The 100 most-cited articles in Advanced Functional Materials, 2020

Abstract The development of low‐cost, high‐efficiency, and robust electrocatalysts for the oxygen evolution reaction (OER) is urgently needed to address the energy crisis. In recent years, non‐noble‐metal‐based OER electrocatalysts have attracted tremendous research attention. Beginning with the introduction of some evaluation criteria for the OER, the current OER electrocatalysts are reviewed, with the classification of metals/alloys, oxides, hydroxides, chalcogenides, phosphides, phosphates/borates, and other compounds, along with their advantages and shortcomings. The current knowledge of the reaction mechanisms and practical applications of the OER is also summarized for developing more efficient OER electrocatalysts. Finally, the current states, challenges, and some perspectives for non‐noble‐metal‐based OER electrocatalysts are discussed.

Abstract Since the first report on electromagnetic interference (EMI) shielding of 2D Ti 3 C 2 T x in 2016, MXenes have captured the leadership position among lightweight shielding materials due to many advantages, including their excellent shielding performance, outstanding metallic conductivity, low density, large specific surface area, tunable surface chemistry, and solution processability. MXenes triggered a huge interest in the materials research community, leading to over 100 reported publications on MXenes' EMI shielding within 3 years. Many MXenes composites and hybrids in different structural forms, such as compact and laminate structures, layer‐by‐layer assemblies, porous foams and aerogels, and segregated structures, have been explored to further improve the intrinsic EMI shielding properties of MXenes. This article comprehensively reviews the recent advancements in MXene‐based EMI shielding materials with different structural morphologies and provides an insight into future challenges and guidelines for finding material solutions for the next‐generation shielding…

Abstract Piezoelectric‐based catalysis that relies on the charge energy or separation efficiency of charge carriers has attracted significant attention. The piezo‐potential induced by strain or stress can induce a giant electric field, which has been demonstrated to be an effective means for charge energy shifting or transferring electrons and holes. In recent years, intense efforts have been made in this subject, and the research has mainly focussed on two aspects: i) Alteration of surface charge energy by piezo‐potential in piezocatalysis; ii) the separation of photo‐generated charge carriers and the catalytic activity enhancement of an integrated piezoelectric semiconductor or coupled system composed of piezoelectrics and semiconductors. Systematically summarizing the advances of the above two aspects is helpful in the context of deepening understanding of the relevant issues and developing new ideas for piezoelectric‐based catalysis. In this review, a comprehensive summary on piezocatalysis and piezo‐photocatalysis is provided. The charge transfer behaviors and catalytic…

Abstract Zn metal has been regarded as the most promising anode for aqueous batteries due to its high capacity, low cost, and environmental benignity. Zn anode still suffers, however, from low Coulombic efficiency due to the side reactions and dendrite growth in slightly acidic electrolytes. Here, the Zn plating/stripping mechanism is thoroughly investigated in 1 m ZnSO 4 electrolyte, demonstrating that the poor performance of Zn metal in mild electrolyte should be ascribed to the formation of a porous by‐product (Zn 4 SO 4 (OH) 6 · x H 2 O) layer and serious dendrite growth. To suppress the side reactions and dendrite growth, a highly viscoelastic polyvinyl butyral film, functioning as an artificial solid/electrolyte interphase (SEI), is homogeneously deposited on the Zn surface via a simple spin‐coating strategy. This dense artificial SEI film not only effectively blocks water from the Zn surface but also guides the uniform stripping/plating of Zn ions underneath the film due to its good adhesion, hydrophilicity, ionic conductivity, and mechanical strength. Consequently, this…

Abstract Demand for energy in day to day life is increasing exponentially. However, existing energy storage technologies like lithium ion batteries cannot stand alone to fulfill future needs. In this regard, potassium ion batteries (KIBs) that utilize K ions in their charge storage mechanism have attracted considerable attention due to their unique properties and are therefore established as one of the future battery systems of interest among the scientific community. Nevertheless, the development and identification of appropriate electrode materials is very essential for practical applications. This review features the current development in KIBs electrode and electrolyte materials, the present challenges facing this technology (in the commercial aspect), and future aspects to develop fully functional KIBs. The potassium storage mechanisms, evolution of the KIBs, and the advantages and disadvantages of each category of materials are included. Additionally, various approaches to enhance the electrochemical performances of KIBs are also discussed. This review is not only an…

Abstract To date, ionic conducting hydrogel attracts tremendous attention as an alternative to the conventional rigid metallic conductors in fabricating flexible devices, owing to their intrinsic characteristics. However, simultaneous realization of high stiffness, toughness, ionic conductivity, and freezing tolerance through a simple approach is still a challenge. Here, a novel highly stretchable (up to 660%), strong (up to 2.1 MPa), tough (5.25 MJ m −3 ), and transparent (up to 90%) ionic conductive (3.2 S m −1 ) organohydrogel is facilely fabricated, through sol–gel transition of polyvinyl alcohol and cellulose nanofibrils (CNFs) in dimethyl sulfoxide‐water solvent system. The ionic conductive organohydrogel presents superior freezing tolerance, remaining flexible and conductive (1.1 S m −1 ) even at −70 °C, as compared to the other reported anti‐freezing ionic conductive (organo)hydrogel. Notably, this material design demonstrates synergistic effect of CNFs in boosting both mechanical properties and ionic conductivity, tackling a long‐standing dilemma among strength, toughness,…

Abstract Developing physical double‐network (DN) removable hydrogel adhesives with both high healing efficiency and photothermal antibacterial activities to cope with multidrug‐resistant bacterial infection, wound closure, and wound healing remains an ongoing challenge. An injectable physical DN self‐healing hydrogel adhesive under physiological conditions is designed to treat multidrug‐resistant bacteria infection and full‐thickness skin incision/defect repair. The hydrogel adhesive consists of catechol–Fe 3+ coordination cross‐linked poly(glycerol sebacate)‐ co ‐poly(ethylene glycol)‐ g ‐catechol and quadruple hydrogen bonding cross‐linked ureido‐pyrimidinone modified gelatin. It possesses excellent anti‐oxidation, NIR/pH responsiveness, and shape adaptation. Additionally, the hydrogel presents rapid self‐healing, good tissue adhesion, degradability, photothermal antibacterial activity, and NIR irradiation and/or acidic solution washing‐assisted removability. In vivo experiments prove that the hydrogels have good hemostasis of skin trauma and high killing ratio for…

Abstract Aqueous Zn batteries have drawn tremendous attention for their several advantages. However, the challenges of Zn anodes such as the corrosion and ZnO densification have compromised their application in rechargeable Zn‐based batteries. In this paper, a straightforward strategy is employed to facilitate the uniform Zn stripping/plating of the Zn anode through using a ZrO 2 coating layer, which contributes to the controllable nucleation sites for Zn 2+ and fast Zn 2+ transportation through the favorable Maxwell–Wagner polarization. As a result, the low polarization (24 mV at 0.25 mA cm −2 ), high Coulombic efficiency (99.36% at 20 mA cm −2 ), and long cycle life (over 3800 h at 0.25 mA cm −2 ) can be obtained for the ZrO 2 ‐coated Zn anode. It is believed that the ZrO 2 coating layer can also act as an inert physical barrier to decrease the contact of the anode and electrolyte, thus reducing both the Zn corrosion and formation of ZnO densification, and then improve the reversibility of Zn anode. The results demonstrated in this work provide an appealing strategy for the future…

Abstract In comparison to traditional bulky and rigid electronic devices, the human–machine interaction (HMI) system with flexible and wearable components is an inevitable future trend. To achieve effective, intuitive, and seamless manipulation of high‐performance wearable HMI systems, it is important to develop effective strategies for designing material microstructures on flexible sensors and electric devices with excellent mechanical flexibility and stretchability. The real‐time acquisition of human physiology and surrounding signals through accurate and flexible sensors is the basis of wearable HMIs. Herein, the construction of a wearable HMI system that utilizes sensors, communication modes, and actuators is reviewed. The mechanisms and strategies for designing various flexible sensors based on different mechanisms are analyzed and discussed. The functional mechanism, material selection, and novel design strategies of each part are summarized in detail. The different communication modes in interactive systems and the manufacturing technology of soft machines are also…

Abstract Since the first report in 2015, multiresonant thermally activated delayed fluorescent (MR‐TADF) compounds, a subclass of TADF emitters based on a heteroatom‐doped nanographene material, have come to the fore as attractive hosts as well as emitters for organic light‐emitting diodes (OLEDs). MR‐TADF compounds typically show very narrow‐band emission, high photoluminescence quantum yields, and small Δ E ST values, typically around 200 meV, coupled with high chemical and thermal stabilities. These materials properties have translated into some of the best reported deep‐blue TADF OLEDs. Here, a detailed review of MR‐TADF compounds and their derivatives reported so far is presented. This review comprehensively documents all MR‐TADF compounds, with a focus on the synthesis, optoelectronic behavior, and OLED performance. In addition, computational approaches are surveyed to accurately model the excited state properties of these compounds.

Abstract Since their discovery in 2011, 2D transition metal carbide/nitride (MXene) materials have received extensive interest due to their unique planar structure, chemical diversity, and superior physiochemical features. Very recently, MXenes have demonstrated outstanding photothermal conversion by virtue of excellent electromagnetic wave absorption capacity and a localized surface plasmon resonance effect. Photothermal conversion is an efficient way to utilize solar energy that allows the transformation of solar illumination into thermal energy, thus enabling MXenes to be applied in various fields, such as solar steam generation and biomedicals. However, the light‐to‐heat capability of MXenes has been paid much less attention until now. Recent progress in photothermal MXenes is reviewed to provide a comprehensive understanding of their photothermal conversion mechanism and applications. First, synthetic strategies of MXenes and their nanocomposites will be briefly summarized, and the discussion of the photothermal conversion mechanism and, most importantly, current advances in…

Abstract Additive manufacturing (AM) is the process of printing 3D objects in a layer‐by‐layer manner. Polymers and their composites are some of the most widely used materials in modern industries and are of great interest in the field of AM due to their vast potential for various applications, especially in the medical, aerospace, and automotive industries. Many studies have been conducted to develop new polymer materials for AM techniques, which include vat photopolymerization, material jetting, powder bed fusion, material extrusion, binder jetting, and sheet lamination. Although several reviews on the development of polymer materials for AM have been published, most of them only focus on a specific application, process, or type of material. Therefore, this article serves to provide a comprehensive review on the progress in polymer material development for AM techniques. It begins with an introduction to different AM techniques, followed by highlighting the progress of their development. Material requirements, notable advances in newly developed materials and their potential…

Abstract The recent advances in electrocatalysis for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), hydrogen oxidation reaction (HOR), carbon dioxide reduction reaction (CO 2 RR), and nitrogen reduction reaction (NRR) are thoroughly reviewed. This comprehensive review focuses on the single‐atom catalysts (SACs) including Sc, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Sn, W, Bi, Ru, Rh, Pd, Ag, Ir, Pt, and Au with single‐metal sites or dual‐metal sites. The recent development of single‐atom electrocatalysts with novel configurations and compositions is documented. The understanding of the process–structure–property relationships is highlighted. For the SACs, their electrocatalytic performance and stability in fuel cells, zinc–air batteries, electrolyzers, CO 2 RR, and NRR are summarized. The challenges and perspectives in the emerging field of single‐atom electrocatalysis are discussed.

