The 100 most-cited articles in Journal of the American Chemical Society, 2022

Anode-free metal batteries can in principle offer higher energy density, but this requires them to have extraordinary Coulombic efficiency (>99.7%). Although Zn-based metal batteries are promising for stationary storage, the parasitic side reactions make anode-free batteries difficult to achieve in practice. In this work, a salting-in-effect-induced hybrid electrolyte is proposed as an effective strategy that enables both a highly reversible Zn anode and good stability and compatibility toward various cathodes. The as-prepared electrolyte can also work well under a wide temperature range (i.e., from −20 to 50 °C). It is demonstrated that in the presence of propylene carbonate, triflate anions are involved in the Zn 2+ solvation sheath structure, even at a low salt concentration (2.14 M). The unique solvation structure results in the reduction of anions, thus forming a hydrophobic solid electrolyte interphase. The waterproof interphase along with the decreased water activity in the hybrid electrolyte effectively prevents side reactions, thus ensuring a stable Zn anode with an…

Single-atom-site catalysts (SASCs) featuring maximized atom utilization and isolated active sites have progressed tremendously in recent years as a highly prosperous branch of catalysis research. Varieties of SASCs have been developed that show excellent performance in many catalytic applications. The major goal of SASC research is to establish feasible synthetic strategies for the preparation of high-performance catalysts, to achieve an in-depth understanding of the active-site structures and catalytic mechanisms, and to develop practical catalysts with industrial value. This Perspective describes the up-to-date development of SASCs and related catalysts, such as dual-atom-site catalysts (DASCs) and nano-single-atom-site catalysts (NSASCs), analyzes the current challenges encountered by these catalysts for industrial applications, and proposes their possible future development path.

Restructuring is ubiquitous in thermocatalysis and of pivotal importance to identify the real active site, yet it is less explored in electrocatalysis. Herein, by using operando X-ray absorption spectroscopy in conjunction with advanced electron microscopy, we reveal the restructuring of the as-synthesized Cu–N 4 single-atom site to the nanoparticles of ∼5 nm during the electrochemical reduction of nitrate to ammonia, a green ammonia production route upon combined with the plasma-assisted oxidation of nitrogen. The reduction of Cu 2+ to Cu + and Cu 0 and the subsequent aggregation of Cu 0 single atoms is found to occur concurrently with the enhancement of the NH 3 production rate, both of them are driven by the applied potential switching from 0.00 to −1.00 V versus RHE. The maximum production rate of ammonia reaches 4.5 mg cm –2 h –1 (12.5 mol NH 3 g Cu –1 h –1 ) with a Faradaic efficiency of 84.7% at −1.00 V versus RHE, outperforming most of the other Cu catalysts reported previously. After electrolysis, the aggregated Cu nanoparticles are reversibly disintegrated into single…

A high-throughput sonochemical synthesis and testing strategy was developed to discover covalent organic frameworks (COFs) for photocatalysis. In total, 76 conjugated polymers were synthesized, including 60 crystalline COFs of which 18 were previously unreported. These COFs were then screened for photocatalytic hydrogen peroxide (H2O2) production using water and oxygen. One of these COFs, sonoCOF-F2, was found to be an excellent photocatalyst for photocatalytic H2O2 production even in the absence of sacrificial donors. However, after long-term photocatalytic tests (96 h), the imine sonoCOF-F2 transformed into an amide-linked COF with reduced crystallinity and loss of electronic conjugation, decreasing the photocatalytic activity. When benzyl alcohol was introduced to form a two-phase catalytic system, the photo-stability of sonoCOF-F2 was greatly enhanced, leading to stable H2O2 production for at least one week.

Hydrogen-bonded organic frameworks (HOFs), self-assembled from strategically pre-designed molecular tectons with complementary hydrogen-bonding patterns, are rapidly evolving into a novel and important class of porous materials. In addition to their common features shared with other functionalized porous materials constructed from modular building blocks, the intrinsically flexible and reversible H-bonding connections endow HOFs with straightforward purification procedures, high crystallinity, solution processability, and recyclability. These unique advantages of HOFs have attracted considerable attention across a broad range of fields, including gas adsorption and separation, catalysis, chemical sensing, and electrical and optical materials. However, the relatively weak H-bonding interactions within HOFs can potentially limit their stability and potential use in further applications. To that end, this Perspective highlights recent advances in the development of chemically and thermally robust HOF materials and systematically discusses relevant design rules and synthesis strategies…

The electrocatalytic C–N coupling for one-step urea synthesis under ambient conditions serves as the promising alternative to the traditional urea synthetic protocol. However, the hydrogenation of intermediate species hinders the efficient urea synthesis. Herein, the oxygen vacancy-enriched CeO 2 was demonstrated as the efficient electrocatalyst with the stabilization of the crucial intermediate of *NO via inserting into vacant sites, which is conducive to the subsequent C–N coupling process rather than protonation, whereas the poor selectivity of C–N coupling with protonation was observed on the vacancy-deficient catalyst. The oxygen vacancy-mediated selective C–N coupling was distinguished and validated by the in situ sum frequency generation spectroscopy. The introduction of oxygen vacancies tailors the common catalyst carrier into an efficient electrocatalyst with a high urea yield rate of 943.6 mg h –1 g –1, superior than that of partial noble-metal-based electrocatalysts. This work provides novel insights into the catalyst design and developments of coupling systems.

High Resolution Image Download MS PowerPoint Slide Electrosynthesis of hydrogen peroxide (H 2 O 2 ) through oxygen reduction reaction (ORR) is an environment-friendly and sustainable route for obtaining a fundamental product in the chemical industry. Co–N 4 single-atom catalysts (SAC) have sparkled attention for being highly active in both 2e – ORR, leading to H 2 O 2 and 4e – ORR, in which H 2 O is the main product. However, there is still a lack of fundamental insights into the structure–function relationship between CoN 4 and the ORR mechanism over this family of catalysts. Here, by combining theoretical simulation and experiments, we unveil that pyrrole-type CoN 4 (Co–N SAC Dp ) is mainly responsible for the 2e – ORR, while pyridine-type CoN 4 catalyzes the 4e – ORR. Indeed, Co–N SAC Dp exhibits a remarkable H 2 O 2 selectivity of 94% and a superb H 2 O 2 yield of 2032 mg for 90 h in a flow cell, outperforming most reported catalysts in acid media. Theoretical analysis and experimental investigations confirm that Co–N SAC Dp ─with weakening O 2 /HOO* interaction─boosts the H 2 O…

Electrochemical glycerol oxidation reaction (GOR) is an attractive alternative anodic reaction to oxygen evolution reaction for a variety of electrolytic synthesis, thanks to the possibility of mass production of glycerol from biomass and the relative low thermodynamic potential of GOR. The development of high-activity cheap electrocatalysts toward GOR yet faces a daunting challenge. Herein, we experimentally prepare a new range of high entropy alloy (HEA) self-supported electrodes with uniform HEA nanoparticles grown on carbon cloth. The systematic electrochemical studies verify that the HEA-CoNiCuMnMo electrode exhibits attractive performance for GOR electrocatalysis with low overpotential and high selectivity toward formate products. The surface atomic configurations of HEA-CoNiCuMnMo are studied by a self-developed machine learning-based Monte Carlo simulation, which points out the catalytic active center to be Mo sites coordinated by Mn, Mo, and Ni. We further develop a hybrid alkali/acid flow electrolytic cell by pairing alkaline GOR with acidic hydrogen evolution reaction…

Solar carbon dioxide (CO 2 ) conversion is an emerging solution to meet the challenges of sustainable energy systems and environmental/climate concerns. However, the construction of isolated active sites not only influences catalytic activity but also limits the understanding of the structure–catalyst relationship of CO 2 reduction. Herein, we develop a universal synthetic protocol to fabricate different single-atom metal sites (e.g., Fe, Co, Ni, Zn, Cu, Mn, and Ru) anchored on the triazine-based covalent organic framework (SAS/Tr-COF) backbone with the bridging structure of metal–nitrogen–chlorine for high-performance catalytic CO 2 reduction. Remarkably, the as-synthesized Fe SAS/Tr-COF as a representative catalyst achieved an impressive CO generation rate as high as 980.3 μmol g –1 h –1 and a selectivity of 96.4%, over approximately 26 times higher than that of the pristine Tr-COF under visible light irradiation. From X-ray absorption fine structure analysis and density functional theory calculations, the superior photocatalytic performance is attributed to the synergic effect of…

The hydrophobic internal cavity and hydrophilic external surface of cyclodextrins (CDs) render promising electrochemical applications. Here, we report a comparative and mechanistic study on the use of CD molecules (α-, β-, and γ-CD) as electrolyte additives for rechargeable Zn batteries. The addition of α-CD in aqueous ZnSO 4 solution reduces nucleation overpotential and activation energy of Zn plating and suppresses H 2 generation. Computational, spectroscopic, and electrochemical studies reveal that α-CD preferentially adsorbs in parallel on the Zn surface via secondary hydroxyl groups, suppressing water-induced side reactions of hydrogen evolution and hydroxide sulfate formation. Additionally, the hydrophilic exterior surface of α-CD with intense electron density simultaneously facilitates Zn 2+ deposition and alleviates Zn dendrite formation. A formulated 3 M ZnSO 4 + 10 mM α-CD electrolyte enables homogenous Zn plating/stripping (average Coulombic efficiency ∼ 99.90%) at 1 mA cm –2 in Zn|Cu cells and a considerable capacity retention of 84.20% after 800 cycles in Zn|V 2 O 5…

Copper is the only metal catalyst that can perform the electrocatalytic CO 2 reduction reaction (CRR) to produce hydrocarbons and oxygenates. Its surface oxidation state determines the reaction pathway to various products. However, under the cathodic potential of CRR conditions, the chemical composition of most Cu-based catalysts inevitably undergoes electroreduction from Cu 2+ to Cu 0 or Cu 1+ species, which is generally coupled with phase reconstruction and the formation of new active sites. Since the initial Cu 2+ active sites are hard to retain, there have been few studies about Cu 2+ catalysts for CRR. Herein we propose a solid-solution strategy to stabilize Cu 2+ ions by incorporating them into a CeO 2 matrix, which works as a self-sacrificing ingredient to protect Cu 2+ active species. In situ spectroscopic characterization and density functional theory calculations reveal that compared with the conventionally derived Cu catalysts with Cu 0 or Cu 1+ active sites, the Cu 2+ species in the solid solution (Cu-Ce-O x ) can significantly strengthen adsorption of the *CO…

Water-alkaline electrolysis holds a great promise for industry-scale hydrogen production but is hindered by the lack of enabling hydrogen evolution reaction electrocatalysts to operate at ampere-level current densities under low overpotentials. Here, we report the use of hydrogen spillover-bridged water dissociation/hydrogen formation processes occurring at the synergistically hybridized Ni 3 S 2 /Cr 2 S 3 sites to incapacitate the inhibition effect of high-current-density-induced high hydrogen coverage at the water dissociation site and concurrently promote Volmer/Tafel processes. The mechanistic insights critically important to enable ampere-level current density operation are depicted from the experimental and theoretical studies. The Volmer process is drastically boosted by the strong H 2 O adsorption at Cr 5c sites of Cr 2 S 3, the efficient H 2 O* dissociation via a heterolytic cleavage process (Cr 5c -H 2 O* + S 3c (#) → Cr 5c -OH* + S 3c -H # ) on the Cr 5c /S 3c sites in Cr 2 S 3, and the rapid desorption of OH* from Cr 5c sites of Cr 2 S 3 via a new water-assisted…

