DAzyme/PL), which can not only induce initial immunogenic tumor ferroptosis through its own multi-enzyme mimetic activities but also up-regulate arachidonic acid (AA) expression to synergize with CD8 + T cell-derived IFN-γ to induce ACSL4-mediated immunogenic tumor ferroptosis. During this process, FeCo/Fe–Co DAzyme/PL can induce lipid peroxidation (LPO) by efficiently generating reactive oxygen species (ROS) and depleting GSH and GPX4 at tumor sites. Additionally, free AA released from PLA2 catalysis is converted into arachidonyl-CoA under the activation of ACSL4 stimulated by IFN-γ, which is further…

Multicomponent reactions (MCRs) combine at least three reactants to afford the desired product in a highly atom-economic way and are therefore viewed as efficient one-pot combinatorial synthesis tools allowing one to significantly boost molecular complexity and diversity. Nowadays, MCRs are no longer confined to organic synthesis and have found applications in materials chemistry. In particular, MCRs can be used to prepare covalent organic frameworks (COFs), which are crystalline porous materials assembled from organic monomers and exhibit a broad range of properties and applications. This synthetic approach retains the advantages of small-molecule MCRs, not only strengthening the skeletal robustness of COFs, but also providing additional driving forces for their crystallization, and has been used to prepare a series of robust COFs with diverse applications. The present perspective article provides the general background for MCRs, discusses the types of MCRs employed for COF synthesis to date, and addresses the related critical challenges and future perspectives to inspire the…

High Resolution Image Download MS PowerPoint Slide Electrocatalytic reduction of carbon dioxide into value-added chemical fuels is a promising way to achieve carbon neutrality. Bismuth-based materials have been considered as favorable electrocatalysts for converting carbon dioxide to formic acid. Moreover, size-dependent catalysis offers significant advantages in catalyzed heterogeneous chemical processes. However, the size effects of bismuth nanoparticles on formic acid production have not been fully explored. Here, we prepared Bi nanoparticles uniformly supported on porous TiO 2 substrate electrocatalytic materials by in situ segregation of the Bi element from Bi 4 Ti 3 O 12 . The Bi-TiO 2 electrocatalyst with Bi nanoparticles of 2.83 nm displays a Faradaic efficiency of greater than 90% over a wide potential range of 400 mV. Theoretical calculations have also demonstrated subtle electronic structural evolutions induced by the size variations of Bi nanoparticles, where the 2.83 nm Bi nanoparticles display the most active p-band and d-band centers to guarantee high electroactivity…

Charge compensation from cationic and anionic redox couples accompanying Na + (de)intercalation in layered oxide cathodes contributes to high specific capacity. However, the engagement level of different redox couples remains unclear and their relationship with Na + content is less studied. Here we discover that it is possible to take full advantage of the high-voltage transition metal (TM) redox reaction through low-valence cation substitution to tailor the electronic structure, which involves an increased ratio of Na + content to available charge transfer number of TMs. Taking Na x Cu 0.11 Ni 0.11 Fe 0.3 Mn 0.48 O 2 as the example, the Li + substitution increases the ratio to facilitate the high-voltage TM redox activity, and further F-ion substitution decreases the covalency of the TM–O bond to relieve structural changes. As a consequence, the final high-entropy Na 0.95 Li 0.07 Cu 0.11 Ni 0.11 Fe 0.3 Mn 0.41 O 1.97 F 0.03 cathode demonstrates ∼29% capacity increase contributed by the high-voltage TMs and exhibits excellent long-term cycling stability due to the improved…

Metal-isolated clusters (MICs) physically confined on photoactive materials are of great interest in the field of photosynthesis of hydrogen peroxide (H 2 O 2 ). Despite recent important endeavors, weak confinement of MICs in the reported photocatalytic systems leads to their low catalytic activity and stability. Herein, we report a new strategy of fluorinated covalent organic frameworks (COFs) to strongly confine Pd ICs for greatly boosting the photocatalytic activity and stability of H 2 O 2 photosynthesis. Both experimental and theoretical results reveal that strong electronegative fluorine can increase the metal–support interaction and optimize the d-band center of Pd ICs, thus significantly enhancing the stability and activity of photocatalytic H 2 O 2 . An optimal TAPT-TFPA COFs@Pd ICs photocatalyst delivers a stable H 2 O 2 yield rate of 2143 μmol h –1 g –1 . Most importantly, the as-made TAPT-TFPA COFs@Pd ICs exhibit high catalytic stability over 100 h, which is the best among the reported materials.