Abstract Microbial colonization on material surfaces is ubiquitous. Biofilms derived from surface‐colonized microbes pose serious problems to the society from both an economical perspective and a health concern. Incorporation of antimicrobial nanocompounds within or on the surface of materials, or by coatings, to prevent microbial adhesion or kill the microorganisms after their attachment to biofilms, represents an important strategy in an increasingly challenging field. Over the last decade, many studies have been devoted to preparing meta‐based nanomaterials that possess antibacterial, antiviral, and antifungal activities to combat pathogen‐related diseases. Herein, an overview on the state‐of‐the‐art antimicrobial nanosized metal‐based compounds is provided, including metal and metal oxide nanoparticles as well as transition metal nanosheets. The antimicrobial mechanism of these nanostructures and their biomedical applications such as catheters, implants, medical delivery systems, tissue engineering, and dentistry are discussed. Their properties as well as potential caveats such…

Abstract While nature has optimized its antifouling strategies over millions of years, synthetic antifouling coatings have not yet reached technological maturity. For an antifouling coating to become technically feasible, it should fulfill many requirements: high effectiveness, long‐term stability, durability, ecofriendliness, large‐scale applicability, and more. It is therefore not surprising that the search for the perfect antifouling coating has been going on for decades. With the discovery of metal‐based antifouling paints in the 1970s, fouling was thought to be a problem of the past, yet its untargeted toxicity led to serious ecological concern, and its use became prohibited. As a response, research shifted focus toward a biocompatible alternative: polymer‐based antifouling coatings. This has resulted in numerous advanced and innovative antifouling strategies, including fouling‐resistant, fouling‐release, and fouling‐degrading coatings. Here, these novel and exciting discoveries are highlighted while simultaneously assessing their antifouling performance and practical…

Abstract Soft polymer materials, which are similar to human tissues, have played critical roles in modern interdisciplinary research. Compared with conventional methods, 3D printing allows rapid prototyping and mass customization and is ideal for processing soft polymer materials. However, 3D printing of soft polymer materials is still in the early stages of development and is facing many challenges including limited printable materials, low printing resolution and speed, and poor functionalities. The present review aims to summarize the ideas to address these challenges. It focuses on three points: 1) how to develop printable materials and make unprintable materials printable, 2) how to choose suitable methods and improve printing resolution, and 3) how to directly construct functional structures/systems with 3D printing. After a brief introduction on this topic, the mainstream 3D printing technologies for printing soft polymer materials are reviewed, with an emphasis on improving printing resolution and speed, choosing suitable printing techniques, developing printable materials,…

Abstract Developing high‐performance and cost‐effective bifunctional electrocatalysts for large‐scale water electrolysis is desirable but remains a significant challenge. Most existing nano‐ and micro‐structured electrocatalysts require complex synthetic procedures, making scale‐up highly challenging. Here, a heterogeneous Ni 2 P‐Fe 2 P microsheet is synthesized by directly soaking Ni foam in hydrochloric acid and an iron nitrate solution, followed by phosphidation. Benefiting from high intrinsic activity, abundant active sites, and a superior transfer coefficient, this self‐supported Ni 2 P‐Fe 2 P electrocatalyst shows superb catalytic activity toward overall water splitting, requiring low voltages of 1.682 and 1.865 V to attain current densities of 100 and 500 mA cm −2 in 1 m KOH, respectively. Such catalytic performance is superior to the benchmark IrO 2 || Pt/C pair and also places this electrocatalyst among the best bifunctional catalysts reported thus far. Furthermore, its enhanced corrosion resistance and hydrophilic surface make it suitable for seawater splitting. It is able…

Abstract Phase‐change materials (PCMs) are seeing tremendous interest for their use in reconfigurable photonic devices; however, the most common PCMs exhibit a large absorption loss in one or both states. Here, Sb 2 S 3 and Sb 2 Se 3 are demonstrated as a class of low loss, reversible alternatives to the standard commercially available chalcogenide PCMs. A contrast of refractive index of Δ n = 0.60 for Sb 2 S 3 and Δ n = 0.77 for Sb 2 Se 3 is reported, while maintaining very low losses ( k < 10 −5 ) in the telecommunications C‐band at 1550 nm. With a stronger absorption in the visible spectrum, Sb 2 Se 3 allows for reversible optical switching using conventional visible wavelength lasers. Here, a stable switching endurance of better than 4000 cycles is demonstrated. To deal with the essentially zero intrinsic absorption losses, a new figure of merit (FOM) is introduced taking into account the measured waveguide losses when integrating these materials onto a standard silicon photonics platform. The FOM of 29 rad phase shift per dB of loss for Sb 2 Se 3 outperforms Ge 2 Sb 2 Te 5 by…

Abstract Functionalized carbon nanomaterials, as significant options for renewable energy systems, are widely utilized in diversified electrochemical reactions in virtue of property advantages. The inevitable defect sites in architectures greatly affect physicochemical properties of carbon nanomaterials, thus defect engineering has recently become a vital research orientation of carbon‐based electrocatalysts. The intentionally introduced intrinsic carbon defect sites in the frameworks can directly serve as the potential active sites owing to the altered surface charge state, modulated adsorption free energy of key intermediates, as well as diminished bandgap. Furthermore, the synergistic sites between intrinsic defects and heteroatom dopants/captured atomic metal species can further optimize the electronic structure and adsorption/desorption behavior, making carbon‐based catalysts comparable to commercial precious metal catalysts in electrocatalysis. With pressing research demands, the common configurations, construction strategies, structure–activity relationships, and…

Abstract Reducing green hydrogen production costs is essential for developing a hydrogen economy. Developing cost‐effective electrocatalysts for water electrolysis is thus of great research interest. Among various material candidates, transition metal phosphides (TMP) have emerged as robust bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) due to their various phases and tunable electronic structure. Recently, heterostructured catalysts have exhibited significantly enhanced activities toward HER/OER. The enhancement can be attributed to the increased amount of accessible active sites, accelerated mass/charge transfer, and optimized adsorption of intermediates, which arise from the synergistic effects of the heterostructure. Herein, a comprehensive overview of the recent progress of bifunctional TMP‐based heterostructure is introduced to provide an insight into their preparation and corresponding reaction mechanisms. It starts with summarizing general fundamental aspects of HER/OER and the synergistic effect of…

Abstract Zinc metal is considered as one of the best anode choices for rechargeable aqueous Zn‐based batteries due to its high specific capacity, abundance, and safety. However, dendrite and corrosion issues remain a challenge for this system. Herein, sieve‐element function (selective channel of Zn2+) and uniform‐pore distribution (≈3.0 nm) of a kaolin‐coated Zn anode (KL‐Zn) is proposed to alleviate these problems. Based on the artificial Zn metal/electrolyte interface, the KL‐Zn anode not only ensures dendrite‐free deposition and long‐time stability (800 h at 1.1 mA h cm−2), but also retards side reactions. As a consequence, KL‐Zn/MnO2 batteries can deliver high specific capacity and good capacity retention as well as a reasonably well‐preserved morphology (KL‐Zn) after 600 cycles at 0.5 A g−1. This work provides a deep step toward high‐performance rechargeable Zn‐based battery system.

Abstract Porous carbon materials have demonstrated exceptional performance in a variety of energy‐ and environment‐related applications. Over the past decades, tremendous efforts have been made in the coordinated design and fabrication of porous carbon nanoarchitectures in terms of pore sizes, surface chemistry, and structure. Herein, structure‐oriented carbon design and applications are reviewed. The unique properties of porous carbon materials that offer them promising design opportunities and broad applicability in some representative fields, including water remediation, CO 2 capture, lithium‐ion batteries, lithium–sulfur batteries, lithium metal anodes, Na‐ion batteries, K‐ion batteries, supercapacitors, and the oxygen reduction reaction are highlighted. Then, the most up‐to‐date strategies for structural control and functionalization of porous carbons are summarized, toward tailoring microporous, mesoporous, macroporous, and hierarchically porous carbons with disordered or ordered, amorphous or graphitic structures. Meanwhile, the emerging features of these structures in…

Abstract Post‐synthetic modification (PSM) of metal–organic framework (MOF) compounds is a useful technique for preparing new MOFs that can exhibit or enhance many of the properties of the parent MOFs. PSM can be carried out by a number of approaches such as modifying the linker (ligand) and/or metal node, and adsorption/exchange of guest species. The surface environment of the MOF can be modified to increase structural stability as well as introducing desired properties. There is considerable scope in widening the applications of the MOF with compatible metal or ligand employing the PSM. This review focuses on the recent developments of modified materials through PSM, which augers well for the chemical modification and functionalization of MOFs. In this review, different types of PSM methods are presented in an orderly manner, and the diverse applications of resultant frameworks are described and discussed.

Abstract Zinc–air batteries deliver great potential as emerging energy storage systems but suffer from sluggish kinetics of the cathode oxygen redox reactions that render unsatisfactory cycling lifespan. The exploration on bifunctional electrocatalysts for oxygen reduction and evolution constitutes a key solution, where rational design strategies to integrate various active sites into a high‐performance air cathode remain insufficient. Herein, a multiscale construction strategy is proposed to rationally direct the fabrication of bifunctional oxygen electrocatalysts for long‐lifespan rechargeable zinc–air batteries. NiFe layered double hydroxides and cobalt coordinated framework porphyrin are selected as the active sites considering their high intrinsic activity at the molecular level, and the active sites are successively integrated on three‐dimensional conductive scaffolds at mesoscale to strengthen ion transportation. Consequently, the multiscale constructed electrocatalyst exhibits excellent bifunctional performance (Δ E = 0.68 V), which is even better than that of the noble…

Abstract Noble metal nanoparticles due to their unique optical properties arising from their interactions with an incident light have been intensively employed in a broad range of applications. This review comprehensively describes fundamentals behind plasmonics, used to develop applications in the fields of biomedical, energy, and information technologies. Basic concepts (electromagnetic interaction and permittivity of metals) are discussed through Mie theory presented as the main model for interpreting phenomena of optical absorption and scattering. The effects of near‐field enhancement, shape, composition, and surrounding medium of nanoparticles on optical properties are described in detail. The review explores and identifies the potential of plasmonic nanoparticles based on their optical properties (e.g., light absorption, scattering, and field enhancement) for developing different applications (biomedical, energy and information technologies). Due to a significant impact of plasmonic nanoparticles on medicine and healthcare products and technologies, the review initially…