Na-ion layered oxide cathodes (Na x TMO 2, TM = transition metal ion(s)), as an analogue of lithium layered oxide cathodes (such as LiCoO 2, LiNi x Co y Mn 1– x – y O 2 ), have received growing attention with the development of Na-ion batteries. However, due to the larger Na + radius and stronger Na + –Na + electrostatic repulsion in NaO 2 slabs, some undesired phase transitions are observed in Na x TMO 2 . Herein, we report a high-entropy configuration strategy for Na x TMO 2 cathode materials, in which multicomponent TMO 2 slabs with enlarged interlayer spacing help strengthen the whole skeleton structure of layered oxides through mitigating Jahn–Teller distortion, Na + /vacancy ordering, and lattice parameter changes. The strengthened skeleton structure with a modulated particle morphology dramatically improves the Na + transport kinetics and suppresses intragranular fatigue cracks and TM dissolution, thus leading to highly improved performances. Furthermore, the elaborate high-entropy TMO 2 slabs enhance the TM–O bonding energy to restrain oxygen release and thermal runaway,…

Single clusters have attracted extensive research interest in the field of catalysis. However, achieving a highly uniform dispersion of a single-cluster catalyst is challenging. In this work, for the first time, we present a versatile strategy for uniformly dispersed polyoxometalates (POMs) in covalent organic frameworks (COFs) through confining POM cluster into the regular nanopores of COF by a covalent linkage. These COF-POM composites combine the properties of light absorption, electron transfer, and suitable catalytic active sites; as a result, they exhibit outstanding catalytic activity in artificial photosynthesis: that is, CO 2 photoreduction with H 2 O as the electron donor. Among them, TCOF-MnMo 6 achieved the highest CO yield (37.25 μmol g –1 h –1 with ca. 100% selectivity) in a gas–solid reaction system. Furthermore, a mechanism study based on density functional theory (DFT) calculations demonstrated that the photoinduced electron transfer (PET) process occurs from the COF to the POM, and then CO 2 reduction and H 2 O oxidation occur on the POM and COF, respectively. This…

An ampere-level current density of CO 2 electrolysis is critical to realize the industrial production of multicarbon (C 2+ ) fuels. However, under such a large current density, the poor CO intermediate (*CO) coverage on the catalyst surface induces the competitive hydrogen evolution reaction, which hinders CO 2 reduction reaction (CO 2 RR). Herein, we report reliable ampere-level CO 2 -to-C 2+ electrolysis by heteroatom engineering on Cu catalysts. The Cu-based compounds with heteroatom (N, P, S, O) are electrochemically reduced to heteroatom-derived Cu with significant structural reconstruction under CO 2 RR conditions. It is found that N-engineered Cu (N–Cu) catalyst exhibits the best CO 2 -to-C 2+ productivity with a remarkable Faradaic efficiency of 73.7% under −1100 mA cm –2 and an energy efficiency of 37.2% under −900 mA cm –2 . Particularly, it achieves a C 2+ partial current density of −909 mA cm –2 at −1.15 V versus reversible hydrogen electrode, which outperforms most reported Cu-based catalysts. In situ spectroscopy indicates that heteroatom engineering adjusts *CO…

The development of a dynamic chemistry toolbox to endow materials dynamic behavior has been key to the rational design of future smart materials. The rise of supramolecular and dynamic covalent chemistry offers many approaches to the construction of dynamic polymers and materials that can adapt, respond, repair, and recycle. Within this toolbox, the building blocks based on 1,2-dithiolanes have become an important scaffold, featuring their reversible polymerization mediated by dynamic covalent disulfide bonds, which enables a unique class of dynamic materials at the intersection of supramolecular polymers and adaptable covalent networks. This Perspective aims to explore the dynamic chemistry of 1,2-dithiolanes as a versatile structural unit for the design of smart materials by summarizing the state of the art as well as providing an overview of the fundamental challenges involved in this research area and its potential future directions.

Rechargeable aqueous Zn metal batteries have become promising candidates for large-scale electrochemical energy storage owing to their high safety and affordable low cost. However, Zn metal anode suffers from dendritic growth and hydrogen evolution reaction (HER), deteriorating the electrochemical performance. Here, we demonstrate that these challenges can be conquered by introducing a halogen ion into the Zn 2+ solvation structure. By designing an electrolyte composed of zinc acetate and ammonium halide, the electron-donating anion I – can coordinate with Zn 2+ and transform the traditional Zn(H 2 O) 6 2+ to ZnI(H 2 O) 5 +, in which I – could transfer electrons into H 2 O and thus suppress HER. The dynamic electrostatic shielding layer formed by concomitant NH 4 + can restrict the dendritic growth. As a result, the halogenated electrolyte achieves a high initial coulombic efficiency (CE) of 99.3% in the Zn plating/stripping process and remains at an average of ∼99.8% with uniform Zn deposition. Moreover, Zn–I batteries are constructed by using dissociative I – as the cathode and…

Zinc-iodine batteries are promising energy storage devices with the unique features of aqueous electrolytes and safer zinc. However, their performances are still limited by the polyiodide shuttle and the unclear redox mechanism of iodine species. Herein, a single iron atom was embedded in porous carbon with the atomic bridging structure of metal-nitrogen-carbon to not only enhance the confinement effect but also invoke the electrocatalytic redox conversion of iodine, thereby enabling the large capacity and good cycling stability of the zinc-iodine battery. In addition to the physical trapping effect of porous carbon with good electronic conductivity, the in situ experimental characterization and theoretical calculation reveal that the metal-nitrogen-carbon bridging structure modulates the electronic properties of carbon and adjusts the intrinsic activity for the reversible conversion of iodine via the thermodynamically favorable pathway. This work demonstrates that the physicochemical confinement effect can be invoked by the rational anchoring of a single metal atom with nitrogen in…

Artificial photosynthesis of H 2 O 2 from O 2 reduction provides an energy-saving, safe, and green approach. However, it is still critical to develop highly active and selective 2e – oxygen reduction reaction photocatalysts for efficient H 2 O 2 production owing to the unsatisfactory photosynthesis productivity. Herein, two new two-dimensional piperazine-linked CoPc-based covalent organic frameworks (COFs), namely, CoPc-BTM-COF and CoPc-DAB-COF, were afforded from the nucleophilic substitution reaction of hexadecafluorophthalocyaninato cobalt(II) (CoPcF 16 ) with 1,2,4,5-benzenetetramine (BTM) or 3,3′-diaminobenzidine (DAB). Powder X-ray diffraction analysis in combination with electron microscopy and a series of spectroscopic technologies reveals their crystalline porous framework with a fully conjugated structure and eclipsed π-stacking model. Ultraviolet–visible diffuse reflectance absorption spectra unveil their excellent light absorption capacity in a wide range of 400–1000 nm. This, together with their enhanced photo-induced charge separation and transport efficiency as…

Promoting the oxygen evolution reaction (OER) with saline water is highly desired to realize seawater splitting. This requires OER catalysts to resist serious corrosion and undesirable chloride oxidation. We introduce a 5d transition metal, Ir, to develop a monolayer NiIr-layered double hydroxide (NiIr-LDH) as the catalyst with enhanced OER performance for seawater splitting. The NiIr-LDH catalyst delivers 500 mA/cm 2 at only 361 mV overpotential with ∼99% O 2 Faradaic efficiency in alkaline seawater, which is more active than commercial IrO 2 (763 mV, 23%) and the best known OER catalyst NiFe-LDH (530 mV, 92%). Moreover, it shows negligible activity loss at up to 650 h chronopotentiometry measurements at an industrial level (500 mA/cm 2 ), while commercial IrO 2 and NiFe-LDH rapidly deactivated within 0.2 and 10 h, respectively. The incorporation of Ir into the Ni(OH) 2 layer greatly altered the electron density of Ir and Ni sites, which was revealed by X-ray absorption fine structure and density functional theory (DFT) calculations. Coupling the electrochemical measurements and in…

Electrocatalytic reactions occur in the nanoscale space at the electrified electrode–electrolyte interface. It is well known that the electrode–electrolyte interface, also called as interfacial microenvironment, is difficult to investigate due to the interference of bulk electrolytes and its dynamic evolution in response to applied bias potential. Here, we employ electrochemical co-reduction of CO 2 and H 2 O on commercial Ag electrodes as a model system, in conjunction with quaternary ammonium cationic surfactants as electrolyte additives. We probe bias-potential-driven dynamic response of the interfacial microenvironment as well as the mechanistic origin of catalytic selectivity. By virtue of comprehensive in situ vibrational spectroscopy, electrochemical impedance spectroscopy, and molecular dynamics simulations, it is revealed that the structure of surfactants is dynamically changed from a random distribution to a nearly ordered assembly with increasing bias potential. The nearly ordered surfactant assembly regulates the interfacial water environment by repelling isolated water…

Single-atom catalysts based on metal–N 4 moieties and anchored on carbon supports (defined as M–N–C) are promising for oxygen reduction reaction (ORR). Among those, M–N–C catalysts with 4d and 5d transition metal (TM 4d,5d ) centers are much more durable and not susceptible to the undesirable Fenton reaction, especially compared with 3d transition metal based ones. However, the ORR activity of these TM 4d,5d –N–C catalysts is still far from satisfactory; thus far, there are few discussions about how to accurately tune the ligand fields of single-atom TM 4d,5d sites in order to improve their catalytic properties. Herein, we leverage single-atom Ru–N–C as a model system and report an S-anion coordination strategy to modulate the catalyst’s structure and ORR performance. The S anions are identified to bond with N atoms in the second coordination shell of Ru centers, which allows us to manipulate the electronic configuration of central Ru sites. The S-anion-coordinated Ru–N–C catalyst delivers not only promising ORR activity but also outstanding long-term durability, superior to those…

Encapsulation of metal nanoparticles by support-derived materials known as the classical strong metal–support interaction (SMSI) often happens upon thermal treatment of supported metal catalysts at high temperatures (≥500 °C) and consequently lowers the catalytic performance due to blockage of metal active sites. Here, we show that this SMSI state can be constructed in a Ru–MoO 3 catalyst using CO 2 hydrogenation reaction gas and at a low temperature of 250 °C, which favors the selective CO 2 hydrogenation to CO. During the reaction, Ru nanoparticles facilitate reduction of MoO 3 to generate active MoO 3– x overlayers with oxygen vacancies, which migrate onto Ru nanoparticles’ surface and form the encapsulated structure, that is, Ru@MoO 3– x . The formed SMSI state changes 100% CH 4 selectivity on fresh Ru particle surfaces to above 99.0% CO selectivity with excellent activity and long-term catalytic stability. The encapsulating oxide layers can be removed via O 2 treatment, switching back completely to the methanation. This work suggests that the encapsulation of metal…

Anchoring platinum catalysts on appropriate supports, e.g., MXenes, is a feasible pathway to achieve a desirable anode for direct methanol fuel cells. The authentic performance of Pt is often hindered by the occupancy and poisoning of active sites, weak interaction between Pt and supports, and the dissolution of Pt. Herein, we construct three-dimensional (3D) crumpled Ti 3 C 2 T x MXene balls with abundant Ti vacancies for Pt confinement via a spray-drying process. The as-prepared Pt clusters/Ti 3 C 2 T x (Ptc/Ti 3 C 2 T x ) show enhanced electrocatalytic methanol oxidation reaction (MOR) activity, including a relatively low overpotential, high tolerance to CO poisoning, and ultrahigh stability. Specifically, it achieves a high mass activity of up to 7.32 A mg Pt –1, which is the highest value reported to date in Pt-based electrocatalysts, and 42% of the current density is retained on Ptc/Ti 3 C 2 T x even after the 3000 min operative time. In situ spectroscopy and theoretical calculations reveal that an electric field-induced repulsion on the Ptc/Ti 3 C 2 T x interface accelerates…

We report the first covalent incorporation of reactive aliphatic amine species into covalent organic frameworks (COFs). This was achieved through the crystallization of an imine-linked COF, termed COF-609-Im, followed by conversion of its imine linkage to base-stable tetrahydroquinoline linkage through aza-Diels–Alder cycloaddition, and finally, the covalent incorporation of tris(3-aminopropyl)amine into the framework. The obtained COF-609 exhibits a 1360-fold increase in CO 2 uptake capacity compared to the pristine framework and a further 29% enhancement in the presence of humidity. We confirmed the chemistry of framework conversion and corroborated the enhanced CO 2 uptake phenomenon with and without humidity through isotope-labeled Fourier transform infrared spectroscopy and solid-state nuclear magnetic resonance spectroscopy. With this study, we established a new synthetic strategy to access a class of chemisorbents characterized by high affinity to CO 2 in dilute sources, such as the air.

