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A porous NiFe LDH with abundant cationic defects was synthesized to optimize interactions between active Ni species and adsorbates, exhibiting a highly efficient seawater electrolysis performance.

Iridium (Ir)-based electrocatalysts are widely explored as benchmarks for acidic oxygen evolution reactions (OERs). However, further enhancing their catalytic activity remains challenging due to the difficulty in identifying active species and unfavorable architectures. In this work, we synthesized ultrathin Ir-IrO

Asymmetric hydrogenation based on heterogeneous metal nanoparticles (NPs) has attracted extensive attention for the production of chiral chemicals due to its high conversion efficiency, simple product separation, and convenient catalyst regeneration. Nevertheless, its further practical application is still impeded by the leaching of expensive chiral ligands and by the associated extra purification costs that are caused by the weak absorption of the chiral ligands on the metal NPs. In contrast, chiral metal–organic frameworks (CMOFs) have been proposed to serve as metal NP supports and chirality inducers via biomimicry of the configuration of privileged natural cinchona alkaloids on the single-chiral-site level. Among the presented engineered isoreticular valine (Val)-, serine (Ser)-, and threonine (Thr)-derived CMOFs, the Thr-MOF-supported Pt nanoparticles (NPs) exhibit impressive enantioselectivity in the asymmetric hydrogenation of ethyl pyruvate (EP) in addition to inherently robust catalytic recyclability without the need to add either fresh chiral ligands or Pt NPs.

The mechanical effects on carbon-based metal-free catalysts (C-MFCs) have rarely been explored although the C-MFCs have attracted worldwide interest as alternatives to the noble metal catalysts. Stress is everywhere, but a specialized study is strongly limited because the stress usually intermingles with other structural variables, including the dopants, defects, and interfaces in catalysis. Herein, we report a proof-of-concept study by establishing a platform to apply strain to a highly oriented pyrolytic graphite (HOPG) lamina continuously and collecting the electrochemical signals simultaneously. For the first time, the correlation between the surface strain of a graphitic carbon and its oxygen reduction reaction (ORR) activation effect is established. Results show that the in-plane and edge carbon sites in HOPG could not be further activated by applying tensile strain, but when the in-plane defects were involved in the structure, a strong and repeatable dependence of the catalytic activity on the tensile strain was observed, wherein ~ 35.0% improvement in ORR current density was realized by applying ~ 0.6% tensile strain. The density function theory (DFT) simulation shows that appropriate strain on the specific defect can optimize the adsorption of reaction intermediates, and the Stone-Wales defect on graphene correlates with the mechanical effect. Moreover, the effect was further authenticated by preparing a powdered graphene-based catalyst with varied strain-involved, which showed an apparent improvement of the ORR activity with ~ 0.4% surface strain. This work clarifies some basic principles of strain effects on graphitic carbon’s catalytic activities towards ORR, and may lay the foundation for developing carbon-based mechanoelectrocatalysis.

Room-temperature sodium-sulfur (RT-Na/S) batteries possess high potential for grid-scale stationary energy storage due to their low cost and high energy density. However, the issues arising from the low S mass loading and poor cycling stability caused by the shuttle effect of polysulfides seriously limit their operating capacity and cycling capability. Herein, sulfur-doped graphene frameworks supporting atomically dispersed 2H-MoS

Oxygen evolution reaction (OER) is an energy-determined half-reaction for water splitting and many other energy conversion processes, such as rechargeable metal-air batteries and CO

Photoelectrocatalytic (PEC) CO

Cation-tuning engineering has become a new frontier in altering the electronic structure of electrocatalysts, which has been employed to enhance their electrochemical performance. Significant efforts have been made to promote the electrochemical performance of transition metal-based materials during oxygen electrocatalysis and related energy devices such as Zn-air batteries. Herein, the advantages of cation-tuning engineering, including cation vacancies/defects and cation doping, in the modification of the electronic structure of transition metal oxide catalysts are discussed. Additionally, practical applications of the cation-tuning engineering strategy are reviewed in detail with a special emphasis on oxygen reduction reaction and oxygen evolution reaction. Lastly, challenges and future opportunities in this field are also proposed.