Abstract Searching for advanced microwave absorption (MA) nanomaterials is one of the most feasible ways to address the increasing electromagnetic pollution in both military and civil fields. To this end, graphene and MXene have won the widespread attention as the main representatives due to their remarkable structures and properties. The common features such as the large aspect ratio, active chemical surface, and varieties of synthesis processes endow graphene and MXene with unique superiorities for developing high‐efficiency MA structures, in particular lightweight assemblies and various hybrids. Meanwhile, the structural and performance differences (such as different conductivities) between them result in distinctive techniques in the design, fabrication, and application of their MA materials. Herein, the research progress in graphene‐ and MXene‐based MA materials is reviewed, with a special focus on advances in general strategies. Moreover, through the comparison between graphene‐ and MXene‐based MA materials, their respective advantages in achieving high‐performance MA are…

Abstract Developing highly efficient and stable electrocatalysts plays an important role in energy‐related electrocatalysis fields. Transition‐metal phosphides (TMPs) possess a series of advantages, such as high conductivity, earth‐abundance reserves, and good physicochemical properties, therefore arousing wide attention. In this review, the electrochemical activity origin of TMPs, allowing the rational design and construction of phosphides toward various energy‐relevant reactions is first discussed. Subsequently, their unique energy‐related electrocatalysis nature toward hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), hydrogen oxidation reaction (HOR), carbon dioxide reduction reaction (CO2RR), nitrogen reduction reaction (NRR), urea oxidation reaction (UOR), methanol oxidation reaction (MOR), and others is highlighted. Then, the TMPs’ synthetic strategies are analyzed and summarized systematically. Finally, the existing key issues, countermeasures, and the future challenges of TMPs toward efficient energy‐related…

Abstract With the unprecedentedly increasing demand for renewable and clean energy sources, the sodium‐ion battery (SIB) is emerging as an alternative or complementary energy storage candidate to the present commercial lithium‐ion battery due to the abundance and low cost of sodium resources. Layered transition metal oxides and Prussian blue analogs are reviewed in terms of their commercial potential as cathode materials for SIBs. The recent progress in research on their half cells and full cells for the ultimate application in SIBs are summarized. In addition, their electrochemical performance, suitability for scaling up, cost, and environmental concerns are compared in detail with a brief outlook on future prospects. It is anticipated that this review will inspire further development of layered transition metal oxides and Prussian blue analogs for SIBs, especially for their emerging commercialization.

Abstract The integration of nanomaterials with high conductivity into stretchable polymer fibers can achieve novel functionalities such as sensing physical deformations. With a metallic conductivity that exceeds other solution‐processed nanomaterials, 2D titanium carbide MXene is an attractive material to produce conducting and stretchable fibers. Here, a scalable wet‐spinning technique is used to produce Ti 3 C 2 T x MXene/polyurethane (PU) composite fibers that show both conductivity and high stretchability. The conductivity at a very low percolation threshold of ≈1 wt% is demonstrated, which is lower than the previously reported values for MXene‐based polymer composites. When used as a strain sensor, the MXene/PU composite fibers show a high gauge factor of ≈12900 (≈238 at 50% strain) and a large sensing strain of ≈152%. The cyclic strain sensing performance is further improved by producing fibers with MXene/PU sheath and pure PU core using a coaxial wet‐spinning process. Using a commercial‐scale knitting machine, MXene/PU fibers are knitted into a one‐piece elbow sleeve, which…

Abstract Poly(ethylene oxide) (PEO)‐based electrolytes are promising for all‐solid‐state batteries but can only be used above room temperature due to the high‐degree crystallization of PEO and the intimate affinity between ethylene oxide (EO) chains and lithium ions. Here, a homogeneous‐inspired design of PEO‐based solid‐state electrolytes with fast ion conduction is proposed. The homogeneous PEO‐based solid‐state electrolyte with an adjusted succinonitrile (SN) and PEO molar ratio simultaneously suppresses the PEO crystallization and mitigates the affinity between EO and Li + . By adjusting the molar ratio of SN to PEO (SN:EO ≈ 1:4), channels providing fast Li + transport are formed within the homogeneous solid‐state polymer electrolyte, which increases the ionic conductivity by 100 times and enables their application at a low temperature (0–25 °C), together with the uniform lithium deposition. This modified PEO‐based electrolyte also enables a LiFePO 4 cathode to achieve a superior Coulombic efficiency (>99%) and have a long life (>750 cycles) at room temperature. Moreover, even…

Abstract Among various classes of biomaterials, the majority of non‐centrosymmetric crystalline materials exhibit piezoelectric properties, i.e., the accumulation of charge in response to applied mechanical stress or deformation. Due to the growing interest in nanomaterials, piezoelectric nano‐biomaterials have been widely investigated, leading to remarkable advancements throughout the last two decades. Piezoelectric properties, high surface energy, targeting properties, and intricate cell–material interactions render piezoelectric nanomaterials highly attractive for application in therapeutics as well as regenerative medicine. Herein, the major focus is to highlight the wide range of applications of piezoelectric nano‐biomaterials in drug delivery, theranostics, and tissue regeneration. After a brief introduction to piezoelectricity, an overview is provided on the major classes of piezoelectric biomaterials as well as a description of the origin of biopiezoelectricity in different tissues and macromolecules. Subsequently, relevant properties and postfabrication strategies of…

Abstract Pressure sensors play an integral role in a wide range of applications, such as soft robotics and health monitoring. In order to meet this demand, many groups microengineer the active layer—the layer that deforms under pressure and dictates changes in the output signal—of capacitive, resistive/piezoresistive, piezoelectric, and triboelectric pressure sensors in order to improve sensor performance. Geometric microengineering of the active layer has been shown to improve performance parameters such as sensitivity, dynamic range, limit of detection, and response and relaxation times. There are a wide range of implemented designs, including microdomes, micropyramids, lines or microridges, papillae, microspheres, micropores, and microcylinders, each offering different advantages for a particular application. It is important to compare the techniques by which the microengineered active layers are designed and fabricated as they may provide additional insights on compatibility and sensing range limits. To evaluate each fabrication method, it is critical to take into account the…

Abstract Selective nitrate‐to‐ammonia electrochemical conversion is an efficient pathway to solve the pollution of nitrate and an attractive strategy for low‐temperature ammonia synthesis. However, current studies for nitrate electroreduction (NO3RR) mainly focus on metal‐based catalysts, which remains challenging because of the poor understanding of the catalytic mechanism. Herein, taking single transition metal atom supported on graphitic carbon nitrides (g‐CN) as an example, the NO3RR feasibility of single‐atom catalysts (SACs) is first demonstrated by using density functional theory calculations. The results reveal that highly efficient NO3RR toward NH3 can be achieved on Ti/g‐CN and Zr/g‐CN with low limiting potentials of −0.39 and −0.41 V, respectively. Furthermore, the considerable energy barriers are observed during the formation of byproducts NO2, NO, N2O, and N2 on Ti/g‐CN and Zr/g‐CN, guaranteeing their high selectivity. This work provides a new route for the application of SACs and paves the way to the development of NO3RR.

Abstract The complex tissue‐specific physiology that is orchestrated from the nano‐ to the macroscale, in conjugation with the dynamic biophysical/biochemical stimuli underlying biological processes, has inspired the design of sophisticated hydrogels and nanoparticle systems exhibiting stimuli‐responsive features. Recently, hydrogels and nanoparticles have been combined in advanced nanocomposite hybrid platforms expanding their range of biomedical applications. The ease and flexibility of attaining modular nanocomposite hydrogel constructs by selecting different classes of nanomaterials/hydrogels, or tuning nanoparticle‐hydrogel physicochemical interactions widely expands the range of attainable properties to levels beyond those of traditional platforms. This review showcases the intrinsic ability of hybrid constructs to react to external or internal/physiological stimuli in the scope of developing sophisticated and intelligent systems with application‐oriented features. Moreover, nanoparticle‐hydrogel platforms are overviewed in the context of encoding stimuli‐responsive cascades…

Abstract Ultraviolet photodetectors (UV PDs) with “5S” (high sensitivity, high signal‐to‐noise ratio, excellent spectrum selectivity, fast speed, and great stability) have been proposed as promising optoelectronics in recent years. To realize high‐performance UV PDs, heterojunctions are created to form a built‐in electrical field for suppressing recombination of photogenerated carriers and promoting collection efficiency. In this progress report, the fundamental components of heterojunctions including UV response semiconductors and other materials functionalized with unique effects are discussed. Then, strategies of building PDs with lattice‐matched heterojunctions, van der Waals heterostructures, and other heterojunctions are summarized. Finally, several applications based on heterojunction/heterostructure UV PDs are discussed, compromising flexible photodetectors, logic gates, and image sensors. This work draws an outline of diverse materials as well as basic assembly methods applied in heterojunction/heterostructure UV PDs, which will help to bring about new possibilities and…

Abstract In recent years, Prussian blue analogue (PBA) materials have been widely explored and investigated in energy storage/conversion fields. Herein, the structure/property correlations of PBA materials as host frameworks for various charge‐carrier ions (e.g., Na+, K+, Zn2+, Mg2+, Ca2+, and Al3+) is reviewed, and the optimization strategies to achieve advanced performance of PBA electrodes are highlighted. Prospects for further applications of PBA materials in proton, ammonium‐ion, and multivalent‐ion batteries are summarized, with extra attention given to the selection of anode materials and electrolytes for practical implementation. This work provides a comprehensive understanding of PBA materials, and will serve as a guidance for future research and development of PBA electrodes.

Abstract Photocatalytic H2O2 evolution through two‐electron oxygen reduction has attracted wide attention as an environmentally friendly strategy compared with the traditional anthraquinone or electrocatalytic method. Herein, a biomimetic leaf‐vein‐like g‐C3N4 as an efficient photocatalyst for H2O2 evolution is reported, which owns tenable band structure, optimized charge transfer, and selective two‐electron O2 reduction. The mechanism for the regulation of band structure and charge transfer is well studied by combining experiments and theoretical calculations. The H2O2 yield of CN4 (287 µmol h−1) is about 3.3 times higher than that of pristine CN (87 µmol h−1), and the apparent quantum yield for H2O2 evolution over CN4 reaches 27.8% at 420 nm, which is much higher than that for many other current photocatalysts. This work not only provides a novel strategy for the design of photocatalyst with excellent H2O2 evolution efficiency, but also promotes deep understanding for the role of defect and doping sites on photocatalytic activity.