Lithium metal batteries (LMBs) coupled with a high-voltage Ni-rich cathode are promising for meeting the increasing demand for high energy density. However, aggressive electrode chemistry imposes ultimate requirements on the electrolytes used. Among the various optimized electrolytes investigated, localized high-concentration electrolytes (LHCEs) have excellent reversibility against a lithium metal anode. However, because they consist of thermally and electrochemically unstable solvents, they have inferior stability at elevated temperatures and high cutoff voltages. Here we report a semisolvated sole-solvent electrolyte to construct a typical LHCE solvation structure but with significantly improved stability using one bifunctional solvent. The designed electrolyte exhibits exceptional stability against both electrodes with suppressed lithium dendrite growth, phase transition, microcracking, and transition metal dissolution. A Li||Ni 0.8 Co 0.1 Mn 0.1 O 2 cell with this electrolyte operates stably over a wide temperature range from −20 to 60 °C and has a high capacity retention of…

Zn dendrite growth and undesired parasitic reactions severely restrict the practical use of deep-cycling Zn metal anodes (ZMAs). Herein, we demonstrate an elaborate design of atomically dispersed Cu and Zn sites anchored on N,P-codoped carbon macroporous fibers (denoted as Cu/Zn-N/P-CMFs) as a three-dimensional (3D) versatile host for efficient ZMAs in mildly acidic electrolyte. The 3D macroporous frameworks can alleviate the structural stress and suppress Zn dendrite growth by spatially homogenizing Zn 2+ flux. Moreover, the well-dispersed Cu and Zn atoms anchored by N and P atoms maximize the utilization as abundant active nucleation sites for Zn plating. As expected, the Cu/Zn-N/P-CMFs host presents a low Zn nucleation overpotential, high reversibility, and dendrite-free Zn deposition. The Cu/Zn-N/P-CMFs-Zn electrode exhibits stable Zn plating/stripping with low polarization for 630 h at 2 mA cm –2 and 2 mAh cm –2 . When coupled with a MnO 2 cathode, the fabricated full cell also shows impressive cycling performance even when tested under harsh conditions.

Rational regulation of the reaction pathway to produce the desired products is one of the most significant challenges in the electrochemical CO 2 reduction reaction (CO 2 RR). Herein, we designed a series of rare-earth Cu catalysts with mixed phases. It was found that the products could be switched from C 2+ to CH 4 by tuning the composition and structure of the catalysts. Particularly at the Cu/Sm atomic ratio of 9/1 (Cu 9 Sm 1 –O x ), the Faradaic efficiency (FE) for C 2+ products (FE C 2+ ) could reach 81% at 700 mA cm –2 with negligible CH 4 . However, the FE of CH 4 (FE CH 4 ) was 65% at 500 mA cm –2 over Cu 1 Sm 9 –O x (Cu/Sm = 1/9), and the FE C 2+ was extremely low. Experiments and theoretical studies indicated that the stable CuSm 2 O 4 phase existed in all the catalysts within the Cu/Sm range of 9/1 to 1/9. At a high Cu content, the catalyst was composed of CuSm 2 O 4 and Cu phases. The small amount of Sm could enhance the binding strength of *CO and facilitate C–C coupling. Conversely, at a high Sm content, the catalyst was composed of CuSm 2 O 4 and Sm 2 O 3 phases. Sm…

A highly active and stable Cu-based catalyst for CO 2 to CO conversion was demonstrated by creating a strong metal–support interaction (SMSI) between Cu active sites and the TiO 2 -coated dendritic fibrous nano-silica (DFNS/TiO 2 ) support. The DFNS/TiO 2 –Cu10 catalyst showed excellent catalytic performance with a CO productivity of 5350 mmol g –1 h –1 (i.e., 53,506 mmol g Cu –1 h –1 ), surpassing that of almost all copper-based thermal catalysts, with 99.8% selectivity toward CO. Even after 200 h of reaction, the catalyst remained active. Moderate initial agglomeration and high dispersion of nanoparticles (NPs) due to SMSI made the catalysts stable. Electron energy loss spectroscopy confirmed the strong interactions between copper NPs and the TiO 2 surface, supported by in situ diffuse reflectance infrared Fourier transform spectroscopy and X-ray photoelectron spectroscopy. The H 2 -temperature programmed reduction (TPR) study showed α, β, and γ H 2 -TPR signals, further confirming the presence of SMSI between Cu and TiO 2 . In situ Raman and UV–vis diffuse reflectance…