Saturated bicycles are becoming ever more important in the design and development of new pharmaceuticals. Here a new strategy for the synthesis of bicyclo[2.1.1]hexanes is described. These bicycles are significant because they have defined exit vectors, yet many substitution patterns are underexplored as building blocks. The process involves sensitization of a bicyclo[1.1.0]butane followed by cycloaddition with an alkene. The scope and mechanistic details of the method are discussed.

Metal-organic framework-808 has been functionalized with 11 amino acids (AA) to produce a series of MOF-808-AA structures. The adsorption of CO2 under flue gas conditions revealed that glycine- and DL-lysine-functionalized MOF-808 (MOF-808-Gly and -DL-Lys) have the highest uptake capacities. Enhanced CO2 capture performance in the presence of water was observed and studied using single-component sorption isotherms, CO2/H2O binary isotherm, and dynamic breakthrough measurements. The key to the favorable performance was uncovered by deciphering the mechanism of CO2 capture in the pores and attributed to the formation of bicarbonate as evidenced by 13C and 15N solid-state nuclear magnetic resonance spectroscopy studies. Based on these results, we examined the performance of MOF-808-Gly in simulated coal flue gas conditions and found that it is possible to capture and release CO2 by vacuum swing adsorption. MOF-808-Gly was cycled at least 80 times with full retention of performance. This study significantly advances our understanding of CO2 chemistry in MOFs by revealing how strongly…

High Resolution Image Download MS PowerPoint Slide Chemical recycling is one of the most promising technologies that could contribute to circular economy targets by providing solutions to plastic waste; however, it is still at an early stage of development. In this work, we describe the first light-driven, acid-catalyzed protocol for chemical recycling of polystyrene waste to valuable chemicals under 1 bar of O 2 . Requiring no photosensitizers and only mild reaction conditions, the protocol is operationally simple and has also been demonstrated in a flow system. Electron paramagnetic resonance (EPR) investigations and density functional theory (DFT) calculations indicate that singlet oxygen is involved as the reactive oxygen species in this degradation process, which abstracts a hydrogen atom from a tertiary C–H bond, leading to hydroperoxidation and subsequent C–C bond cracking events via a radical process. Notably, our study indicates that an adduct of polystyrene and an acid catalyst might be formed in situ, which could act as a photosensitizer to initiate the formation of…

Chemical upcycling of polystyrene into targeted small molecules is desirable to reduce plastic pollution. Herein, we report the upcycling of polystyrene to benzoyl products, primarily benzoic acid, using a catalyst-controlled photooxidative degradation method. FeCl 3 undergoes a homolytic cleavage upon irradiation with white light to generate a chlorine radical, abstracting an electron-rich hydrogen atom on the polymer backbone. Under the oxygen-rich environment, high MW polystyrene (>90 kg/mol) degrades down to <1 kg/mol and produces up to 23 mol % benzoyl products. A series of mechanistic studies showed that chlorine radicals promoted the degradation via hydrogen-atom abstraction. Commercial polystyrene degrades efficiently in our method, showing the compatibility of our system with polymer fillers. Finally, we demonstrated the potential of scaling up our approach in a photoflow process to convert gram quantities of PS to benzoic acid.

“Spin” has been recently reported as an important degree of electronic freedom to improve the performance of electrocatalysts and photocatalysts. This work demonstrates the manipulations of spin-polarized electrons in CsPbBr 3 halide perovskite nanoplates (NPLs) to boost the photocatalytic CO 2 reduction reaction (CO 2 RR) efficiencies by doping manganese cations (Mn 2+ ) and applying an external magnetic field. Mn-doped CsPbBr 3 (Mn-CsPbBr 3 ) NPLs exhibit an outstanding photocatalytic CO 2 RR compared to pristine CsPbBr 3 NPLs due to creating spin-polarized electrons after Mn doping. Notably, the photocatalytic CO 2 RR of Mn-CsPbBr 3 NPLs is significantly enhanced by applying an external magnetic field. Mn-CsPbBr 3 NPLs exhibit 5.7 times improved performance of photocatalytic CO 2 RR under a magnetic field of 300 mT with a permanent magnet compared to pristine CsPbBr 3 NPLs. The corresponding mechanism is systematically investigated by magnetic circular dichroism spectroscopy, ultrafast transient absorption spectroscopy, and density functional theory simulation. The origin of…

Stretchable polymer semiconductors have advanced rapidly in the past decade as materials required to realize conformable and soft skin-like electronics become available. Through rational molecular-level design, stretchable polymer semiconductor films are now able to retain their electrical functionalities even when subjected to repeated mechanical deformations. Furthermore, their charge-carrier mobilities are on par with the best flexible polymer semiconductors, with some even exceeding that of amorphous silicon. The key advancements are molecular-design concepts that allow multiple strain energy-dissipation mechanisms, while maintaining efficient charge-transport pathways over multiple length scales. In this perspective article, we review recent approaches to confer stretchability to polymer semiconductors while maintaining high charge carrier mobilities, with emphasis on the control of both polymer-chain dynamics and thin-film morphology. Additionally, we present molecular design considerations toward intrinsically elastic semiconductors that are needed for reliable device…

The development of high-efficiency and durable bifunctional electrocatalysts for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is critical for the widespread application of rechargeable zinc–air (Zn–air) batteries. This calls for rational screening of targeted ORR/OER components and precise control of their atomic and electronic structures to produce synergistic effects. Here, we report a Mn-doped RuO 2 (Mn-RuO 2 ) bimetallic oxide with atomic-scale dispersion of Mn atoms into the RuO 2 lattice, which exhibits remarkable activity and super durability for both the ORR and OER, with a very low potential difference (Δ E ) of 0.64 V between the half-wave potential of ORR ( E 1/2 ) and the OER potential at 10 mA cm –2 ( E j 10 ) and a negligible decay of E 1/2 and E j 10 after 250 000 and 30 000 CV cycles for ORR and OER, respectively. Moreover, Zn–air batteries using the Mn-RuO 2 catalysts exhibit a high power density of 181 mW cm –2, low charge/discharge voltage gaps of 0.69/0.96/1.38 V, and ultralong lifespans of 15 000/2800/1800 cycles (corresponding to…

Developing highly active, selective, and stable electrocatalysts for the carbon dioxide reduction reaction (CO 2 RR) is crucial to establish a CO 2 conversion system for industrial implementation and, therefore, to realize an artificially closed carbon loop. This can only be achieved through the rational material design based upon the knowledge of the operational active site at the molecular scale. Enlightened by theoretical screening, herein, we for the first time manipulate a novel Ni–Cu atomic pair configuration toward improved CO 2 RR performance. Systematic characterizations and theoretical modeling reveal that the secondary Cu metal incorporation positively shifts the Ni 3d orbital energy to the Fermi level and thus accelerates the rate-determining step, *COOH formation. In addition, the intrinsic inactivity of Cu toward the competing hydrogen evolution reaction causes a considerable reaction barrier for water dissociation on the Ni–Cu moiety. Due to these attributes, the as-developed Ni/Cu–N–C catalyst exhibits excellent catalytic activity and selectivity, with a record-high…

The coordinated configuration of atomic platinum (Pt) has always been identified as an active site with high intrinsic activity for hydrogen evolution reaction (HER). Herein, we purposely synthesize single vacancies in a carbon matrix (defective graphene) that can trap atomic Pt to form the Pt–C 3 configuration, which gives exceptionally high reactivity for HER in both acidic and alkaline solutions. The intrinsic activity of Pt–C 3 site is valued with a turnover frequency (TOF) of 26.41 s –1 and mass activity of 26.05 A g –1 at 100 mV, respectively, which are both nearly 18 times higher than those of commercial 20 wt % Pt/C. It is revealed that the optimal coordination Pt–C 3 has a stronger electron-capture ability and lower Gibbs free energy difference (Δ G ), resulting in promoting the reduction of adsorbed H + and the acceleration of H 2 desorption, thus exhibiting the extraordinary HER activity. This work provides a new insight on the unique coordinated configuration of dispersive atomic Pt in defective C matrix for superior HER performance.

The long-term stability of single-atom catalysts is a major factor affecting their large-scale commercial application. How to evaluate the dynamic stability of single-atom catalysts under working conditions is still lacking. Here, taking a single copper atom embedded in N-doped graphene as an example, the “constant-potential hybrid-solvation dynamic model” is used to evaluate the reversible transformation between copper single atoms and clusters under realistic reaction conditions. It is revealed that the adsorption of H is a vital driving force for the leaching of the Cu single atom from the catalyst surface. The more negative the electrode potential, the stronger the adsorption of H. As a result, the competitive hydrogen evolution reaction is inhibited, and Cu–N bonds are weakened, resulting in some Cu atoms being tethered on the catalyst surface and some being dissolved in the aqueous solution. The collision of the Cu atoms in the two states forms a transient Cu cluster structure as a true catalytic active site to promote CO 2 reduction to ethanol. As the applied potential is…

Electrochemical CO 2 reduction is a promising way to mitigate CO 2 emissions and close the anthropogenic carbon cycle. Among products from CO 2 RR, multicarbon chemicals, such as ethylene and ethanol with high energy density, are more valuable. However, the selectivity and reaction rate of C 2 production are unsatisfactory due to the sluggish thermodynamics and kinetics of C–C coupling. The electric field and thermal field have been studied and utilized to promote catalytic reactions, as they can regulate the thermodynamic and kinetic barriers of reactions. Either raising the potential or heating the electrolyte can enhance C–C coupling, but these come at the cost of increasing side reactions, such as the hydrogen evolution reaction. Here, we present a generic strategy to enhance the local electric field and temperature simultaneously and dramatically improve the electric–thermal synergy desired in electrocatalysis. A conformal coating of ∼5 nm of polytetrafluoroethylene significantly improves the catalytic ability of copper nanoneedles (∼7-fold electric field and ∼40 K temperature…

Aqueous-phase oxygen evolution reaction (OER) is the bottleneck of water splitting. The formation of the O–O bond involves the generation of paramagnetic oxygen molecules from the diamagnetic hydroxides. The spin configurations might play an important role in aqueous-phase molecular electrocatalysis. However, spintronic electrocatalysis is almost an uncultivated land for the exploration of the oxygen molecular catalysis process. Herein, we present a novel magnetic Fe III site spin-splitting strategy, wherein the electronic structure and spin states of the Fe III sites are effectively induced and optimized by the Jahn–Teller effect of Cu 2+ . The theoretical calculations and operando attenuated total reflectance-infrared Fourier transform infrared (ATR FT-IR) reveal the facilitation for the O–O bond formation, which accelerates the production of O 2 from OH – and improves the OER activity. The Cu 1 –Ni 6 Fe 2 –LDH catalyst exhibits a low overpotential of 210 mV at 10 mA cm –2 and a low Tafel slope (33.7 mV dec –1 ), better than those of the initial Cu 0 –Ni 6 Fe 2 –LDHs (278 mV,…