Abstract The electrode/electrolyte interface plays a critical role in stabilizing the cycling performance and prolonging the service life of rechargeable batteries to meet the sustainable energy requirements of the mobile society. The understanding of interfaces is still at the preliminary stage due to the limited research techniques and variable properties with time and potential. Herein, the latest developments focused on the interfaces in rechargeable systems including the cathode electrolyte interphase (CEI) and solid electrolyte interphase (SEI) are reviewed. The possible formation mechanisms of the electrode/electrolyte interface are discussed, followed by the introduction of two key influencing factors, specific adsorption and solvated coordinate structure, which will dominate the formation of the interface. Finally, the structure and chemical composition of the interface as well as the possible transport mechanism of lithium ions in the interface and the strategies to regulate the pathway through the interface are presented in detail. This work sheds light on the fundamental…

Abstract 2D transition metal carbides and/or nitrides (MXenes), by virtue of high electrical conductivity, abundant surface functional groups and excellent dispersion in various solvents, are attracting increasing attention and showing competitive performance in energy storage and conversion applications. However, like other 2D materials, MXene nanosheets incline to stack together via van der Waals interactions, which lead to limited number of active sites, sluggish ionic kinetics, and finally ordinary performance of MXene materials/devices. Constructing 2D MXene nanosheets into 3D architectures has been proven to be an effective strategy to reduce restacking, thus providing larger specific surface area, higher porosity, and shorter ion and mass transport distance over normal 1D and 2D structures. In this review, the commonly used strategies for manufacturing 3D MXene architectures (3D MXenes and 3D MXene‐based composites) are summarized, such as template, assembly, 3D printing, and other methods. Special attention is also given to the structure–property relationships of 3D MXene…

Abstract Bimetallic nanoparticles of noble metals are of high interest in imaging, biomedical devices, including nanomedicine, and heterogeneous catalysis. Synthesis, properties, characterization, biological properties, and practical applicability of nanoparticles on the basis of platinum group metals and the coin metals Ag and Au are discussed, also in comparison with the corresponding monometallic nanoparticles. In addition to the parameters that are required to characterize monometallic nanoparticles (mainly size, size distribution, shape, crystallographic nature, surface functionalization, charge), further information is required for a full characterization of bimetallic nanoparticles. This concerns the overall elemental composition of a bimetallic nanoparticle population (ratio of the two metals) and the internal distribution of the elements in individual nanoparticles (e.g., the presence of homogeneous alloys, core–shell systems, and possible intermediate stages). It is also important to ensure that all particles are identical in terms of elemental composition, that is, that…

Abstract Microcosmic 3D hierarchical structural design has proved to be an effective strategy to obtain high‐performance microwave absorbers, although the treatments to low‐dimensional cells in monolithic framework are usually based on semiempirical rules. In this work, a hierarchical carbon fiber (CF)@MXene@MoS 2 (CMM) core‐sheath synergistic structure with tunable and efficient microwave absorption (MA) properties is fabricated by introducing self‐assembled Ti 3 C 2 T x MXene on the surface of CF and subsequent anchoring of MoS 2 . By the synergistic effects from the MXene sheath increasing the conductive loss and MoS 2 at the outermost layer improving the impedance matching, the MA performance of CMM can be effectively regulated and optimized: the optimal reflection loss is −61.51 dB with a thickness of 3.5 mm and the maximum effective absorption bandwidth covers the whole Ku‐band with 7.6 GHz at 2.1 mm. Meanwhile, the whole X‐band absorption can also be achieved with specific MoS 2 loading at an optimized thickness.

Abstract Aramid nanofibers (ANFs) are of great interest in various applications due to its 1D nanoscale, high aspect ratio, high specific surface area, excellent strength, and modulus as well as impressive chemical and thermal stabilities. It is considered as one of the most promising nano‐sized building blocks with excellent properties and has therefore drawn increasing attention since 2011. However, no review has summarized the research progress and the prospective challenges of ANF. Herein, the methods of ANF fabrication and their relative merits are comprehensively discussed together with the challenges and progress in the deprotonation method for preparing ANF. The fabrication methods and development of ANF‐based advanced materials with different macroscopic morphologies, including the 1D ANF aerogel fiber, 2D ANF film/nanopaper/coating, and 3D ANF gel and particle are also described. Furthermore, the applications of ANF in nanocomposite reinforcement, battery separators, electrical insulation nanopaper, flexible electronics, and adsorption and filtration media are presented.…

Abstract This Review is an overview of the unique characteristics of cyclodextrin in forming an inclusion complex via host–guest noncovalent interactions. The modification of cyclodextrin advances its application as a pharmaceutical solubilizer, fabrication of functional molecular machines such as polyrotaxane, polypseudorotaxane, and polycatenanes and grafting of cyclodextrin with different linear, branched chain polymers. The different stimuli‐based supramolecular assemblies involving cyclodextrin as a key mediator with linked triggering responses on payload release is highlighted. In addition, the applications of cyclodextrin in diagnostic imaging and medical devices is briefly demonstrated. Cyclodextrin is a relatively low cost, biocompatible, biodegradable, and highly explored material with low toxicity for drug formulation, drug delivery, and wide varieties of other biomedical applications such as those in medical devices fabrication, biosensor, tissue engineering, and bio‐imaging. The toxicological profile of cyclodextrin is well established and safe for human consumption in…

Abstract From Deep Blue to AlphaGo, artificial intelligence and machine learning are booming, and neural networks have become the hot research direction. However, due to the size limit of complementary metal–oxide–semiconductor (CMOS) transistors, von Neumann‐based computing systems are facing multiple challenges (such as memory walls). As the number of transistors required by the neural network increases, the development of neural networks based on the von Neumann computer is limited by volume and energy consumption. As the fourth basic circuit element, memristor shines in the field of neuromorphic computing. The new computer architecture based on memristor is widely considered as a substitute for the von Neumann architecture and has great potential to deal with the neural network and big data era challenge. This article reviews existing materials and structures of memristors, neurophysiological simulations based on memristors, and applications of memristor‐based neural networks. The feasibility and advancement of implementing neural networks using memristors are discussed, the…

Abstract Wearable and implantable bioelectronics are receiving a great deal of attention because they offer huge promise in personalized healthcare. Currently available bioelectronics generally rely on external aids to form an attachment to the human body, which leads to unstable performance in practical applications. Self‐adhesive bioelectronics are highly desirable for ameliorating these concerns by offering reliable and conformal contact with tissue, and stability and fidelity in the signal detection. However, achieving adequate and long‐term self‐adhesion to soft and wet biological tissues has been a daunting challenge. Recently, mussel‐inspired hydrogels have emerged as promising candidates for the design of self‐adhesive bioelectronics. In addition to self‐adhesiveness, the mussel‐inspired chemistry offers a unique pathway for integrating multiple functional properties to all‐in‐one bioelectronic devices, which have great implications for healthcare applications. In this report, the recent progress in the area of mussel‐inspired self‐adhesive bioelectronics is highlighted by…

Abstract The emerging electrochemical energy storage systems beyond Li‐ion batteries, including Na/K/Mg/Ca/Zn/Al‐ion batteries, attract extensive interest as the development of Li‐ion batteries is seriously hindered by the scarce lithium resources. During the past years, large amounts of studies have focused on the investigation of various electrode materials toward emerging metal‐ion batteries to realize high energy density, high power density, and a long cycle life. In particular, vanadium‐based nanomaterials have received great attention. Vanadium‐based compounds have a big family with different structures, chemical compositions, and electrochemical properties, which provide huge possibilities for the development of emerging electrochemical energy storage. In this review, a comprehensive overview of the recent progresses of promising vanadium‐based nanomaterials for emerging metal‐ion batteries is presented. The vanadium‐based materials are classified into four groups: vanadium oxides, vanadates, vanadium phosphates, and oxygen‐free vanadium‐based compounds. The structures,…

Abstract Neuromorphic computing (NC) is a new generation of artificial intelligence. Memristors are promising candidates for NC owing to the feasibility of their ultrahigh‐density 3D integration and their ultralow energy consumption. Compared to traditional electrical memristors, the emerging optoelectronic memristors are more attractive owing to their ability to combine the advantages of both photonics and electronics. However, the inability to reversibly tune the memconductance with light has severely restricted the development of optoelectronic NC. Here, an all‐optically controlled (AOC) analog memristor is realized, with memconductance that is reversibly tunable over a continuous range by varying only the wavelength of the controlling light. The device is based on the relatively mature semiconductor material InGaZnO and a memconductance tuning mechanism of light‐induced electron trapping and detrapping. It is found that the light‐induced multiple memconductance states are nonvolatile. Furthermore, spike‐timing‐dependent plasticity learning can be mimicked in this AOC memristor,…

Abstract The pores in metal–organic frameworks (MOFs) can be functionalized by placing chemical entities along the backbone and within the backbone. This chemistry is enabled by the architectural, thermal, and chemical robustness of the frameworks and the ability to characterize them by many diffraction and spectroscopic techniques. The pore chemistry of MOFs is articulated in terms of site isolation, coupling, and cooperation and relate that to their functions in guest recognition, catalysis, ion and electron transport, energy transfer, pore‐dynamic modulation, and interface construction. It is envisioned that the ultimate control of pore chemistry requires arranging functionalities into defined sequences and developing techniques for reading and writing such sequences within the pores.

Abstract 3D printing permits the construction of objects by layer‐by‐layer deposition of material, resulting in precise control of the dimensions and properties of complex printed structures. Although 3D printing fabricates inanimate objects, the emerging technology of 4D printing allows for animated structures that change their shape, function, or properties over time when exposed to specific external stimuli after fabrication. Among the materials used in 4D printing, hydrogels have attracted growing interest due to the availability of various smart hydrogels. The reversible shape‐morphing in 4D printed hydrogel structures is driven by a stress mismatch arising from the different swelling degrees in the parts of the structure upon application of a stimulus. This review provides the state‐of‐the‐art of 4D printing of hydrogels from the materials perspective. First, the main 3D printing technologies employed are briefly depicted, and, for each one, the required physico‐chemical properties of the precursor material. Then, the hydrogels that have been printed are described, including…

Abstract 2D/2D heterostructures can combine the collective advantages of each 2D material and even show improved properties from synergistic effects. 2D Transition metal carbide Ti 3 C 2 MXene and 2D 1T‐MoS 2 have emerged as attractive prototypes in electrochemistry due to their rich properties. Construction of these two 2D materials, as well as investigation about synergistic effects, is absent due to the instability of 1T‐MoS 2 . Here, 3D interconnected networks of 1T‐MoS 2 /Ti 3 C 2 MXene heterostructure are constructed by magneto‐hydrothermal synthesis, and the electrochemical storage mechanisms are investigated. Improved extra capacitance is observed due to enlarged ion storage space from a synergistically interplayed effect in 3D interconnected networks. Outstanding rate performance is realized because of ultrafast electron transport originating from Ti 3 C 2 MXene. This work provides an archetype to realize excellent electrochemical properties in 2D/2D heterostructures.