The copper-based (Cu-based) electrocatalytic materials effectively carry out the electrocatalytic carbon dioxide reduction reaction (CO 2 RR) toward C 2+ products, yet the superiority and stability of the oxidation state of Cu are still worth studying. Herein, we designed and prepared three Cu-based electrocatalysts with different oxidation states to study the valence state–activity relationship. Among these Cu-based electrocatalysts, the Cu 2 O nanosheets with thickness of only 0.9 nm show an extremely high C 2+ Faraday efficiency (FE C 2+ ) of ∼81%, and the FE C 2+ has an increase of 37% compared with the traditional CuO x phase. The ultrathin two-dimensional (2D) nanosheet structure with abundant oxygen vacancies can stabilize the oxidation state of Cu to improve the selectivity for C 2+ products in CO 2 RR. In situ Raman spectroscopy and density functional theory calculations demonstrate that the rich Cu + in the ultrathin 2D Cu 2 O nanosheets is the most suitable oxidation state for *CO adsorption and coverage on the catalyst surface, which promotes the C–C coupling reaction in…

Electrocatalytic carbon dioxide reduction (CO 2 R) in neutral electrolytes can mitigate the energy and carbon losses caused by carbonate formation but often experiences unsatisfied multicarbon selectivity and reaction rates because of the kinetic limitation to the critical carbon monoxide (CO)–CO coupling step. Here, we describe that a dual-phase copper-based catalyst with abundant Cu(I) sites at the amorphous–nanocrystalline interfaces, which is electrochemically robust in reducing environments, can enhance chloride-specific adsorption and consequently mediate local *CO coverage for improved CO–CO coupling kinetics. Using this catalyst design strategy, we demonstrate efficient multicarbon production from CO 2 R in a neutral potassium chloride electrolyte (pH ∼6.6) with a high Faradaic efficiency of 81% and a partial current density of 322 milliamperes per square centimeter. This catalyst is stable after 45 h of operation at current densities relevant to commercial CO 2 electrolysis (300 mA per square centimeter).

Recycling spent lithium-ion batteries (LIBs) has become an urgent task to address the issues of resource shortage and potential environmental pollution. However, direct recycling of the spent LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523) cathode is challenging because the strong electrostatic repulsion from a transition metal octahedron in the lithium layer provided by the rock salt/spinel phase that is formed on the surface of the cycled cathode severely disrupts Li + transport, which restrains lithium replenishment during regeneration, resulting in the regenerated cathode with inferior capacity and cycling performance. Here, we propose the topotactic transformation of the stable rock salt/spinel phase into Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 and then back to the NCM523 cathode. As a result, a topotactic relithiation reaction with low migration barriers occurs with facile Li + transport in a channel (from one octahedral site to another, passing through a tetrahedral intermediate) with weakened electrostatic repulsion, which greatly improves lithium replenishment during regeneration. In addition, the…

Covalent organic framework (COF) materials with porous character and robust structure have significant applied implications for K-ion battery (KIB) anodes, but they are limited by the low reversible capacity and inferior rate capability. Here, based on theoretical calculations, we identified that a porous bulk COF featuring numerous pyrazines and carbonyls in the π-conjugated periodic skeleton could provide multiple accessible redox-active sites for high-performance potassium storage. Its porous structure with a surface-dominated storage mechanism enabled the fast and stable storage of K-ions. Its insolubility in organic electrolytes and small volumetric change after potassiation ensured a robust electrode for stable cycling. As a KIB anode, this bulk COF demonstrated an unprecedentedly outstanding combination of reversible capacity (423 mAh g –1 at 0.1 C), rate capability (185 mAh g –1 at 10 C), and cyclability. The theoretical simulation and comprehensive characterizations confirmed the active sites are contributed by C═O, C═N, and the cation−π effect.

Functional additives that can interact with the perovskite precursors to form the intermediate phase have been proven essential in obtaining uniform and stable α-FAPbI 3 films. Among them, Cl-based volatile additives are the most prevalent in the literature. However, their exact role is still unclear, especially in inverted perovskite solar cells (PSCs). In this work, we have systematically studied the functions of Cl-based volatile additives and MA-based additives in formamidinium lead iodide (FAPbI 3 )-based inverted PSCs. Using in situ photoluminescence, we provide clear evidence to unravel the different roles of volatile additives (NH 4 Cl, FACl, and MACl) and MA-based additives (MACl, MABr, and MAI) in the nucleation, crystallization, and phase transition of FAPbI 3 . Three different kinds of crystallization routes are proposed based on the above additives. The non-MA volatile additives (NH 4 Cl and FACl) were found to promote crystallization and lower the phase-transition temperatures. The MA-based additives could quickly induce MA-rich nuclei to form pure α-phase FAPbI 3 and…