In chemical biology research, various fluorescent probes have been developed and used to visualize target proteins or molecules in living cells and tissues, yet there are limitations to this technology, such as the limited number of colors that can be detected simultaneously. Recently, Raman spectroscopy has been applied in chemical biology to overcome such limitations. Raman spectroscopy detects the molecular vibrations reflecting the structures and chemical conditions of molecules in a sample and was originally used to directly visualize the chemical responses of endogenous molecules. However, our initial research to develop "Raman tags" opens a new avenue for the application of Raman spectroscopy in chemical biology. In this Perspective, we first introduce the label-free Raman imaging of biomolecules, illustrating the biological applications of Raman spectroscopy. Next, we highlight the application of Raman imaging of small molecules using Raman tags for chemical biology research. Finally, we discuss the development and potential of Raman probes, which represent the…

Solar-driven water generation is a sustainable water treatment technology, helping to relieve global water scarcity issues. However, this technology faces great challenges due to the high energy consumption of water evaporation yielding low evaporation rates. Here, a covalent organic framework (COF)/graphene dual-region hydrogel, containing hydrophilic and hydrophobic regions in one material, is developed through a facile in situ growth strategy. The hydrophilic COF is covering parts of the hydrophobic graphene regions. Through accurate control of both wetting regions, the hybrid hydrogel shows effective light-harvesting, tunable wettability, optimized water content, and lowered energy demand for water vaporization. Acting as solar absorber, the dual-region hydrogel exhibits a steam generation rate as high as 3.69 kg m –2 h –1 under 1 sun irradiation (1 kW m –2 ), which competes well with other state-of-the-art materials. Furthermore, this hydrogel evaporator can be used to produce drinkable water from seawater and sewage, demonstrating the potential for water treatment.

Late-stage functionalization of C-H bonds (C-H LSF) can provide a straightforward approach to the efficient synthesis of functionalized complex molecules. However, C-H LSF is challenging because the C-H bond must be functionalized in the presence of various other functional groups. In this Perspective, we evaluate aromatic C-H LSF on the basis of four criteria─reactivity, chemoselectivity, site-selectivity, and substrate scope─and provide our own views on current challenges as well as promising strategies and areas of growth going forward.

The need for enhanced energy storage and improved catalysts has led researchers to explore advanced functional materials for sustainable energy production and storage. Herein, we demonstrate a reductive electrosynthesis approach to prepare a layer-by-layer (LbL) assembled trimetallic Fe–Co–Ni metal–organic framework (MOF) in which the metal cations within each layer or at the interface of the two layers are linked to one another by bridging 2-amino-1,4-benzenedicarboxylic acid linkers. Tailoring catalytically active sites in an LbL fashion affords a highly porous material that exhibits excellent trifunctional electrocatalytic activities toward the hydrogen evolution reaction (η j =10 = 116 mV), oxygen evolution reaction (η j =10 = 254 mV), as well as oxygen reduction reaction (half-wave potential = 0.75 V vs reference hydrogen electrode) in alkaline solutions. The dispersion-corrected density functional theory calculations suggest that the prominent catalytic activity of the LbL MOF toward the HER, OER, and ORR is due to the initial negative adsorption energy of water on the metal…

Fe–N–C electrocatalysts have emerged as promising substitutes for Pt-based catalysts for the oxygen reduction reaction (ORR). However, their real catalytic active site is still under debate. The underlying roles of different types of coordinating N including pyridinic and pyrrolic N in catalytic performance require thorough clarification. In addition, how to understand the pH-dependent activity of Fe–N–C catalysts is another urgent issue. Herein, we comprehensively studied 13 different N-coordinated FeN x C configurations and their corresponding ORR activity through simulations which mimic the realistic electrocatalytic environment on the basis of constant-potential implicit solvent models. We demonstrate that coordinating pyrrolic N contributes to a higher activity than pyridinic N, and pyrrolic FeN 4 C exhibits the highest activity in acidic media. Meanwhile, the in situ active site transformation to *O-FeN 4 C and *OH-FeN 4 C clarifies the origin of the higher activity of Fe–N–C in alkaline media. These findings can provide indispensable guidelines for rational design of better…

Purification of C 2 H 4 from a ternary C 2 H 2 /C 2 H 6 /C 2 H 4 mixture by one-step adsorption separation is of prime importance but challenging in the petrochemical industry; however, effective strategies to design high-performance adsorbents are lacking. We herein report for the first time the incorporation of Lewis basic sites into a C 2 H 6 -selective MOF, enabling efficient one-step production of polymer-grade C 2 H 4 from ternary mixtures. Introduction of amino groups into highly stable C 2 H 6 -selective UiO-67 can not only partition large pores into smaller cagelike pockets to provide suitable pore confinement but also offer additional binding sites to simultaneously enhance C 2 H 2 and C 2 H 6 adsorption capacities over C 2 H 4 . The amino-functionalized UiO-67-(NH 2 ) 2 thus exhibits exceptionally high C 2 H 2 and C 2 H 6 uptakes as well as benchmark C 2 H 2 /C 2 H 4 and C 2 H 6 /C 2 H 4 selectivities, surpassing all of the C 2 H 2 /C 2 H 6 -selective materials reported so far. Theoretical calculations combined with in situ infrared spectroscopy indicate that the…

The compositional space of high-entropy-alloy nanoparticles (HEA NPs) significantly expands the diversity of the materials library. Every atom in HEA NPs has a different elemental coordination environment, which requires knowledge of the local electronic structure at an atomic level. However, such structure has not been disclosed experimentally or theoretically. We synthesized HEA NPs composed of all eight noble-metal-group elements (NM-HEA) for the first time. Their electronic structure was revealed by hard X-ray photoelectron spectroscopy and density function theory calculations with NP models. The NM-HEA NPs have a lower degeneracy in energy level compared with the monometallic NPs, which is a common feature of HEA NPs. The local density of states (LDOS) of every surface atom was first revealed. Some atoms of the same constituent element in HEA NPs have different LDOS profiles, whereas atoms of other elements have similar LDOS profiles. In other words, one atom in HEA loses its elemental identity and it may be possible to create an ideal LDOS by adjusting the neighboring atoms.…

Chronic wound is a common complication for diabetic patients, which entails substantial inconvenience, persistent pain, and significant economic burden to patients. However, current clinical treatments for diabetic chronic wounds remain unsatisfactory. A prolonged but ineffective inflammation phase in chronic wounds is the primary difference between diabetic chronic wounds and normal wounds. Herein, we present an effective antioxidative system (MOF/Gel) for chronic wound healing of diabetic rats through integrating a metal organic framework (MOF) nanozyme with antioxidant enzyme-like activity with a hydrogel (Gel). MOF/Gel can continuously scavenge reactive oxygen species to modulate the oxidative stress microenvironment in diabetic chronic wounds, which leads to a natural transition from the inflammation phase to the proliferation phase. Impressively, the efficacy of one-time-applied MOF/Gel was comparable to that of the human epidermal growth factor Gel, a widely used clinical drug for various wound treatments. Such an effective, safe, and convenient MOF/Gel system can meet…

Photoelectrocatalytic (PEC) glycerol oxidation offers a sustainable approach to produce dihydroxyacetone (DHA) as a valuable chemical, which can find use in cosmetic, pharmaceutical industries, etc. However, it still suffers from the low selectivity (≤60%) that substantially limits the application. Here, we report the PEC oxidation of glycerol to DHA with a selectivity of 75.4% over a heterogeneous photoanode of Bi 2 O 3 nanoparticles on TiO 2 nanorod arrays (Bi 2 O 3 /TiO 2 ). The selectivity of DHA can be maintained at ∼65% under a relatively high conversion of glycerol (∼50%). The existing p–n junction between Bi 2 O 3 and TiO 2 promotes charge transfer and thus guarantees high photocurrent density. Experimental combined with theoretical studies reveal that Bi 2 O 3 prefers to interact with the middle hydroxyl of glycerol that facilitates the selective oxidation of glycerol to DHA. Comprehensive reaction mechanism studies suggest that the reaction follows two parallel pathways, including electrophilic OH* (major) and lattice oxygen (minor) oxidations. Finally, we designed a…

As cut-outs from a graphene sheet, nanographenes (NGs) and graphene nanoribbons (GNRs) are ideal cases with which to connect the world of molecules with that of bulk carbon materials. While various top-down approaches have been developed to produce such nanostructures in high yields, in the present perspective, precision structural control is emphasized for the length, width, and edge structures of NGs and GNRs achieved by modern solution and on-surface syntheses. Their structural possibilities have been further extended from "flatland" to the three-dimensional world, where chirality and handedness are the jewels in the crown. In addition to properties exhibited at the molecular level, self-assembly and thin-film structures cannot be neglected, which emphasizes the importance of processing techniques. With the rich toolkit of chemistry in hand, NGs and GNRs can be endowed with versatile properties and functions ranging from stimulated emission to spintronics and from bioimaging to energy storage, thus demonstrating their multitalents in present and future materials science.

High-entropy alloys (HEAs) are attracting intensive attention due to their broad compositional tunability and interesting catalytic properties. However, precisely shaping the HEAs into suprathin low-dimensional nanostructures for achieving diverse applications remains an enormous challenge owing to their intrinsic thermodynamic instability. Herein we propose a new and general low-temperature method for incorporating up to eight metallic elements into one single-phase subnanometer ribbon to achieve the thinnest HEA metal materials in the world. We experimentally demonstrate that synthetic processes for suprathin HEA subnanometer ribbons (SNRs) include (1) different metal atom nucleation via galvanic exchange reaction between different metal precursors and Ag nanowire template, (2) co-reduction of different metal precursors on nanowire template, and (3) the removal of the inner Ag core. Density functional theory (DFT) calculations reveal that the crystallization and stabilization of HEA SNRs strongly depend on the “highly dynamic” Ag from the template, and the crystallization levels…

The design of molecular catalysts typically involves reconciling multiple conflicting property requirements, largely relying on human intuition and local structural searches. However, the vast number of potential catalysts requires pruning of the candidate space by efficient property prediction with quantitative structure–property relationships. Data-driven workflows embedded in a library of potential catalysts can be used to build predictive models for catalyst performance and serve as a blueprint for novel catalyst designs. Herein we introduce kraken, a discovery platform covering monodentate organophosphorus(III) ligands providing comprehensive physicochemical descriptors based on representative conformer ensembles. Using quantum-mechanical methods, we calculated descriptors for 1558 ligands, including commercially available examples, and trained machine learning models to predict properties of over 300000 new ligands. We demonstrate the application of kraken to systematically explore the property space of organophosphorus ligands and how existing data sets in catalysis can be…

Electrocatalysis is a promising approach to convert waste nitrate to ammonia and help close the nitrogen cycle. This renewably powered ammonia production process sources hydrogen from water (as opposed to methane in the thermal Haber–Bosch process) but requires a delicate balance between a catalyst’s activity for the hydrogen evolution reaction (HER) and the nitrate reduction reaction (NO 3 RR), influencing the Faradaic efficiency (FE) and selectivity to ammonia/ammonium over other nitrogen-containing products. We measure ammonium FEs ranging from 3.6 ± 6.6% (on Ag) to 93.7 ± 0.9% (on Co) across a range of transition metals (TMs; Ti, Fe, Co, Ni, Ni 0.68 Cu 0.32, Cu, and Ag) in buffered neutral media. To better understand these competing reaction kinetics, we develop a microkinetic model that captures the voltage-dependent nitrate rate order and illustrates its origin as competitive adsorption between nitrate and hydrogen adatoms (H*). NO 3 RR FE can be described via competition for electrons with the HER, decreasing sharply for TMs with a high work function and a correspondingly…