Abstract Heterostructured catalysts are hybrid materials that contain interfaces between their constituents formed through combinations of multiple solid‐state materials. The presence of multiple constituents institutes a synergistic effect that endows the catalyst with superior performance and appreciable potential in a diverse range of catalytic applications, including electrocatalytic and photocatalytic reduction of carbon dioxide. These promising catalysts can support a feasible method for large‐scale processing of valuable carbonaceous feedstock or fuel generation and alleviation of atmospheric carbon dioxide levels. Such technologies will serve as the much‐needed remedy for the global energy and environmental crisis. A broad spectrum of recently developed heterostructured catalysts pertaining to electrocatalytic and photocatalytic carbon dioxide reduction is evaluated. The insights included are of relevance to refresh fundamentals pertaining to the electron transfer processes leading to carbon dioxide reduction and the mechanistic reduction pathways yielding a possible…

Abstract Here, a novel macroporous hydrogel dressing is presented that can accelerate wound healing and guard against bacteria‐associated wound infection. Carboxymethyl agarose (CMA) is successfully prepared from agarose. The CMA molecular chains are cross‐linked by hydrogen bonding to form a supramolecular hydrogel, and the hydroxy groups in the CMA molecules complex with Ag+ to promote hydrogel formation. This hydrogel composite exhibits pH‐responsiveness and temperature‐responsiveness and releases Ag+, an antibacterial agent, over a prolonged period of time. Moreover, this hydrogel exhibits outstanding cytocompatibility and hemocompatibility. In vitro and in vivo investigations demonstrate that the hydrogel has enhanced antibacterial and anti‐inflammatory capabilities and can significantly accelerate skin tissue regeneration and wound closure. Astonishingly, the hydrogel can cause the inflammation process to occur earlier and for a shorter amount of time than in a normal process. Given its excellent antibacterial, anti‐inflammatory, and physicochemical properties, the broad…

Abstract Chemodynamic therapy (CDT), enabling selective therapeutic effects and low side effect, attracts increasing attention in recent years. However, limited intracellular content of H2O2 and acid at the tumor site restrains the lasting Fenton reaction and thus the anticancer efficacy of CDT. Herein, a nanoscale Co–ferrocene metal–organic framework (Co‐Fc NMOF) with high Fenton activity is synthesized and combined with glucose oxidase (GOx) to construct a cascade enzymatic/Fenton catalytic platform (Co‐Fc@GOx) for enhanced tumor treatment. In this system, Co‐Fc NMOF not only acts as a versatile and effective delivery cargo of GOx molecules to modulate the reaction conditions, but also possesses excellent Fenton effect for the generation of highly toxic •OH. In the tumor microenvironment, GOx delivered by Co‐Fc NMOF catalyzes endogenous glucose to gluconic acid and H2O2. The intracellular acidity and the on‐site content of H2O2 are consequently promoted, which in turn favors the Fenton reaction of Co‐Fc NMOF and enhances the generation of reactive oxygen species (ROS). Both in…

Abstract Polymer‐based solid electrolytes (PSEs) have attracted tremendous interests for the next‐generation lithium batteries in terms of high safety and energy density along with good flexibility. Remarkable performances have been demonstrated in PSEs, which endowed PSEs with the potential to replace liquid electrolytes to meet the market demands. In this review, polymer matrices, different polymer architectures, and functional filler materials used in PSEs are discussed to explore the design concepts, methodologies, working mechanisms, and pros and cons of various PSEs. In addition, their recent notable applications in all‐solid‐state lithium ion batteries, lithium–sulfur batteries, suppression of lithium dendrites, and flexible lithium batteries are also introduced. Finally, the challenges and future prospects are sketched to provide strategies to explore novel PSEs for high‐performance all‐solid‐state lithium batteries.

Abstract Hydrogen production via water electrocatalysis is limited by the sluggish anodic oxygen evolution reaction (OER) that requires a high overpotential. In response, a urea‐assisted energy‐saving alkaline hydrogen‐production system has been investigated by replacing OER with a more oxidizable urea oxidation reaction (UOR). A bimetal heterostructure CoMn/CoMn2O4 as a bifunctional catalyst is constructed in an alkaline system for both urea oxidation and hydrogen evolution reaction (HER). Based on the Schottky heterojunction structure, CoMn/CoMn2O4 induces self‐driven charge transfer at the interface, which facilitates the absorption of reactant molecules and the fracture of chemical bonds, therefore triggering the decomposition of water and urea. As a result, the heterostructured electrode exhibits ultralow potentials of −0.069 and 1.32 V (vs reversible hydrogen electrode) to reach 10 mA cm−2 for HER and UOR, respectively, in alkaline solution, and the full urea electrolysis driven by CoMn/CoMn2O4 delivers 10 mA cm−2 at a relatively low potential of 1.51 V and performs stably for…

Abstract With a certified efficiency as high as 25.2%, perovskite has taken the crown as the highest efficiency thin film solar cell material. Unfortunately, serious instability issues must be resolved before perovskite solar cells (PSCs) are commercialized. Aided by theoretical calculation, an appropriate multifunctional molecule, 2,2‐difluoropropanediamide (DFPDA), is selected to ameliorate all the instability issues. Specifically, the carbonyl groups in DFPDA form chemical bonds with Pb 2+ and passivate under‐coordinated Pb 2+ defects. Consequently, the perovskite crystallization rate is reduced and high‐quality films are produced with fewer defects. The amino groups not only bind with iodide to suppress ion migration but also increase the electron density on the carbonyl groups to further enhance their passivation effect. Furthermore, the fluorine groups in DFPDA form both an effective barrier on the perovskite to improve its moisture stability and a bridge between the perovskite and HTL for effective charge transport. In addition, they show an effective doping effect in the HTL…

Abstract One of the most promising fields for shape‐memory polymers is the biomedical field. Shape‐memory polymers that can be triggered by various (physiological) conditions such as temperature and moisture have been reported, as well as remotely triggerable shape‐memory polymers that make use of electromagnetic fields, ultrasound, etc. These polymers have shown great promise in in vitro studies as well as in early in vivo studies. Their biocompatibility, and in some cases biodegradability, renders them excellent candidates for minimal invasive surgery and for the design of triggerable biomedical devices. The current review provides a nonexhaustive overview of recent developments realized throughout the last decade in the field of shape‐memory polymers serving specific biomedical applications while considering relevant triggers and biocompatible chemistries.

Abstract With advantages such as high theoretical capacity, low cost, and nontoxicity, Zn metal has been widely investigated as an anode for aqueous batteries. However, the problems of dendrite formation and sustained corrosion originating from severe interfacial side reactions and uncontrolled Zn electrodeposition in aqueous electrolytes significantly slows down the practical application of Zn metal anodes. To address these issues, herein, an anti‐corrosion elastic constraint (AEC) is introduced that is built with nanosized TiO 2 and polyvinylidene fluoride (PVDF) matrix to Zn anode, where the PVDF layer serves as an elastic H 2 O/O 2 ‐blocking layer and the decorated TiO 2 nanoparticles assist uniform Zn electrodeposition. With this corrosion‐inhibition and electrodeposition‐redirection coating, the electrodeposition consistency and thermodynamic stability of the Zn anode are significantly improved, enabling a long‐term stable plating/stripping performance for 2000 h with an ultralow overpotential (<50 mV) and a high average Coulombic efficiency (>99.4%) for 1000 cycles without…

Abstract Modulating and constructing interface engineering is an efficient strategy to enhance catalytic activity for water splitting. Herein, a hybrid nanoarray structure of V‐CoP@a‐CeO 2 , where “a” represents amorphous, integrated into carbon cloth is fabricated for water splitting. The synergy effect between V and CeO 2 can increase the electron density of Co atoms at active sites, further optimizing the Gibbs free energy of H* adsorption energy (Δ G H* ). Besides, V‐CoP@a‐CeO 2 possesses lower water adsorption/dissociation energies, enabling accelerated reaction kinetics in alkaline media. As expected, the V‐CoP@a‐CeO 2 exhibits superior performance toward the hydrogen evolution reaction and the oxygen evolution reaction. More importantly, a two‐electrode electrolyzer combined with an electrocatalyst of V‐CoP@ a‐CeO 2 only demands that voltages of electrolytic cell are 1.56 and 1.71 V to achieve the current densities of 10 and 100 mA cm −2 , respectively. This work provides guidance for the design or optimization of materials for water electrolysis and beyond.

Abstract Solar‐driven conversion of CO2 into high value‐added fuels is expected to be an environmental‐friendly and sustainable approach for relieving the greenhouse gas effect and countering energy crisis. Metal sulfide semiconductors with wide photoresponsive range and favorable band structures are suitable photocatalysts for CO2 photoreduction. This review summarizes the recent progress on metal sulfide semiconductors for photocatalytic CO2 reduction. First, the fundamentals, mechanisms and some principles, like product selectivity, of photocatalytic CO2 reduction are introduced. Then, according to the elemental composition, the metal sulfide photocatalysts applied for CO2 reduction are classified into binary (CdS, ZnS, MoS2, SnS2, Bi2S3, In2S3,Cu2S, NiS/NiS2, and CoS2), ternary (ZnIn2S4, CdIn2S4, CuInS2, Cu3SnS4, and CuGaS2), and quaternary (Cu2ZnSnS4) systems, in which their crystal structures, photochemical characteristics, and photocatalytic CO2 reduction applications are systematically demonstrated. Especially, the diverse modification strategies for improving the activity…

The therapeutic benefits of mesenchymal stromal cell (MSC) transplantation have been attributed to their secreted factors, including extracellular vesicles (EVs) and soluble factors. The potential of employing the MSC secretome as an alternative acellular approach to cell therapy is being investigated in various tissue injury indications, but EVs administered via bolus injections are rapidly sequestered and cleared. However, biomaterials offer delivery platforms to enhance EV retention rates and healing efficacy. In this review, we highlight the mechanisms underpinning the therapeutic effects of MSC-EVs and soluble factors as effectors of immunomodulation and tissue regeneration, conferred primarily via their nucleic acid and protein contents. We discuss how manipulating the cell culture microenvironment or genetic modification of MSCs can further augment the potency of their secretions. The most recent advances in the development of EV-functionalized biomaterials that mediate enhanced angiogenesis and cell survival, while attenuating inflammation and fibrosis, are presented.…

Abstract Multifunctional micro‐force sensing in one device is an urgent need for the higher integration of the smaller flexible electronic device toward wearable health‐monitoring equipment, intelligent robotics, and efficient human–machine interface. Herein, a novel microchannel‐confined MXene‐based flexible piezoresistive sensor is demonstrated to simultaneously achieve multi‐types micro‐force sensing of pressure, sound, and acceleration. Benefiting from the synergistically confined effect of the fingerprint‐microstructured channel and the accordion‐microstructured MXene materials, the as‐designed sensor remarkably endows a low detection limit of 9 Pa, a high sensitivity of 99.5 kPa −1 , and a fast response time of 4 ms, as well as non‐attenuating durability over 10 000 cycles. Moreover, the fabricated sensor is multifunctionally capable of sensing sounds, micromotion, and acceleration in one device. Evidently, such a multifunctional sensing characteristic can highlight the bright prospect of the microchannel‐confined MXene‐based micro‐force sensor for the higher integration of…

Abstract Solar‐driven interfacial desalination (SDID), which is based on localized heating and interfacial evaporation, provides an opportunity for developing environmentally friendly and cost‐effective seawater thermal desalination. However, localized heating and rapidly generated interfacial steam may cause salt to accumulate on the evaporator's surface and block the channel of steam evaporation. Salt accumulation inevitably reduces the light absorption and service period of the solar absorber, resulting in a significant decrease in evaporation efficiency over time. Salt accumulation makes it difficult to produce SDID devices with high energy efficiency and long‐term stability for large‐scale use in remote poverty‐stricken areas. Therefore, the exploration of novel and effective strategies for addressing salt accumulation through both material design and structural engineering has attracted more attention in recent years. This review presents an overview of the state‐of‐the‐art advancements in salt‐resistant photothermal evaporation and discusses the critical issues for achieving…