The limitations of conventional strategies in finely controlling the composition and structure demand new promotional effects for upgrading the reverse water–gas shift (RWGS) catalysts for enhanced fuel production. We report the design and synthesis of a hetero-dual-site catalyst for boosting RWGS performance by controllably loading Fe atoms at the neighboring Pt atom on the surface of commercial CeO 2 . The Fe–Pt/CeO 2 exhibits a remarkably high catalytic performance (TOF Pt: 43,519 h –1 ) for CO 2 to CO conversion with ∼100% CO selectivity at a relatively low temperature of 350 °C. Furthermore, the catalyst retains over 80% activity after 200 h of continuous operation. The experimental and computational investigations reveal a “two-way synergistic effect”, where Fe atoms can not only serve as promotors to alter the charge density of Pt atoms but also be activated by the excess active hydrogen species generated by Pt atoms, enhancing catalytic activity and stability.

High Resolution Image Download MS PowerPoint Slide Controlling multimetallic ensembles at the atomic level is significantly challenging, particularly for high-entropy alloys with more than five elements. Herein, we report an innovative ultrasmall (∼2 nm) PtFeCoNiCuZn high-entropy intermetallic (PFCNCZ-HEI) with a well-ordered structure synthesized by using the space-confined strategy. By exploiting these combined metals, the PFCNCZ-HEI nanoparticles achieve an ultrahigh mass activity of 2.403 A mg Pt –1 at 0.90 V vs reversible hydrogen electrode for the oxygen reduction reaction, which is up to 19-fold higher than that of state-of-the-art commercial Pt/C. A proton exchange membrane fuel cell assembled with PFCNCZ-HEI as the cathode (0.03 mg Pt cm –2 ) exhibits a power density of 1.4 W cm –2 and a high mass-normalized rated power of 45 W mg Pt –1 . Furthermore, theoretical calculations reveal that the outer electrons of the non-noble-metal atoms on the surface of the PFCNCZ-HEI nanoparticle are modulated to show characteristics of multiple active centers. This work offers a promising…

We report the use of photocatalysis for the homolytic ring-opening of carbonyl cyclopropanes. In contrast to previous studies, our approach does not require a metal cocatalyst or a strong reductant. The carbonyl cyclopropanes can be employed for both [2σ + 2σ] and [2σ + 2π] annulation with either alkenes/alkynes or bicyclo[1.1.0]butanes, yielding cyclopent-anes/-enes and bicyclo[3.1.1]heptanes (BCHs), respectively. BCHs are promising bioisosteres for 1,2,4,5 tetra-substituted aromatic rings. Mechanistic studies, including density functional theory computation and a trapping experiment with DMPO, support a 1,3-biradical generated from cyclopropane as a key intermediate for these transformations.

Realizing efficient hydrogenation of N 2 molecules in the electrocatalytic nitrogen reduction reaction (NRR) is crucial in achieving high activity at a low potential because it theoretically requires a higher equilibrium potential than other steps. Analogous to metal hydride complexes for N 2 reduction, achieving this step by chemical hydrogenation can weaken the potential dependence of the initial hydrogenation process. However, this strategy is rarely reported in the electrocatalytic NRR, and the catalytic mechanism remains ambiguous and lacks experimental evidence. Here, we show a highly efficient electrocatalyst (ruthenium single atoms anchored on graphdiyne/graphene sandwich structures) with a hydrogen radical-transferring mechanism, in which graphdiyne (GDY) generates hydrogen radicals (H • ), which can effectively activate N 2 to generate NNH radicals ( • NNH). A dual-active site is constructed to suppress competing hydrogen evolution, where hydrogen preferentially adsorbs on GDY and Ru single atoms serve as the adsorption site of • NNH to promote further hydrogenation of NH…

Electrocatalytic nitric oxide (NO) reduction not only provides an extremely promising strategy for ambient NH 3 generation but also alleviates the artificially disrupted N-cycle balance. However, exploring efficient electrocatalysts to enhance the NO electroreduction performance remains a significant challenge. Herein, a hexagonal-close-packed Co nanosheet (hcp-Co) is prepared and exhibits a high NH 3 yield of 439.50 μmol cm –2 h –1 and a Faraday efficiency of 72.58%, outperforming the face-centered cubic phase of the Co nanosheet (fcc-Co) and most reported electrocatalysts. Through the combination of density functional theory calculations and NO temperature-programmed desorption experiments, the superior catalytic NO reduction reaction (NORR) activity on the hcp-Co can be attributed to the unique electron structures and proton shuttle effect. A proof-of-concept device of Zn–NO batteries using the hcp-Co as the cathode is assembled and shows a power density of 4.66 mW cm –2, which is superior to the reported performance in the literature so far.