Tumor-derived exosome can suppress dendritic cells (DCs) and T cells functions. Excessive secretion of exosomal programmed death-ligand 1 (PD-L1) results in therapeutic resistance to PD-1/PD-L1 immunotherapy and clinical failure. Restored T cells by antiexosomal PD-L1 tactic can intensify ferroptosis of tumor cells and vice versa. Diminishing exosomal suppression and establishing a nexus of antiexosomal PD-L1 and ferroptosis may rescue the discouraging antitumor immunity. Here, we engineered phototheranostic metal-phenolic networks (PFG MPNs) by an assembly of semiconductor polymers encapsulating ferroptosis inducer (Fe 3+ ) and exosome inhibitor (GW4869). The PFG MPNs elicited superior near-infrared II fluorescence/photoacoustic imaging tracking performance for a precise photothermal therapy (PTT). PTT-augmented immunogenic cell death relieved exosomal silencing on DC maturation. GW4869 mediated PD-L1 based exosomal inhibition revitalized T cells and enhanced the ferroptosis. This novel synergy of PTT with antiexosomal PD-L1 enhanced ferroptosis evoked potent antitumor immunity in…

The practical utilization of covalent organic frameworks (COFs) with manipulation at the atomic and molecular scale often demands their assembly on the nano-, meso-, and macroscale with precise control. Consequently, synthetic approaches that establish the ability to control the nucleation and growth of COF crystallites and their self-assembly to desired COF nanomorphologies have drawn substantial attention from researchers. On the basis of the dimensionality of the COF morphologies, we can categorize them into zero- (0-D), one- (1-D), two- (2-D), and three-dimensional (3-D) nanomorphologies. In this perspective, we summarize the reported synthetic strategies that enable precise control of the COF nanomorphologies' size, shape, and dimensionality and reveal the impact of the dimensionalities in their physicochemical properties and applications. The aim is to establish a synergistic optimization of the morphological dimensionality while keeping the micro- or mesoporosity, crystallinity, and chemical functionalities of the COFs in perspective. A detailed knowledge along the way should…

Ruthenium-based materials are considered great promising candidates to replace Pt-based catalysts for hydrogen production in alkaline conditions. Herein, we adopt a facile method to rationally design a neoteric Schottky catalyst in which uniform ultrafine ruthenium nanoparticles featuring lattice compressive stress are supported on nitrogen-modified carbon nanosheets (Ru NPs/NC) for efficient hydrogen evolution reaction (HER). Lattice strain and Schottky junction dual regulation ensures that the Ru NPs/NC catalyst with an appropriate nitrogen content displays superb H 2 evolution in alkaline media. Particularly, Ru NPs/NC-900 with 1.3% lattice compressive strain displays attractive activity and durability for the HER with a low overpotential of 19 mV at 10 mA cm –2 in 1.0 M KOH electrolyte. The in situ X-ray absorption fine structure measurements indicate that the low-valence Ru nanoparticle with shrinking Ru–Ru bond acts as catalytic active site during the HER process. Furthermore, multiple spectroscopy analysis and density functional theory calculations demonstrate that the…

Fluorescence imaging in the second near-infrared window (NIR-II, 1000-1700 nm) using small-molecule dyes has high potential for clinical use. However, many NIR-II dyes suffer from the emission quenching effect and extremely low quantum yields (QYs) in the practical usage forms. The AIE strategy has been successfully utilized to develop NIR-II dyes with donor-acceptor (D-A) structures with acceptable QYs in the aggregate state, but there is still large room for QY improvement. Here, we rationally designed a NIR-II emissive dye named TPE-BBT and its derivative (TPEO-BBT) by changing the electron-donating triphenylamine unit to tetraphenylethylene (TPE). Their nanoparticles exhibited ultrahigh relative QYs of 31.5% and 23.9% in water, respectively. By using an integrating sphere, the absolute QY of TPE-BBT nanoparticles was measured to be 1.8% in water. Its crystals showed an absolute QY of 10.4%, which is the highest value among organic small molecules reported so far. The optimized D-A interaction and the higher rigidity of TPE-BBT in the aggregate state are believed to be the two…

Solar-driven photocatalytic reactions can mildly activate hydrocarbon C–H bonds to produce value-added chemicals. However, the inefficient utilization of photogenerated carriers hinders the application. Here, we report reversible photochromic BiOBr (denoted as p -BiOBr) nanosheets that were colored by trapping photogenerated holes upon visible light irradiation and bleached by water oxidation to generate hydroxyl radicals, demonstrating enhanced carrier separation and water oxidation. The photocatalytic coupling and oxidation reactions of ethylbenzene were efficiently realized by p -BiOBr in a water-based medium under ambient temperature and pressure (apparent quantum yield is 14 times that of pristine BiOBr). The p -BiOBr nanosheets feature lattice disordered defects on the surface, providing rich uncoordinated catalytic sites and inducing structural distortions and lattice strain, which further leads to an altered band structure and significantly enhanced photocatalytic performances. These hole-trapping materials open up the possibility of substantially elevating the utilization…

Visible-light photocatalysis and electrocatalysis are two powerful strategies for the promotion of chemical reactions that have received tremendous attention in recent years. In contrast, processes that combine these two modalities, an area termed electrophotocatalysis, have until recently remained quite rare. However, over the past several years a number of reports in this area have shown the potential of combining the power of light and electrical energy to realize new catalytic transformations. Electrophotocatalysis offers the ability to perform photoredox reactions without the need for large quantities of stoichiometric or superstoichiometric chemical oxidants or reductants by making use of an electrochemical potential as the electron source or sink. In addition, electrophotocatalysis is readily amenable to the generation of open-shell photocatalysts, which tend to have exceptionally strong redox potentials. In this way, potent yet selective redox reactions have been realized under relatively mild conditions. This Perspective highlights recent advances in the area of…

Pyroptosis, a newly characterized form of immunogenic cell death, is attracting increasing attention as a promising approach to cancer immunotherapy. However, biocompatible strategies to activate pyroptosis remain rare. Here, we show that a photocatalytic superoxide radical (O 2 –• ) generator, NI-TA, triggers pyroptosis in cancer cells. NI-TA was designed to take advantage of an intramolecular triplet-ground state splitting energy modulation approach. Detailed studies revealed that the pyroptosis triggered by NI-TA under conditions of photoexcitation proceeds through a caspase-3/gasdermin E (GSDME) pathway rather than via canonical processes involving caspase-1/gasdermin-D (GSDMD). NI-TA was found to function via a partial-O 2 -recycling mode of action and to trigger cell pyroptosis and provide for effective cancer cell ablation even under conditions of hypoxia (≤2% O 2 ). In the case of T47D 3D multicellular spheroids, good antitumor efficiency and stemness inhibition are achieved. This work highlights how photocatalytic chemistry may be leveraged to develop effective…

An inconvenient hurdle in the practice of nanomedicine is the protein corona, a spontaneous collection of biomolecular species by nanoparticles in living systems. The protein corona is dynamic in composition and may entail improved water suspendability and compromised delivery and targeting to the nanoparticles. How much of this nonspecific protein ensemble is determined by the chemistry of the nanoparticle core and its surface functionalization, and how much of this entity is dictated by the biological environments that vary spatiotemporally in vivo? How do we “live with” and exploit the protein corona without significantly sacrificing the efficacy of nanomedicines in diagnosing and curing human diseases? This article discusses the chemical and biophysical signatures of the protein corona and ponders challenges ahead for the field of nanomedicine.

B–N-fused dianthracenylpyrazine derivatives are synthesized to generate new low gap chromophores. Photophysical and electrochemical, crystal packing, and theoretical studies have been performed. Two energetically similar conformers are identified by density functional theory calculations, showing that the core unit adopts a curved saddle-like shape ( x-isomer ) or a zig-zag conformation ( z-isomer ). In the solid state, the z-isomer is prevalent according to an X-ray crystal structure of a C 6 F 5 -substituted derivative ( 4-Pf ), but variable-temperature nuclear magnetic resonance studies suggest a dynamic behavior in solution. B–N fusion results in a large decrease of the HOMO–LUMO gap and dramatically lowers the LUMO energy compared to the all-carbon analogues. 4-Pf in particular shows significant absorbance at greater than 700 nm while being almost transparent throughout the visible region. After encapsulation in the biodegradable polymer DSPE-mPEG 2000, 4-Pf nanoparticles ( 4-Pf-NPs ) exhibit good water solubility, high photostability, and an excellent photothermal conversion…

The capture of radioactive I 2 vapor from nuclear waste under industrial operating conditions remains a challenging task, as the practical industrial conditions of high temperature (≥150 °C) and low I 2 concentration (∼150 ppmv) are unfavorable for I 2 adsorption. We report a novel guanidinium-based covalent organic framework (COF), termed TGDM, which can efficiently capture I 2 under industrial operating conditions. At 150 °C and 150 ppmv I 2, TGDM exhibits an I 2 uptake of ∼30 wt %, which is significantly higher than that of the industrial silver-based adsorbents such as Ag@MOR (17 wt %) currently used in the nuclear fuel reprocessing industry. Characterization and theoretical calculations indicate that among the multiple types of adsorption sites in TGDM, only ionic sites can bond to I 2 through strong Coulomb interactions under harsh conditions. The abundant ionic groups of TGDM account for its superior I 2 capture performance compared to various benchmark adsorbents. In addition, TGDM exhibits exceptionally high chemical and thermal stabilities that fully meet the requirements…

Developing cost-/energy-efficient separation techniques for purifying ethylene from an ethylene/ethane mixture is highly important but very challenging in the industrial process. Herein, using a bottom-up [8 + 2] construction approach, we rationally designed and synthesized three three-dimensional covalent organic frameworks (COFs) with 8-connected bcu networks, which can selectively remove ethane from an ethylene/ethane mixture with high efficiency. These COF materials, which are fabricated by the condensation reaction of a customer-designed octatopic aldehyde monomer with linear diamino linkers, possess high crystallinity, good structural robustness, and high porosity. Attributed to the well-organized micro-sized pores with a nonpolar/inert pore environment, these COFs display high ethane adsorption capacity and good selectivity over ethylene, making them among the best ethane-selective adsorbents for ethylene purification. Their excellent ethylene/ethane separation performance is validated by dynamic breakthrough experiments with high-purity ethylene (>99.99%) produced through a…

There has been emerging interest in the exploitation of the photophysical and photochemical properties of transition metal complexes for diagnostic and therapeutic applications. In this Perspective, we highlight the major recent advances in the development of luminescent and photofunctional transition metal complexes, in particular, those of rhenium(I), ruthenium(II), osmium(II), iridium(III), and platinum(II), as bioimaging reagents and phototherapeutic agents, with a focus on the molecular design strategies that harness and modulate the interesting photophysical and photochemical behavior of the complexes. We also discuss the current challenges and future outlook of transition metal complexes for both fundamental research and clinical applications.