Abstract MXenes have attracted increasing attention due to their unique advantages, excellent electronic conductivity, tunable layer structure, and controllable interfacial chemistry. However, the practical applications of MXenes in energy storage devices are severely limited by the issues of torpid reaction kinetics, limited active sites, and poor material utilization efficiency. Herein, the most‐up‐to date advances in the rational microstructure design to enhance electrochemical reaction kinetics and energy storage performance of MXene‐based materials are comprehensively summarized. This review begins with the preparation and properties of MXenes, classified into fluorine‐containing acid etching and fluoride‐free etching approaches. Afterwards, the interlayer structure design and interfacial functionalization of MXenes with respect to interlayer spacing and porous structure, terminal groups, and surface defects are summarized. Then the focus turns to the construction of advanced MXene‐based heterojunctions based on in situ derivation and surface self‐assembly. Based on these…

Abstract Graphene and graphene oxide (GO), as wonder materials, have penetrated nearly every field of research. One of their most attractive features is the functionality and assembly of graphene or GO, in which they can be considered to be chemically functionalized building blocks for creating unconventional porous graphene materials (PGMs) that not only combine the merits of both porous materials and graphene, but also have major advantages over other porous carbons for specific applications. The chemistry and approaches for functionalizing graphene and GO are first introduced, and typical procedures for pore creation (e.g., in‐plane pores, 2D laminar pores, and 3D interconnected pore assemblies), self‐assembly, and tailoring mechanisms for PGMs to highlight the significance of precise control over the pore morphology and pore size are summarized. Because of their unique pore structures, with different morphologies and intriguing properties, PGMs serve as key components in a variety of applications such as energy storage, electrocatalysis, and molecular separation. Finally, the…

Abstract A triboelectric nanogenerator (TENG) can convert energy in the surrounding environment to electricity. Therefore, in recent years, research related to TENGs has significantly increased owing to its simple and low‐cost manufacturing process, high portability, and high efficiency. The principle of the TENG lies in the coupling effect of contact electrification and electrostatic induction. Its output performance is directly proportional to the square of the surface charge density, which is related to friction materials. To increase the output power of a TENG and continuously provide electricity for other electronic equipment, many scholars have conducted detailed studies on the triboelectric properties of materials. Particularly, there has been research interest in the chemical functionalization of TENGs due to their unique advantages, such as high triboelectric charge density, durability, stability, and self‐cleaning properties. This Progress Report highlights the research progress in chemical modification methods for improving the charge density of TENGs, and classifies…

Abstract The family of transition metal carbides, nitrides, and carbonitrides (collectively called MXenes) has been a thriving field since the first invention of Ti 3 C 2 T x (MXene) in 2011. MXene is a new type of nanometer 2D sheet material, which exhibits great application potentials in various fields due to its multiple advantages such as high specific surface area, good electrical conductivity, and high mechanical strength. Electrocatalysis is regarded as the core of future clean energy conversion technologies, and MXene‐based materials provide inspiration for the design and preparation of electrocatalysts with high activity, high selectivity, and long loading life time. The applications of MXene‐based materials in electrocatalysis, including hydrogen evolution reaction, nitrogen reduction reaction, oxygen evolution reaction, oxygen reduction reaction, carbon dioxide reduction reaction, and methanol oxidation reaction are summarized in this review. As a crucial session regarding experiments, the current safer and more environmentally friendly preparation methods of MXene are…

Abstract The demand for computing power has been increasing exponentially since the emergence of artificial intelligence (AI), internet of things (IoT), and machine learning (ML), where novel computing primitives are required. Brain inspired neuromorphic computing systems, capable of combining analog computing and data storage at the device level, have drawn great attention recently. In addition, the basic electronic devices mimicking the biological synapse have achieved significant progress. Owing to their atomic thickness and reduced screening effect, the physical properties of 2D materials could be easily modulated by various stimuli, which is quite beneficial for synaptic applications. In this article, aiming at high‐performance and functional neuromorphic computing applications, a comprehensive review of synaptic devices based on 2D materials is provided, including the advantages of 2D materials and heterostructures, various robust multifunctional 2D synaptic devices, and associated neuromorphic applications. Challenges and strategies for the future development of 2D synaptic…

Abstract Searching for highly efficient, stable, and cost‐effective electrocatalysts for water splitting and oxygen reduction reaction (ORR) is critical for renewable energies, yet it remains a great challenge. Here, by performing an unbiased structural search and first‐principles calculations, the electrocatalytic performance of the emerging 2D transitional‐metal carbides, MC 2 (M represents the transition metal of Ti, V, Nb, Ta, and Mo, C is carbon), is systematically investigated. Owing to their super stability and outstanding electronic conductivity, fast charge transfer kinetics is allowed during catalysis. Specifically, NbC 2 , TaC 2 , and MoC 2 possess excellent hydrogen evolution reaction (HER) performance under the reaction by the Volmer‐Heyrovsky mechanism. Moreover, taking advantage of the dual‐active‐site catalytic mechanism for oxygen evolution reaction (OER) and ORR over traditional single‐active‐site mechanism, TaC 2 presents promising bifunctional electrocatalytic activity with a low overpotential of 0.06 and 0.37 V for HER and ORR, respectively. Meanwhile, the low…

Abstract Efficient electrocatalysts are key requirements for the development of ecofriendly electrochemical energy‐related technologies and devices. It is widely recognized that the introduction of vacancies is becoming an important and valid strategy to promote the electrocatalytic performances of the designed nanomaterials. In this review, the significance of vacancies (i.e., cationic vacancies, anionic vacancies, and mixed vacancies) on the improvement of electrocatalytic performances via three main functionalities, including tuning the electronic structure, regulating the active sites, and improving electrical conductivity, is systematically discussed. Recent achievements in vacancy engineering on various hotspot electrocatalytic processes are comprehensively summarized, with focus on the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), nitrogen reduction reaction (NRR), CO2 reduction reaction (CO2RR), and their further applications in overall water‐splitting and zinc–air battery devices. The recent development of vacancy…

Abstract Heterojunction engineering, especially 2D/2D heterojunctions, is regarded as a quite promising strategy to manipulate the photocatalytic performance of semiconductor catalysts. In this manuscript, a direct Z‐scheme 2D/2D heterojunction of CsPbBr 3 /Bi 2 WO 6 is designed and fabricated by a simple electrostatic self‐assembly process. By using ultrathin nanosheets with several atomic layers as the building blocks, a close CsPbBr 3 /Bi 2 WO 6 heterointerface over large area with quite a short charge transport distance is obtained, which enables a valid Z‐scheme interfacial charge transfer between Bi 2 WO 6 and CsPbBr 3 and thus boosts charge separation. The CsPbBr 3 /Bi 2 WO 6 heterojunction exhibits a superior photocatalytic performance toward CO 2 reduction. By incorporating Pt nanoparticles as the cocatalyst, a high photoelectron consumption rate of 324.0 µmol g −1 h −1 under AM 1.5G irradiation (150 mW cm −2 ) is obtained, which is 12.2 fold higher than that of CsPbBr 3 nanosheets. Moreover, a stable product yield of up to 1582.0 µ mol g −1 and electron consumption yield…

Abstract Membranes with ultrahigh ion selectivity and high liquid permeance are needed to produce high‐quality product water with increased recovery and process efficiency in water desalination. The narrow pore size distribution and controlled surface charge in the separation layer of nanofiltration membranes significantly improve the ion selectivity through molecular sieving and Donnan exclusion of co‐ions. Here, the ultraselective and yet highly water permeable polyamide nanofilm composite nanofiltration membranes developed by precisely controlling the kinetics of the interfacial polymerization reaction by maintaining the stoichiometric equilibrium at the interface is reported. The kinetically favorable stoichiometric equilibrium condition prohibits the formation of aggregate pores in the nanofilm and leads to the formation of narrow network pores with a high surface negative charge. Nanofilms are designed with a controlled degree of crosslinking and made as thin as ≈7 nm to achieve increased water permeance. The ultraselective membranes exhibit up to 99.99% rejection of divalent…

Abstract Additive manufacturing technology has attracted unprecedented attention in industry because it provides infinite possibilities for rapid prototyping and enormous potential and opportunities for the production of electronic devices of various complex shapes. This paper focuses on the progress of additive manufacturing of piezoelectric materials in recent years, summarizing the advantages of additive manufacturing technology and its technical impact on the production of piezoelectric materials. It identifies the likely future research development direction of additive manufacturing technology, as well as the limitations of the current additive manufacturing technology in the context of piezoelectric materials. First, the various processes involved in additive manufacturing of piezoelectric devices and the impact of various processes on device performance are systematically summarized. Then, the development of additive manufacturing technology and slurry preparation of piezoelectric ceramic materials, piezoelectric polymer materials, and piezoelectric composites are…

Abstract MXenes, a large family of 2D transition metal carbides or carbonitrides, possessing exceptional conductivity in the crystal core and ample functional groups (e.g., OH, F, O) on their surface, low energy barriers for metal ion diffusion, and large interlayer spaces for ion intercalation, are opening up various intriguing opportunities to construct advanced MXene‐based nanostructures for different‐type metal ion batteries (MIBs) with remarkable energy density and power density. Herein, this work summarizes the recent advances in MXene‐based nanostructures for high‐performance MIBs from lithium ion batteries to non‐lithium (Na + , K + , Mg 2+ , Zn 2+ , Ca 2+ ) ion batteries, in which the unique roles of MXenes as active materials, conductive substrates, and even current collectors are highlighted. Furthermore, the loaded model, encapsulated model, and sandwiched model are clarified in detail for MXene‐based hybrids with different dimensional (0D, 1D, and 2D) active materials, and each structural model is well exampled for different MIBs with special emphasis of synergistic…

Abstract Nitrogen doping has been proven to be a facile modification strategy to improve the electrochemical performance of 2D MXenes, a group of promising candidates for energy storage applications. However, the underlying mechanisms, especially the positions of nitrogen dopants, and its effect on the electrical properties of MXenes, are still largely unexplored. Herein, a comprehensive study is carried out to disclose the nitrogen doping mechanism in Ti 3 C 2 MXene, by employing theoretical simulation and experimental characterization. Three possible sites are found in Ti 3 C 2 T x (T = F, OH, and O) to accommodate the nitrogen dopants: lattice substitution (for carbon), function substitution (for –OH), and surface absorption (on –O). Moreover, electrochemical test results confirm that all the three kinds of nitrogen dopants are favorable for improving the specific capacitance of the Ti 3 C 2 electrode, and the underlying factors are successfully distinguished. By revealing the nitrogen doping mechanisms in Ti 3 C 2 MXene, this work provides theoretical guidelines for modulating…

Abstract Cesium‐based inorganic perovskites, such as CsPbI2Br, are promising candidates for photovoltaic applications owing to their exceptional optoelectronic properties and outstanding thermal stability. However, the power conversion efficiency of CsPbI2Br perovskite solar cells (PSCs) is still lower than those of hybrid PSCs and inorganic CsPbI3 PSCs. In this work, passivation and n‐type doping by adding CaCl2 to CsPbI2Br is demonstrated. The crystallinity of the CsPbI2Br perovskite film is enhanced, and the trap density is suppressed after adding CaCl2. In addition, the Fermi level of the CsPbI2Br is changed by the added CaCl2 to show heavy n‐type doping. As a result, the optimized CsPbI2Br PSC shows a highest open circuit voltage of 1.32 V and a record efficiency of 16.79%. Meanwhile, high air stability is demonstrated for a CsPbI2Br PSC with 90% of the initial efficiency remaining after more than 1000 h aging in air.

Abstract A solar‐thermal water evaporation structure that can continuously generate clean water with high efficiency and good salt rejection ability under sunlight is highly desirable for water desalination, but its realization remains challenging. Here, a hierarchical solar‐absorbing architecture is designed and fabricated, which comprises a 3D MXene microporous skeleton with vertically aligned MXene nanosheets, decorated with vertical arrays of metal–organic framework‐derived 2D carbon nanoplates embedded with cobalt nanoparticles. The rational integration of three categories of photothermal materials enables broadband light absorption, efficient light to heat conversion, low heat loss, rapid water transportation behavior, and much‐improved corrosion and oxidation resistance. Moreover, when assembling with a hydrophobic insulating layer with hydrophilic channel, the MXene‐based solar absorber can exhibit effective inhibition of salt crystallization due to the ability to advect and diffuse concentrated salt back into the water. As a result, when irradiating under one sun, the…

Abstract Phase, polarization, amplitude, and frequency represent the basic dimensions of light, playing crucial roles for both fundamental light–material interactions and all major optical applications. Metasurfaces have emerged as a compact platform to manipulate these knobs, but previous metasurfaces have limited flexibility to simultaneous control them. A multi‐freedom metasurface that can simultaneously and independently modulate phase, polarization, and amplitude in an analytical form is introduced, and frequency multiplexing is further realized by a k ‐space engineering technique. The multi‐freedom metasurface seamlessly combines geometric Pancharatnam–Berry phase and detour phase, both of which are frequency independent. As a result, it allows complex‐amplitude vectorial hologram at various frequencies based on the same design strategy, without sophisticated nanostructure searching of massive geometric parameters. Based on this principle, full‐color complex‐amplitude vectorial meta‐holograms in the visible are experimentally demonstrated with a metal–insulator–metal…

Abstract The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are crucial reactions in energy conversion and storage systems including fuel cells, metal–air batteries, and electrolyzers. Developing low‐cost, high‐efficiency, and durable non‐noble bifunctional oxygen electrocatalysts is the key to the commercialization of these devices. Here, based on an in‐depth understanding of ORR/OER reaction mechanisms, recent advances in the development of non‐noble electrocatalysts for ORR/OER are reviewed. In particular, rational design for enhancing the activity and stability and scalable synthesis toward the large‐scale production of bifunctional electrocatalysts are highlighted. Prospects and future challenges in the field of oxygen electrocatalysis are presented.

Abstract The severe hypoxia in solid tumors and the vicious aggregation‐caused fluorescence quenching (ACQ) of conventional photosensitizers (PSs) have limited the application of fluorescence imaging‐guided photodynamic therapy (PDT), although this therapy has obvious advantages in terms of its precise spatial–temporal control and noninvasive character. PSs featuring type I reactive oxygen species (ROS) based on free radicals and novel aggregation‐induced emission (AIE) characteristics (AIE‐PSs) could offer valuable opportunities to resolve the above problems, but molecular engineering methods are rare in previous reports. Herein, a strategy is proposed for generating stronger intramolecular charge transfer in electron‐rich anion‐π + AIE‐active luminogens (AIEgens) to help suppress nonradiative internal conversion and to promote radiative and intersystem crossing to boost free radical generation. Systematic and detailed experimental and theoretical calculations prove the proposal herein: the electron‐donating abilities are enhanced in collaborative donors, and the AIE‐PSs exhibit…

Abstract Similar to graphene and black phosphorus (BP), 2D transition metal carbides and nitrides (MXenes) are of great interest in a variety of fields, such as energy storage and conversion, sensors, electromagnetic interference (EMI) shielding, and photothermal therapy due to their excellent conductivity and hydrophilicity, large specific capacitance, high photothermal effect, and superior electrochemical performance. To further broaden applicable ranges beyond their existing boundaries and fully exploit these potentials, functional 2D MXene nanostructures in recent years have been rationally designed and developed by various approaches, such as doping strategies, surface functionalization, and hybridization, for next‐generation devices with the merits of low power consumption, intelligence, and high‐integration chips. This review provides an overview of the synthetic routes and fundamental properties of functional 2D MXene nanostructures, including surface‐modified 2D MXenes and mixed‐dimensional MXene‐based heterostructures, highlights the state‐of‐the‐art progress in the…

Abstract Zn dendrites growth and poor cycling stability are significant challenges for rechargeable aqueous Zn batteries. Zn metal deposition‐dissolution in aqueous electrolytes is typically determined by Zn anode–electrolyte interfaces. In this work, the role of a long‐chain polyethylene oxide (PEO) polymer as a multifunctional electrolyte additive in stabilizing Zn metal anodes is reported. PEO molecules suppress Zn 2+ ion transfer kinetics and regulate Zn 2+ ion concentration in the vicinity of Zn anodes through interactions between ether groups of PEO and Zn 2+ ions. The suppressed Zn 2+ ion transfer kinetics and homogeneous Zn 2+ ion distribution at the interface promotes dendrite‐free homogeneous Zn deposition. In addition, electrochemically inert PEO molecules adsorbed onto Zn anodes can protect the anode surfaces from H 2 generation and, thereby, enhance their electrochemical stability. Stable cycling over 3000 h and high reversibility (Coulombic efficiency > 99.5%) of Zn anodes is demonstrated in 1 m ZnSO 4 electrolyte with 0.5 wt% PEO. This finding provides helpful…

Abstract Microneedle (MN), a miniaturized needle with a length‐scale of hundreds of micrometers, has received a great deal of attention because of its minimally invasive, pain‐free, and easy‐to‐use nature. However, a major challenge for controlled long‐term drug delivery or biosensing using MN is its low tissue adhesion. Although microscopic structures with high tissue adhesion are found from living creatures in nature (e.g., microhooks of parasites, barbed stingers of honeybees, quills of porcupines), creating MNs with such complex microscopic features is still challenging with traditional fabrication methods. Here, a MN with bioinspired backward‐facing curved barbs for enhanced tissue adhesion, manufactured by a digital light processing 3D printing technique, is presented. Backward‐facing barbs on a MN are created by desolvation‐induced deformation utilizing cross‐linking density gradient in a photocurable polymer. Barb thickness and bending curvature are controlled by printing parameters and material composition. It is demonstrated that tissue adhesion of a backward‐facing barbed…

Abstract Porous organic molecular materials are a subclass of porous solids that are defined by their modular, molecular structures, and the absence of extended covalent or coordination bonding in the solid‐state. As a result, porous molecular materials are soluble and they can be processed into different forms, such as mixed matrix membranes. The structure of the porous modules can be fine‐tuned for specific applications, such as gas isotope separations, and in some cases the solid‐state properties of these materials can be defined by the structure of the porous molecule as viewed in isolation. In this review, the authors focus on the design of porous organic molecular materials and how their properties can be tuned for specific applications by using crystal engineering techniques. The authors distinguish between strategies where porosity is defined largely by the molecule itself, for example, in porous organic cages, and cases where porosity is generated by the solid‐state crystalline assembly. They emphasize the importance of computational techniques in the de novo design of…

Abstract Sodium metal anodes have attracted significant attention due to their high specific capacity (1166 mA h g −1 ), low redox potential ( − 2.71 V vs the standard hydrogen electrode), and abundant natural resources. Nevertheless, unstable solid electrolyte interphases (SEI) and uncontrolled dendrite growth critically hinder their commercialization. Notably, SEIs play a critical role in regulating Na deposition and improving the cycling stability of rechargeable Na metal batteries. Recently, SEI research on Na metal anodes has been intensively conducted worldwide; thus, a comprehensive review is necessary. Herein, initially, the fundamentals of SEI and the related issues induced by its intrinsic instability are discussed. Thereafter, advanced characterization techniques that unveil the morphological evolution and interfacial chemistry of Na metal anodes are presented. Subsequently, efficient strategies, including liquid electrolyte engineering, artificial SEI, and solid‐state electrolyte technology, to stabilize SEI films are outlined. Finally, key aspects and prospects in the…

Abstract Pursuit of advanced batteries with high‐energy density is one of the eternal goals for electrochemists. Over the past decades, lithium–sulfur batteries (LSBs) have gained world‐wide popularity due to their high theoretical energy density and cost effectiveness. However, their road to the market is still full of thorns. Apart from the poor electronic conductivity of sulfur‐based cathodes, LSBs involve special multielectron reaction mechanisms associated with active soluble lithium polysulfides intermediates. Accordingly, the electrode design and fabrication protocols of LSBs are different from those of traditional lithium ion batteries. This review is aimed at discussing the electrode design/fabrication protocols of LSBs, especially the current problems on various sulfur‐based cathodes (such as S, Li 2 S, Li 2 S x catholyte, organopolysulfides) and corresponding solutions. Different fabrication methods of sulfur‐based cathodes are introduced and their corresponding bullet points to achieve high‐quality cathodes are highlighted. In addition, the challenges and solutions of…

Abstract In recent years, magnetism has gained an enormous amount of interest among researchers for actuating different sizes and types of bio/soft robots, which can be via an electromagnetic‐coil system, or a system of moving permanent magnets. Different actuation strategies are used in robots with magnetic actuation having a number of advantages in possible realization of microscale robots such as bioinspired microrobots, tetherless microrobots, cellular microrobots, or even normal size soft robots such as electromagnetic soft robots and medical robots. This review provides a summary of recent research in magnetically actuated bio/soft robots, discussing fabrication processes and actuation methods together with relevant applications in biomedical area and discusses future prospects of this way of actuation for possible improvements in performance of different types of bio/soft robots.