Mitigating nitrogen oxide (NO x ) emissions is critical to tackle global warming and improve air quality. Conventional NO x abatement technologies for emission control suffer from a low efficiency at near ambient temperatures. Herein, we show an electrochemical pathway to reduce gaseous NO x that can be conducted at high reaction rates (400 mA cm –2 ) under ambient conditions. Various transition metals are evaluated for electrochemical reduction of NO and N 2 O to reveal the role of electrocatalyst in determining the product selectivity. Specifically, Cu is highly selective toward NH 3 formation with >80% Faradaic efficiency in NO electroreduction. Furthermore, the partial pressure study of NO electroreduction revealed that a high NO coverage facilitates the N–N coupling reaction. In acidic electrolytes, the formation of NH 3 is greatly favored, whereas the N 2 production is suppressed. Additional mechanistic studies were conducted by using flow electrochemical mass spectrometry to gain further insights into reaction pathways. This work provides a promising avenue toward abating…

Proton-coupled electron transfer (PCET) underpins energy conversion in chemistry and biology. Four energy systems are described whose discoveries are based on PCET: the water splitting chemistry of the Artificial Leaf, the carbon fixation chemistry of the Bionic Leaf-C, the nitrogen fixation chemistry of the Bionic Leaf-N and the Coordination Chemistry Flow Battery (CCFB). Whereas the Artificial Leaf, Bionic Leaf-C, and Bionic Leaf-N require strong coupling between electron and proton to reduce energetic barriers to enable high energy efficiencies, the CCFB requires complete decoupling of the electron and proton so as to avoid parasitic energy-wasting reactions. The proper design of PCET in these systems facilitates their implementation in the areas of (i) centralized large scale grid storage of electricity and (ii) decentralized energy storage/conversion using only sunlight, air and any water source to produce fuel and food within a sustainable cycle for the biogenic elements of C, N and P.

Recycling spent lithium-ion batteries (LIBs) is promising for resource reuse and environmental conservation but suffers from complex processing and loss of embedded value of spent LIBs in conventional metallurgy-based recycling routes. Herein, we selected a eutectic LiI–LiOH salt with the lowest eutectic point among binary eutectic lithium salt systems to provide a Li-rich molten environment, not only offering excess lithium but benefiting ion diffusion compared with that in the solid environment. Hence, the highly degraded LiNi 0.5 Co 0.2 Mn 0.3 O 2 in spent LIBs which suffers high Li-deficiency and serious structural defects with harmful phase transitions is directly regenerated. A facile one-step heating strategy in the presence of a combination of the eutectic lithium salt and Co 2 O 3 and MnO 2 additives not only simplifies the recycling process but also endows the cathode materials with lithium supplementation and structural ordering, which contributes to a restoration of the capacity and stable cycling performance. In particular, this eutectic salt with a low eutectic point…

Long-lived organic room-temperature phosphorescence (RTP) has sparked intense explorations, owing to the outstanding optical performance and exceptional applications. Because triplet excitons in organic RTP experience multifarious relaxation processes resulting from their high sensitivity, spin multiplicity, inevitable nonradiative decay, and external quenchers, boosting RTP performance by the modulated triplet-exciton behavior is challenging. Herein, we report that cross-linked polyphosphazene nanospheres can effectively promote long-lived organic RTP. Through molecular engineering, multiple carbonyl groups (C═O), heteroatoms (N and P), and heavy atoms (Cl) are introduced into the polyphosphazene nanospheres, largely strengthening the spin–orbit coupling constant by recalibrating the electronic configurations between singlet (S n ) and triplet (T n ) excitons. In order to further suppress nonradiative decay and avoid quenching under ambient conditions, polyphosphazene nanospheres are encapsulated with poly(vinyl alcohol) matrix, thus synchronously prompting phosphorescence lifetime…

Despite the clinical success of photodynamic therapy (PDT), the application of this medical technique is intrinsically limited by the low oxygen concentrations found in cancer tumors, hampering the production of therapeutically necessary singlet oxygen ( 1 O 2 ). To overcome this limitation, we report on a novel mitochondria-localized iridium(III) endoperoxide prodrug ( 2-O-IrAn ), which, upon two-photon irradiation in NIR, synergistically releases a highly cytotoxic iridium(III) complex ( 2-IrAn ), singlet oxygen, and an alkoxy radical. 2-O-IrAn was found to be highly (photo-)toxic in hypoxic tumor cells and multicellular tumor spheroids (MCTS) in the nanomolar range. To provide cancer selectivity and improve the pharmacological properties of 2-O-IrAn, it was encapsulated into a biotin-functionalized polymer. The generated nanoparticles were found to nearly fully eradicate the tumor inside a mouse model within a single treatment. This study presents, to the best of our knowledge, the first example of an iridium(III)-based endoperoxide prodrug for synergistic photodynamic…

Although the mass production of synthetic plastics has transformed human lives, it has resulted in waste accumulation on the earth. Here, we report a low-temperature conversion of polyethylene into olefins. By mixing the polyethylene feed with rationally designed ZSM-5 zeolite nanosheets at 280 °C in flowing hydrogen as a carrier gas, light hydrocarbons (C 1 -C 7 ) were produced with a yield of up to 74.6%, where 83.9% of these products were C 3 -C 6 olefins with almost undetectable coke formation. The reaction proceeds in multiple steps, including polyethylene melting, flowing to access the zeolite surface, cracking on the zeolite surface, formation of intermediates to diffuse into the zeolite micropores, and cracking into small molecules in the zeolite micropores. The ZSM-5 zeolite nanosheets kinetically matched the cascade cracking steps on the zeolite external surface and within micropores by boosting the intermediate diffusion. This feature efficiently suppressed the intermediate accumulation on the zeolite surface to minimize coke formation. In addition, we found that hydrogen…

Since its inception, atom transfer radical polymerization (ATRP) has seen continuous evolution in terms of the design of the catalyst and reaction conditions; today, it is one of the most useful techniques to prepare well-defined polymers as well as one of the most notable examples of catalysis in polymer chemistry. This Perspective highlights fundamental advances in the design of ATRP reactions and catalysts, focusing on the crucial role that mechanistic studies play in understanding, rationalizing, and predicting polymerization outcomes. A critical summary of traditional ATRP systems is provided first; we then focus on the most recent developments to improve catalyst selectivity, control polymerizations via external stimuli, and employ new photochemical or dual catalytic systems with an outlook to future research directions and open challenges.

The well-known limitation of alkaline fuel cells is the slack kinetics of the cathodic half-cell reaction, the oxygen reduction reaction (ORR). Platinum, being the most active ORR catalyst, is still facing challenges due to its corrosive nature and sluggish kinetics. Many novel approaches for substituting Pt have been reported, which suffer from stability issues even after mighty modifications. Designing an extremely stable, but unexplored ordered intermetallic structure, Pd 2 Ge, and tuning the electronic environment of the active sites by site-selective Pt substitution to overcome the hurdle of alkaline ORR is the main motive of this paper. The substitution of platinum atoms at a specific Pd position leads to Pt 0.2 Pd 1.8 Ge demonstrating a half-wave potential ( E 1/2 ) of 0.95 V vs RHE, which outperforms the state-of-the-art catalyst 20% Pt/C. The mass activity (MA) of Pt 0.2 Pd 1.8 Ge is 320 mA/mg Pt, which is almost 3.2 times better than that of Pt/C. E 1/2 and MA remained unaltered even after 50,000 accelerated degradation test (ADT) cycles, which makes it a promising stable…

Photocatalytic conversion of methane to value-added products under mild conditions, which represents a long sought-after goal for industrial sustainable production, remains extremely challenging to afford high production and selectivity using cheap catalysts. Herein, we present the crystal phase engineering of commercially available anatase TiO 2 via simple thermal annealing to optimize the structure–property correlation. A biphase catalyst with anatase (90%) and rutile (10%) TiO 2 with the optimal phase interface concentration exhibits exceptional performance in the oxidation of methane to formaldehyde under the reaction conditions of water solvent, oxygen atmosphere, and full-spectrum light irradiation. An unprecedented production of 24.27 mmol g cat –1 with an excellent selectivity of 97.4% toward formaldehyde is acquired at room temperature after a 3 h reaction. Both experimental results and theoretical calculations disclose that the crystal phase engineering of TiO 2 lengthens the lifetime of photogenerated carriers and favors the formation of intermediate methanol species,…

The theoretical capacity of a given electrode material is ultimately determined by the number of electrons transferred in each redox center. The design of multi-electron transfer processes could break through the limitation of one-electron transfer and multiply the total capacity but is difficult to achieve because multiple electron transfer processes are generally thermodynamically and kinetically more complex. Here, we report the discovery of two-electron transfer in monolayer Ni(OH) 2 nanosheets, which contrasts with the traditional one-electron transfer found in multilayer materials. First-principles calculations predict that the first oxidation process Ni 2+ → Ni 3+ occurs easily, whereas the second electron transfer in Ni 3+ → Ni 4+ is strongly hindered in multilayer materials by both the interlayer hydrogen bonds and the domain H structure induced by the Jahn–Teller distortion of the Ni 3+ (t 2g 6 e g 1 )-centered octahedra. In contrast, the second electron transfer can easily occur in monolayers because all H atoms are fully exposed. Experimentally, the as-prepared monolayer…

Covalent organic frameworks (COFs) are promising hosts in heterogeneous catalysis. Herein, we report a dual metalation strategy in a single two-dimensional-COF TpBpy for performing a variety of C–N cross-coupling reactions. [Ir(ppy) 2 (CH 3 CN) 2 ]PF 6 [ppy = 2-phenylpyridine], containing two labile CH 3 CN groups, and NiCl 2 are used as iridium and nickel-metal precursors, respectively, for postsynthetic decoration of the TpBpy COF. Moving from the traditional approach, we focus on the COF-backbone host for visible-light-mediated nickel-catalyzed C–N coupling reactions. The controlled metalation and recyclability without deactivation of both catalytic centers are unique with respect to previously reported coupling strategies. We performed various photoluminescence, electrochemical, kinetic, and Hammett correlation studies to understand the salient features of the catalyst and reaction mechanism. Furthermore, theoretical calculations delineated the feasibility of electron transfer from the Ir center to the Ni center inside the confined pore of the TpBpy COF. The dual metal anchoring…

The reaction of 5,5′-([2,2′-bipyridine]-5,5′-diyl)diisophthalaldehyde (BPDDP) with cyclohexanediamine and [benzidine (BZ)/[2,2′-bipyridine]-5,5′-diamine (BPDA)], respectively, affords a nitrogen-rich porous organic cage BPPOC and two two-dimensional (2D) covalent organic frameworks (COFs), USTB-1 and USTB-2 (USTB = University of Science and Technology Beijing), under suitable conditions. Interestingly, BPPOC with a single-crystal X-ray diffraction structure is able to successfully transform into USTB-1 and USTB-2 (newly converted COFs denoted as USTB-1c and USTB-2c, respectively) upon exchange of the imine unit of cyclohexanediamine in the cage by BZ and BPDA. Such a transformation also enables the isolation of analogous COFs (USTB-3c and USTB-4c) on the basis of an isostructural organic cage, BTPOC, which is derived from 5,5′-([2,2′-bithiophene]-4,4′-diyl)diisophthalaldehyde (BTDDP) and cyclohexanediamine. However, the conventional solvothermal reaction between BTDDP and BPDA leads to an impure phase of USTB-4 containing incompletely converted aldehyde groups due to the limited…

Ultrapure N 2 gas was bubbled through water, and the humidified output containing undetectable concentrations of ozone filled a closed chamber in which 18 MΩ-cm water was sprayed through a silica capillary to form microdroplets. Analysis of the collected microdroplets by NMR spectroscopy showed the presence of hydrogen peroxide at a concentration level ranging from 0.3 to 1.5 μM depending on the flow conditions. This was confirmed using a spectrofluorometric assay. We suggest that this finding establishes that when sprayed to form microdroplets, water has the ability to produce hydrogen peroxide by itself. When the N 2 gas is replaced by compressed air or O 2 gas, the concentration of hydrogen peroxide is found to increase, indicating that gas–surface interactions with O 2 in aqueous microdroplets promote the formation of hydrogen peroxide.