Abstract MXenes with metallic conductivity, high pseudo‐capacitance and 2D structure, are promising flexible electrode materials for supercapacitors, but suffer from the restacking issue, which hinders ion accessibility and causes sluggish ion kinetics. Herein, a simple in situ ice template strategy is proposed to fabricate free‐standing, flexible 3D porous Ti 3 C 2 T x /carbon nanotubes (CNTs) film (3D‐PMCF) by freeze‐drying Ti 3 C 2 T x ‐based hydro‐films without any postprocessing. During the freeze‐drying process, small ice grains are in situ transformed from the residual water molecules in the Ti 3 C 2 T x interlayer and then act as a self‐sacrifice template to construct a 3D porous network. CNTs introduced in the hydro‐film increase the amount of interlayer water and the resultant porosity. The 3D structure of Ti 3 C 2 T x significantly increases the exposed surface active sites and accelerates the ion transport, meanwhile maintaining good flexibility. Consequently, the flexible 3D‐PMCF film delivers a capacitance of 375 F g −1 at 5 mV s −1 and retains 251.2 F g −1 at 1000 mV…

Abstract Poly(ethylene oxide) (PEO)‐based solid electrolytes are expected to be exploited in solid‐state batteries with high safety. Its narrow electrochemical window, however, limits the potential for high voltage and high energy density applications. Herein the electrochemical oxidation behavior of PEO and the failure mechanisms of LiCoO2‐PEO solid‐state batteries are studied. It is found that although for pure PEO it starts to oxidize at a voltage of above 3.9 V versus Li/Li+, the decomposition products have appropriate Li+ conductivity that unexpectedly form a relatively stable cathode electrolyte interphase (CEI) layer at the PEO and electrode interface. The performance degradation of the LiCoO2‐PEO battery originates from the strong oxidizing ability of LiCoO2 after delithiation at high voltages, which accelerates the decomposition of PEO and drives the self‐oxygen‐release of LiCoO2, leading to the unceasing growth of CEI and the destruction of the LiCoO2 surface. When LiCoO2 is well coated or a stable cathode LiMn0.7Fe0.3PO4 is used, a substantially improved electrochemical…

Abstract Conductive hydrogels are promising interface materials utilized in bioelectronics for human–machine interactions. However, the low‐temperature induced freezing problem and water evaporation‐induced structural failures have significantly hindered their practical applications. To address these problems, herein, an elaborately designed nanocomposite organohydrogel is fabricated by introducing highly conductive MXene nanosheets into a tannic acid‐decorated cellulose nanofibrils/polyacrylamide hybrid gel network infiltrated with glycerol (Gly)/water binary solvent. Owing to the introduction of Gly, the as‐prepared organohydrogel demonstrates an outstanding flexibility and electrical conductivity under a wide temperature spectrum (from −36 to 60 °C), and exhibits long‐term stability in an open environment (>7 days). Additionally, the dynamic catechol‐borate ester bonds, along with the readily formed hydrogen bonds between the water and Gly molecules, further endow the organohydrogel with excellent stretchability (≈1500% strain), high tissue adhesiveness, and self‐healing…

Abstract Safe, effective, and convenient administration of therapeutic nanomaterials is one of the greatest difficulties in nanomedicine. To tackle this challenge, a system which couples multi‐enzyme mimicking CeO 2 nanoparticles with clinically approved montmorillonite (MMT) for inflammatory bowel disease (IBD) therapy is reported. CeO 2 exhibits superoxide dismutase‐ and catalase‐like activities, and hydroxyl radical scavenging activity, making it more efficient at scavenging reactive oxygen species (ROS) than non‐catalytic antioxidants while being more stable than free enzymes. In addition, negatively‐charged MMT can be orally administered and specifically adsorbed onto positively‐charged inflamed colon tissue via electrostatic interactions for targeted delivery. When the two are assembled together by in situ growth of CeO 2 onto MMT, the optimized CeO 2 @MMT(1:9) is stable in the stomach for oral delivery, targets the inflamed colon through electrostatic interactions, and reduces inflammation through ROS scavenging, all without any significant systemic exposure as demonstrated…

Abstract According to the intercalation mechanism, an ordered modulation of channel structures of metal oxides is crucial to reversibly accumulate large zinc ions with high surface charge density for improving zinc‐ion battery performance. However, the irreversible structure‐transition commonly results in serious performance decay. Herein, polyanilines are in situ intercalated into the layered vanadium oxide in order to enlarge the lamellar spacing for enhancing the battery performance. With enlarged lattice spacing, the polyaniline intercalated vanadium oxide (PIVO) coupled with a Zn electrode exhibit a large specific capacity of 372 mAh g −1 and good cycling stability. More importantly, in situ characterization results reveal that PIVO allows the accumulation of additional zinc ions without obvious phase transformation and the conjugated polymeric chains enable the structure flexibility in the confined layer space to relieve the intercalation stress for improving cycling stability. Additionally, findings from the in situ infrared spectroscopy measurements elucidate the charge…

Abstract Nanoparticles have become a vital part of a vast number of established processes and products; they are used as catalysts, in cosmetics, and even by the pharmaceutical industry. Despite this, however, the reliable and reproducible production of functional nanoparticles for specific applications remains a great challenge. In this respect, reticular chemistry provides methods for connecting molecular building blocks to nanoparticles whose chemical composition, structure, porosity, and functionality can be controlled and tuned with atomic precision. Thus, reticular chemistry allows for the translation of the green chemistry principle of atom economy to functional nanomaterials, giving rise to the multifunctional efficiency concept. This principle encourages the design of highly active nanomaterials by maximizing the number of integrated functional units while minimizing the number of inactive components. State‐of‐the‐art research on reticular nanoparticles—metal‐organic frameworks, zeolitic imidazolate frameworks, and covalent organic frameworks—is critically assessed and the…

Abstract Double‐atom catalysts (DACs) have emerged as a novel frontier in heterogeneous catalysis because the synergistic effect between adjacent active sites can promote their catalytic activity while maintaining high atomic utilization efficiency, good selectivity, and high stability originating from the atomically dispersed nature. In this review, the recent progress in both experimental and theoretical research on DACs for various catalytic reactions is focused. Specifically, the central tasks in the design of DACs—manipulating the synergistic effect and engineering atomic and electronic structures of catalysts—are systematically reviewed, along with the prevailing experimental, characterization, and computational modeling approaches. Furthermore, the practical applications of DACs in water splitting, oxygen reduction reaction, nitrogen reduction reaction, and carbon dioxide reduction reaction are addressed. Finally, the future challenges for DACs are summarized and an outlook on the further investigations of DACs toward heterogeneous catalysis in high‐performance energy and…

Abstract Despite rapid development of adhesive hydrogels, the typical double‐sided adhesives fail to adhere to wet tissues and concurrently prevent postoperative tissue adhesion, thus severely limiting their applications in repair of internal tissues. Herein, a negatively charged carboxyl‐containing hydrogel is gradiently, electrostatically complexed with a cationic oligosaccharide by a one‐sided dipping method to form a novel Janus hydrogel wet adhesive whose two‐side faces demonstrate strikingly distinct adhesive and nonadhesive properties. The lightly complexed surface demonstrates instant robust adhesion to various wet biological tissues even under water since the phase separation induced by electrostatic complexation increases the hydrophobicity and water drainage capacity. Intriguingly, the highly complexed surface is non‐adhesive due to complete neutralization of carboxyls in the hydrogels. The Janus hydrogel can be used to replace traditional sutures to treat gastric perforation of rabbits. Animal experiment outcomes reveal that one side of the Janus hydrogel is firmly glued…

Abstract Electrically insulating polymer dielectrics with high energy densities and excellent thermal conductivities are showing tremendous potential for dielectric energy storage. However, the practical application of polymer dielectrics often requires mutually exclusive multifunctional properties such as high dielectric constants, high breakdown strengths, and high thermal conductivities. The rational assembly of 2D nanofillers of boron nitride nanosheets (BNNS) and reduced graphene oxide (rGO) into a well‐aligned micro‐sandwich structure in polyimide (PI) composites is reported. The alternating stacking of rGO and BNNS synergistically exploits the large difference in their electrical conductivities to yield a high dielectric constant with a moderate breakdown strength. Moreover, the distinctively separated rGO and BNNS layers give rise to higher thermal conductivities of composites than those containing mixed fillers because of reduced phonon scattering at the interfaces between two identical fillers, as verified by molecular dynamics simulations. Consequently, the micro‐sandwich…

Abstract Ionic liquids (ILs) have emerged as a novel class of chemical compounds for the development of advanced (multi)functional materials with outstanding potential in applications of several areas due to their unique properties and functionalities. The combination of ILs with polymers, in a composite, allows for developing smart materials, which synergistically combine the features of specific polymers and ILs. Moreover, ILs can be extensively modified by the incorporation of functional groups with specific properties into the cation, anion, or both. Thus, it is possible to tune the IL, the polymer, or both to obtain a broad spectrum of multifunctional composites and address the specific requirements of many applications. This work focusses on advanced materials and strategies concerning ILs and polymers for the development of smart IL/polymer‐based materials for applications including responsive and sensitive sensors, actuators, environment, batteries, fuel cells, and biomedical applications.

Abstract The development of adhesives that can achieve robust and repeatable adhesion to various surfaces underwater is promising; however, this remains a major challenge primarily because the surface hydration layer weakens the interfacial molecular interactions. Herein, a strategy is proposed to develop tough hydrogels that are robust, reusable, and long‐lasting for underwater adhesion. Hydrogels from cationic and aromatic monomers with an aromatic‐rich composition inspired by the amino acid residuals in barnacle cement proteins are synthesized. The hydrogels are mechanically strong and tough (elastic modulus 0.35 MPa, fracture stress 1.0 MPa, and fracture strain 720%), owing to the interchain π–π and cation–π interactions. In water, the hydrogels firmly adhere to diverse surfaces through interfacial electrostatic and hydrophobic interactions (adhesion strength of 180 kPa), which allows for instant adhesion and reversibility (50 times). Moreover, the hydrogel shows long‐lasting adhesion in water for months (100 days). Novel adhesive hydrogels may be useful in many applications,…

Abstract Developing an autonomous room temperature self‐healing supramolecular polyurethane (PU) with toughness and stiffness remains a great challenge. Herein, a novel concept that utilizes a T‐shaped chain extender with double amide hydrogen bonds in a side chain to extend PU prepolymers to construct highly stiff and tough supramolecular PU with integrated functions is reported. Mobile side‐chain H‐bonds afford a large flexibility to modulate the stiffness of the PUs ranging from highly stiff and tough elastomer (105.87 MPa Young's modulus, 27 kJ m −2 tearing energy), to solvent‐free hot‐melt adhesive, and coating. The dynamic side‐chain multiple H‐bonds afford an autonomous self‐healability at room temperature (25 ° C). Due to the rapid reconstruction of hydrogen bonds, this PU adhesive demonstrates a high adhesion strength, fast curing, reusability, long‐term adhesion, and excellent low‐temperature resistance. Intriguingly, the PU emits intrinsic blue fluorescence presumably owing to the aggregation‐induced emission of tertiary amine domains induced by side‐chain H‐bonds. The PU…

Abstract Textile devices have benefited from the discovery of new conductive materials and innovations in textile device design. These devices include textile‐based supercapacitors (TSCs), encompassing fiber, yarn, and fabric supercapacitors, which have demonstrated practical value in powering wearable devices. Recent review articles have highlighted the limited energy density of TSCs as an important challenge, demanding new electrode materials with higher electronic conductivity and theoretical capacitance than present materials. Ti 3 C 2 T x , a member of the MXene family, is known for its metallic conductivity and high volumetric capacitance in acidic electrolytes due to its pseudocapacitive behavior. Driven by these excellent properties, recent literature has reported promising integration methods of Ti 3 C 2 T x into TSCs with significantly improved areal and volumetric capacitance compared with non‐MXene‐based TSCs. Furthermore, knitted MXene‐based TSCs demonstrated practical application of wearable energy storage devices in textiles. Herein, the techniques used to produce…