Although polyethylene (PE) and polypropylene (PP) are by far the world's largest volume plastics, only a tiny fraction of these energy-rich polyolefins are currently recycled. Depolymerization of PE to its constituent monomer, ethylene, is highly endothermic and conventionally accessible only through unselective, high-temperature pyrolysis. Here, we provide experimental demonstrations of our recently proposed tandem catalysis strategy, which uses ethylene to convert PE to propylene, the commodity monomer used to make PP. The approach combines rapid olefin metathesis with rate-limiting isomerization. Monounsaturated PE is progressively disassembled at modest temperatures via many consecutive ethenolysis events, resulting selectively in propylene. Fully saturated PE can be converted to unsaturated PE starting with a single transfer dehydrogenation to ethylene, which produces a small amount of ethane (1 equiv per dehydrogenation event). These principles are demonstrated using both homogeneous and heterogeneous catalysts. While selectivity under batch conditions is limited at high…

High Resolution Image Download MS PowerPoint Slide Plasma catalysis is a promising technology for decentralized small-scale ammonia (NH 3 ) synthesis under mild conditions using renewable energy, and it shows great potential as an alternative to the conventional Haber–Bosch process. To date, this emerging process still suffers from a low NH 3 yield due to a lack of knowledge in the design of highly efficient catalysts and the in situ plasma-induced reverse reaction (i.e., NH 3 decomposition). Here, we demonstrate that a bespoke design of supported Ni catalysts using mesoporous MCM-41 could enable efficient plasma-catalytic NH 3 production at 35 °C and 1 bar with >5% NH 3 yield at 60 kJ/L. Specifically, the Ni active sites were deliberately deposited on the external surface of MCM-41 to enhance plasma–catalyst interactions and thus NH 3 production. The desorbed NH 3 could then diffuse into the ordered mesopores of MCM-41 to be shielded from decomposition due to the absence of plasma discharge in the mesopores of MCM-41, that is, “shielding protection”, thus driving the reaction…

The atomically dispersed metal catalyst or single-atom catalyst (SAC) with the utmost metal utilization efficiency shows excellent selectivity toward ethylene compared to the metal nanoparticles catalyst in the acetylene semi-hydrogenation reaction. However, these catalysts normally work at relatively high temperatures. Achieving low-temperature reactivity while preserving high selectivity remains a challenge. To improve the intrinsic reactivity of SACs, rationally tailoring the coordination environments of the first metal atom by coordinating it with a second neighboring metal atom affords an opportunity. Here, we report the fabrication of a dual-atom catalyst (DAC) that features a bonded Pd 1 –Cu 1 atomic pair anchoring on nanodiamond graphene (ND@G). Compared to the single-atom Pd or Cu catalyst, it exhibits increased reactivity at a lower temperature, with 100% acetylene conversion and 92% ethylene selectivity at 110 °C. This work provides a strategy for designing DACs for low-temperature hydrogenation by manipulating the coordination environment of catalytic sites at the atomic…

Luminol-based electrochemiluminescence (ECL) can be readily excited by various reactive oxygen species (ROS) electrogenerated with an oxygen reduction reaction (ORR). However, the multiple active intermediates involved in the ORR catalyzed with complex nanomaterials lead to recognizing the role of ROS still elusive. Moreover, suffering from the absence of the direct electrochemical oxidation of luminol at the cathode and poor transformation efficiency of O 2 to ROS, the weak cathodic ECL emission of luminol is often neglected. Herein, owing to the tunable coordination environment and structure-dependent catalytic feature, single-atom catalysts (SACs) are employed to uncover the relationship between the intrinsic ORR activity and ECL behavior. Interestingly, the traditionally negligible cathodic ECL of luminol is first boosted (ca. 70-fold) owing to the combination of electrochemical ORR catalyzed via SACs and chemical oxidation of luminol. The boosted cathodic ECL emission exhibits electron-transfer pathway-dependent response by adjusting the surrounding environment of the center…

This study demonstrates a special ultrathin N-doped graphene nanomesh (NGM) as a robust scaffold for highly exposed Fe–N 4 active sites. Significantly, the pore sizes of the NGM can be elaborately regulated by adjusting the thermal exfoliation conditions to simultaneously disperse and anchor Fe–N 4 moieties, ultimately leading to highly loaded Fe single-atom catalysts (SA-Fe-NGM) and a highly exposed morphology. The SA-Fe-NGM is found to deliver a superior oxygen reduction reaction (ORR) activity in acidic media (half-wave potential = 0.83 V vs RHE) and a high power density of 634 mW cm –2 in the H 2 /O 2 fuel cell test. First-principles calculations further elucidate the possible catalytic mechanism for ORR based on the identified Fe–N 4 active sites and the pore size distribution analysis. This work provides a novel strategy for constructing highly exposed transition metals and nitrogen co-doped carbon materials (M–N–C) catalysts for extended electrocatalytic and energy storage applications.

The development of smart and sustainable photocatalysts is in high priority for the synthesis of H 2 O 2 because the global demand for H 2 O 2 is sharply rising. Currently, the global market share for H 2 O 2 is around 4 billion US$ and is expected to grow by about 5.2 billion US$ by 2026. Traditional synthesis of H 2 O 2 via the anthraquinone method is associated with the generation of substantial chemical waste as well as the requirement of a high energy input. In this respect, the oxidative transformation of pure water is a sustainable solution to meet the global demand. In fact, several photocatalysts have been developed to achieve this chemistry. However, 97% of the water on our planet is seawater, and it contains 3.0–5.0% of salts. The presence of salts in water deactivates the existing photocatalysts, and therefore, the existing photocatalysts have rarely shown reactivity toward seawater. Considering this, a sustainable heterogeneous photocatalyst, derived from hydrolysis lignin, has been developed, showing an excellent reactivity toward generating H 2 O 2 directly from…

High Resolution Image Download MS PowerPoint Slide Electrochemically active covalent organic frameworks (COFs) are promising electrode materials for Li-ion batteries. However, improving the specific capacities of COF-based electrodes requires materials with increased conductivity and a higher concentration of redox-active groups. Here, we designed a series of pyrene-4,5,9,10-tetraone COF (PT-COF) and carbon nanotube (CNT) composites (denoted as PT-COFX, where X = 10, 30, and 50 wt % of CNT) to address these challenges. Among the composites, PT-COF50 achieved a capacity of up to 280 mAh g –1 as normalized to the active COF material at a current density of 200 mA g –1, which is the highest capacity reported for a COF-based composite cathode electrode to date. Furthermore, PT-COF50 exhibited excellent rate performance, delivering a capacity of 229 mAh g –1 at 5000 mA g –1 (18.5C). Using operando Raman microscopy the reversible transformation of the redox-active carbonyl groups of PT-COF was determined, which rationalizes an overall 4 e – /4 Li + redox process per…

The development of rechargeable Na–S batteries is very promising, thanks to their considerably high energy density, abundance of elements, and low costs and yet faces the issues of sluggish redox kinetics of S species and the polysulfide shuttle effect as well as Na dendrite growth. Following the theory-guided prediction, the rare-earth metal yttrium (Y)–N 4 unit has been screened as a favorable Janus site for the chemical affinity of polysulfides and their electrocatalytic conversion, as well as reversible uniform Na deposition. To this end, we adopt a metal–organic framework (MOF) to prepare a single-atom hybrid with Y single atoms being incorporated into the nitrogen-doped rhombododecahedron carbon host (Y SAs/NC), which features favorable Janus properties of sodiophilicity and sulfiphilicity and thus presents highly desired electrochemical performance when used as a host of the sodium anode and the sulfur cathode of a Na–S full cell. Impressively, the Na–S full cell is capable of delivering a high capacity of 822 mAh g –1 and shows superdurable cyclability (97.5% capacity…

CO 2 electroreduction to high-energy-density C 2+ products is highly attractive, whereas the C 2+ selectivity under industrial current densities is still unsatisfying. Here, an anti-swelling anion exchange ionomer (AEI) was first proposed to optimize the local environment for promoting industrial-current-density CO 2 -to-C 2+ electroreduction. Taking the anti-swelling AEI-modified oxide-derived Cu nanosheets as an example, in situ Raman spectroscopy and contact angle measurements revealed that the OH – -accumulated -N(CH 3 ) 3 + groups and anti-swelling backbone of AEI could synergistically regulate the local pH level and water content. In situ Fourier-transform infrared spectroscopy and theoretical calculations demonstrated that the higher local pH value could lower the energy barrier for the rate-limiting COCO* hydrogenated to COCOH* from 0.08 to 0.04 eV, thereby boosting the generation of C 2+ products. Owing to the anti-swelling backbone, the optimized water content of 3.5% could suppress the competing H 2 evolution and hence facilitate the proton-electron transfer step for C 2+…

Solution processable flexible transparent electrodes (FTEs) are urgently needed to boost the efficiency and mechanical stability of flexible organic solar cells (OSCs) on a large scale. However, how to balance the optoelectronic properties and meanwhile achieve robust mechanical behavior of FTEs is still a huge challenge. Silver nanowire (AgNW) electrodes, exhibiting easily tuned optoelectronic/mechanical properties, are attracting considerable attention, but their poor contacts at the junction site of the AgNWs increase the sheet resistance and reduce mechanical stability. In this study, an ionic liquid (IL)-type reducing agent containing Cl – and a dihydroxyl group was employed to control the reduction process of silver (Ag) in AgNW-based FTEs precisely. The Cl – in the IL regulates the Ag + concentration through the formation and dissolution of AgCl, whereas the dihydroxyl group slowly reduces the released Ag + to form metal Ag. The reduced Ag grew in situ at the junction site of the AgNWs in a twin-crystal growth mode, facilitating an atomic-level contact between the AgNWs and…

Volatile solid additives (SADs) are considered as a simple yet effective approach to tune the film morphology for high-performance organic solar cells (OSCs). However, the structural effects of the SADs on the photovoltaic performance are still elusive. Herein, two volatilizable SADs were designed and synthesized. One is SAD1 with twisted conformation, while the other one is planar SAD2 with the S···O noncovalent intramolecular interactions (NIIs). The theoretical and experimental results revealed that the planar SAD2 with smaller space occupation can more easily insert between the Y6 molecules, which is beneficial to form a tighter intermolecular packing mode of Y6 after thermal treatment. As a result, the SAD2-treated OSCs exhibited less recombination loss, more balanced charge mobility, higher hole transfer rate, and more favorable morphology, resulting in a record power conversion efficiency (PCE) of 18.85% (certified PCE: 18.7%) for single-junction binary OSCs. The universality of this study shed light on understanding the conformation effects of SADs on photovoltaic…

Drugs targeting SARS-CoV-2 could have saved millions of lives during the COVID-19 pandemic, and it is now crucial to develop inhibitors of coronavirus replication in preparation for future outbreaks. We explored two virtual screening strategies to find inhibitors of the SARS-CoV-2 main protease in ultralarge chemical libraries. First, structure-based docking was used to screen a diverse library of 235 million virtual compounds against the active site. One hundred top-ranked compounds were tested in binding and enzymatic assays. Second, a fragment discovered by crystallographic screening was optimized guided by docking of millions of elaborated molecules and experimental testing of 93 compounds. Three inhibitors were identified in the first library screen, and five of the selected fragment elaborations showed inhibitory effects. Crystal structures of target-inhibitor complexes confirmed docking predictions and guided hit-to-lead optimization, resulting in a noncovalent main protease inhibitor with nanomolar affinity, a promising in vitro pharmacokinetic profile, and broad-spectrum…

Considering that hypoxia is closely associated with tumor proliferation, invasion, metastasis, and drug resistance, it is of great significance to overcome hypoxia in tumor treatment. Herein, we report a hypoxia-induced specific photothermal therapy (PTT) based on the photothermal agent of supramolecular perylene diimide radical anions. Hypoxic regions in various tumors display strong reductive ability, and in such environments the supramolecular complex of a perylene diimide derivative and cucurbit[7]uril could be reduced to supramolecular perylene diimide radical anions. Benefiting from the strong NIR absorption and good photothermal conversion performance of the in situ generated supramolecular perylene diimide radical anions, the hypoxia-induced PTT strategy exhibits excellent photothermal therapeutic efficiency as well as good specificity and biological safety. Moreover, hypoxia inducible factor expression of tumors decreases to the normal level after PTT treatment. It is anticipated that such a hypoxia-induced specific PTT strategy opens new horizons for photothermal therapy…

Amide-linked covalent organic frameworks (amide COFs) possess enormous potentials in practical applications benefiting from their high stability and polyamide structures. However, they suffer from very limited accessibility. Herein, we report a new linkage conversion method to rapidly synthesize crystalline amide COFs through oxidation of imine linkages in their corresponding imine-linked frameworks with KHSO 5 as an oxidant under very mild conditions. This synthetic strategy is general, facile, efficient, and scalable, as demonstrated by the procedure of simply stirring mixtures of imine-linked COFs (seven examples) and KHSO 5 in anhydrous dimethylformamide for several hours to complete the conversions and gram-scale synthesis. The high efficiency of this approach enables facile production of amide COFs from widely available imine-linked COFs, which lays the foundation for exploring practical applications of this unique type of polyamide material.

Facing the increasingly serious energy and environmental crisis, the development of heteronuclear metal-free double-atom catalysts is a potential strategy to realize efficient catalytic nitrogen reduction with low energy consumption and no pollution because it could combine the advantages of flexible active sites in double-atom catalysts while also being pollution-free and have high Faraday efficiency in metal-free catalysts simultaneously. However, according to the existing mechanism, the finite orbits of other nonmetallic atoms, except the boron atom, reduce the possibility of metal-free catalysis and hinder the development of heteronuclear metal-free double-atom catalysts. Herein, we propose a new "capture-backdonation-recapture" mechanism, which skillfully uses the electron capture-backdonation-recapture between boron, the substrate, and other nonmetallic elements to solve the above problems. Based on this mechanism, by means of the first-principle calculations, the material structure, adsorption energy, catalytic activity, and selectivity of 36 catalysts are systematically…

Noble metals have an irreplaceable role in catalyzing electrochemical reactions. However, large overpotential and poor long-term stability still prohibit their usage in many reactions (e.g., oxygen evolution/reduction). With regard to the low natural abundance, the improvement of their overall electrocatalytic performance (activity, selectivity, and stability) was urgently necessary. Herein, strong metal–support interaction (SMSI) was modulated through an unprecedented time-dependent mechanical milling method on Pd-loaded oxygenated TiC electrocatalysts. The encapsulation of Pd surfaces with reduced TiO 2– x overlayers is precisely controlled by the mechanical milling time. This encapsulation induced a valence band restructuring and lowered the d-band center of surface Pd atoms. For hydrogen peroxide electrosynthesis through the two-electron oxygen reduction reaction (ORR), these electronic and geometric modifications resulted in optimal adsorption energies of reaction intermediates. Thus, SMSI phenomena not only enhanced electrocatalytic activity and selectivity but also created an…

The ability to reverse controlled radical polymerization and regenerate the monomer would be highly beneficial for both fundamental research and applications, yet this has remained very challenging to achieve. Herein, we report a near-quantitative (up to 92%) and catalyst-free depolymerization of various linear, bulky, cross-linked, and functional polymethacrylates made by reversible addition-fragmentation chain-transfer (RAFT) polymerization. Key to our approach is to exploit the high end-group fidelity of RAFT polymers to generate chain-end radicals at 120 °C. These radicals trigger a rapid unzipping of both conventional (e.g., poly(methyl methacrylate)) and bulky (e.g., poly(oligo(ethylene glycol) methyl ether methacrylate)) polymers. Importantly, the depolymerization product can be utilized to either reconstruct the linear polymer or create an entirely new insoluble gel that can also be subjected to depolymerization. This work expands the potential of polymers made by controlled radical polymerization, pushes the boundaries of depolymerization, offers intriguing mechanistic…

The development of synthetic strategies for the preparation of bioisosteric compounds is a demanding undertaking in medicinal chemistry. Numerous strategies have been developed for the synthesis of bicyclo[1.1.1]pentanes (BCPs), bridge-substituted BCPs, and bicyclo[2.1.1]hexanes. However, progress on the synthesis of bicyclo[3.1.1]heptanes, which serve as meta-substituted arene bioisosteres, has not been previously explored. Herein, we disclose the first photoinduced [3σ + 2σ] cycloaddition for the synthesis of trisubstituted bicyclo[3.1.1]heptanes using bicyclo[1.1.0]butanes and cyclopropylamines. This transformation not only uses mild and operationally simple conditions but also provides unique meta-substituted arene bioisosteres. The applicability of this method is showcased by simple derivatization reactions.

High Resolution Image Download MS PowerPoint Slide Metal oxides and oxyhydroxides exhibit state-of-the-art activity for the oxygen evolution reaction (OER); however, their reaction mechanism, particularly the relationship between charging of the oxide and OER kinetics, remains elusive. Here, we investigate a series of Mn-, Co-, Fe-, and Zn-doped nickel oxides using operando UV–vis spectroscopy coupled with time-resolved stepped potential spectroelectrochemistry. The Ni 2+ /Ni 3+ redox peak potential is found to shift anodically from Mn- < Co- < Fe- < Zn-doped samples, suggesting a decrease in oxygen binding energetics from Mn- to Zn-doped samples. At OER-relevant potentials, using optical absorption spectroscopy, we quantitatively detect the subsequent oxidation of these redox centers. The OER kinetics was found to have a second-order dependence on the density of these oxidized species, suggesting a chemical rate-determining step involving coupling of two oxo species. The intrinsic turnover frequency per oxidized species exhibits a volcano trend with the binding energy of oxygen on…

The catalytic activity of transition metal-based catalysts is overwhelmingly dependent on the geometric configuration. Identification and interpretation of different geometric configurations’ contributions to catalytic activity plays a pivotal role in catalytic performance elevation. Spinel structured AB 2 X 4, consisting of tetrahedral (A 2+ –X) T d and octahedral (B 3+ –X) O h geometric configurations, is a prototypical category of multi-geometric-configuration featured catalysts. However, it is still under debate about the predominant geometric configuration responsible for spinel catalyst activity, and the mechanistic origin of specific activity discrepancy among varied geometric configurations also remains ambiguous. Herein, Co T d 2+ and Co O h 3+ in Co 3 O 4 are replaced by catalytically inert Zn 2+ and Al 3+ to yield ZnCo 2 O 4 and CoAl 2 O 4, respectively, thus ensuring the manipulable exposure of monotypic active configurations. By means of pulse voltammetry and in situ extended X-ray absorption fine structure, (Co 3+ –O) O h is identified to be dominant for alkaline HER.…

Embedding metal species into zeolite frameworks can create framework-bond metal sites in a confined microenvironment. The metals sitting in the specific T sites of zeolites and their crystalline surroundings are both committed to the interaction with the reactant, participation in the activation, and transient state achievement during the whole catalytic process. Herein, we construct isolated Co-motifs into purely siliceous MFI zeolite frameworks (Co-MFI) and reveal the location and microenvironment of the isolated Co active center in the MFI zeolite framework particularly beneficial for propane dehydrogenation (PDH). The isolated Co-motif with the distorted tetrahedral structure ({(≡SiO) 2 Co(HO–Si≡) 2 }, two Co–O–Si bonds, and two pseudobridging hydroxyls (Co···OH–Si) is located at T 1(7) and T 3(9) sites of the MFI zeolite. DFT calculations and deuterium-labeling reactions verify that the isolated Co-motif together with the MFI microenvironment collectively promotes the PDH reaction by providing an exclusive microenvironment to preactivate C 3 H 8, polarizing the oxygen in…

A new kind of piperazine-linked covalent organic framework (COF) was synthesized through the nucleophilic substitution reaction between octaminophthalocyanines and hexadecafluorophthalocyanines. The two-dimensional (2D) frameworks are in tetragonally shaped polygon sheets, which stack in an AA stacking mode to constitute periodically ordered metallophthalocyanine columns and one-dimensional (1D) microporous channels. The piperazine-linked COFs exhibit excellent chemical stability and permanent porosity. By virtue of the neatly arrayed phthalocyanine columns and inbuilt cationic radicals, the piperazine-linked frameworks are highly conductive. The conductivity values of NiPc-NH-CoPcF 8 COF reached up to 2.72 and 12.7 S m –1 for pellet and film samples, respectively. Moreover, this p -type conductive COF exhibited a high carrier mobility of 35.4 cm 2 V –1 s –1 . Both the electric conductivity and carrier mobility set new records for conductive COFs.

Alcohols and carboxylic acids are among the most commercially abundant, synthetically versatile, and operationally convenient functional groups in organic chemistry. Under visible light photoredox catalysis, these native synthetic handles readily undergo radical activation, and the resulting open-shell intermediates can subsequently participate in transition metal catalysis. In this report, we describe the C( sp 3 )–C( sp 3 ) cross-coupling of alcohols and carboxylic acids through the dual combination of N -heterocyclic carbene (NHC)-mediated deoxygenation and hypervalent iodine-mediated decarboxylation. This mild and practical Ni-catalyzed radical-coupling protocol was employed to prepare a wide array of alkyl–alkyl cross-coupled products, including highly congested quaternary carbon centers from the corresponding tertiary alcohols or tertiary carboxylic acids. We demonstrate the synthetic applications of this methodology to alcohol C 1 -alkylation and formal homologation, as well as to the late-stage functionalization of drugs, natural products, and biomolecules.

The carbon–carbon (C–C) bond formation is essential for the electroconversion of CO 2 into high-energy-density C 2+ products, and the precise coupling pathways remain controversial. Although recent computational investigations have proposed that the OC–COH coupling pathway is more favorable in specific reaction conditions than the well-known CO dimerization pathway, the experimental evidence is still lacking, partly due to the separated catalyst design and mechanistic/spectroscopic exploration. Here, we employ density functional theory calculations to show that on low-coordinated copper sites, the *CO bindings are strengthened, and the adsorbed *CO coupling with their hydrogenation species, *COH, receives precedence over CO dimerization. Experimentally, we construct a fragmented Cu catalyst with abundant low-coordinated sites, exhibiting a 77.8% Faradaic efficiency for C 2+ products at 300 mA cm –2 . With a suite of in situ spectroscopic studies, we capture an *OCCOH intermediate on the fragmented Cu surfaces, providing direct evidence to support the OC–COH coupling pathway. The…

Development of water-stable metal–organic frameworks (MOFs) for promising visible-light-driven photocatalytic water splitting is highly desirable but still challenging. Here we report a novel p-type nickel-based MOF single crystal (Ni-TBAPy-SC) and its exfoliated nanobelts (Ni-TBAPy-NB) that can bear a wide range of pH environment in aqueous solution. Both experimental and theoretical results indicate a feasible electron transfer from the H 4 TBAPy ligand (light-harvesting center) to the Ni–O cluster node (catalytic center), on which water splitting to produce hydrogen can be efficiently driven free of cocatalyst. Compared to the single crystal, the exfoliated two-dimensional (2D) nanobelts show more efficient charge separation due to its shortened charge transfer distance and remarkably enhanced active surface areas, resulting in 164 times of promoted water reduction activity. The optimal H 2 evolution rate on the nanobelt reaches 98 μmol h –1 (ca. 5 mmol h –1 g –1 ) showing benchmarked apparent quantum efficiency (AQE) of 8.0% at 420 nm among water-stable MOFs photocatalysts.