Despite the fact that high-valent nickel-based oxides exhibit promising catalytic activity for the urea oxidation reaction (UOR), the fundamental questions concerning the origin of the high performance and the structure-activity correlations remain to be elucidated. Here, we unveil the underlying enhanced mechanism of UOR by employing a series of prepared cation-vacancy controllable LiNiO

In this study, we developed a novel confinement-synthesis approach to layered double hydroxide nanodots (LDH-NDs) anchored on carbon nanoparticles, which formed a three-dimensional (3D) interconnected network within a porous carbon support derived from pyrolysis of metal-organic frameworks (C-MOF). The resultant LDH-NDs@C-MOF nonprecious metal catalysts were demonstrated to exhibit super-high catalytic performance for oxygen evolution reaction (OER) with excellent operation stability and low overpotential (∼230 mV) at an exchange current density of 10 mAcm−2. The observed overpotential for the LDH-NDs@C-MOF is much lower than that of large-sized LDH nanosheets (321 mV), pure carbonized MOF (411 mV), and even commercial RuO2 (281 mV). X-ray absorption measurements and density functional theory (DFT) calculations revealed partial charge transfer from Fe3+ through an O bridge to Ni2+ at the edge of LDH-NDs supported by C-MOF to produce the optimal binding energies for OER intermediates. This, coupled with a large number of exposed active sides and efficient charge and electrolyte/reactant/product transports associated with the porous 3D C-MOF support, significantly boosted the OER performance of the LDH-ND catalyst with respect to its nanosheet counterpart. Apart from the fact that this is the first active side identification for LDH-ND OER catalysts, this work provides a general strategy to enhance activities of nanosheet catalysts by converting them into edge-rich nanodots to be supported by 3D porous carbon architectures.

Flexible zinc–air batteries (ZABs) have been scrutinized as a type of promising flexible power source for next-generation electronic devices, but the batteries’ temperature adaptability has been a major hurdle due to their working features. Herein, we report a proof-of-concept study demonstrating that the structure of the air-cathode has an unexpected, significant influence on the temperature adaptability of flexible ZABs. An integrated stereoscopic air-cathode is developed to render enriched reactive triple-phase interfaces at the electrolyte–cathode interface, which enables favorable temperature adaptability in flexible ZABs. Besides, we rationalize that unlike other seal-structured batteries or capacitors, the plausible organohydrogels are not suitable as temperature-adaptive polyelectrolytes for high-performance flexible ZABs, which can instead be achieved by leveraging the interaction between water and terminal groups within polyelectrolyte backbones. As expected, the flexible ZABs developed via combining these two strategies show state-of-the-art electrochemical performances that greatly offset the influence of an extreme temperature change from −30 to 80 °C.

Chlorine gas is one of the most basic chemicals produced through electrolysis of brine solution and is a key raw material in many areas of industrial chemistry. In the past half a century, the dimensionally stable anode (DSA) made of RuO2 and TiO2 coated on the Ti substrate is the most widely used catalytic electrode for chlorine oxidation. However, the drawbacks of the DSA such as high cost, inferior selectivity and detrimental effects on the environment cannot meet the demand of modern industries. Recently, tremendous progress has been achieved in developing low-cost and efficient electrocatalysts for the chlorine evolution reaction (CER). Herein, a concise, but comprehensive and critical review is provided to summarize the recent advances in the field of electrocatalytic CER. First, the history of the chlor-alkali process and the catalytic mechanism of CER are summarized and presented. Then, three categories, namely, noble metal-based, earth-abundant transition-metal-based, and carbon-based metal-free electrocatalysts, are reviewed together with strategies for improving the CER catalytic performance. Lastly, future opportunities in this exciting field are outlined in terms of materials design, structure–performance relationship, technical improvements for the reactor and application scenarios extension.

Yolk-shelled silicon/carbon materials (YS-Si/C) are the most promising anode candidates to further improve the energy density of commercial lithium-ion batteries. Yet, limited conductive promotion and low tap density resulting from hollow spaces, and complex fabrication processes caused by employing various templating methods, are still critical issues for practical applications of YS-Si/C. In this work, a suite of YS-Si/C anode materials with confined Si-yolks by the C-shell without and with carbon nanotubes (each confines a Co3O4 nanoparticle on its tip) on the outer, inner and both sides of the C-shell were facilely and controllably synthesised. The best YS-Si/C anode with carbon nanotubes on both sides of the C-shell can achieve an excellent reversible capacity of 220 mAh g-1 under 40.0 A g-1 with 100% reversible capacity retention after 1200 cycles. Importantly, an electrochemical transmission electron microscope measurement system was assembled and applied for the concurrent in operando quantification of the exerted mechanical force and real-time structural responses of YS-Si/C during lithiation/delithiation and Li dendrite formation/dissolution processes, which can be used to gain new insights into the phenomenological structural changes, providing valuable guidance for the rational structural design of high-performance electrode materials.

The emerging chirality in nanomaterials represents one of the most dynamic areas in modern science. Although many novel chiral nanomaterials have been reported, the origin of their chirality and related optical activity have been not unveiled unambiguously. Thanks to the fast development of noble metal cluster chemistry, the structures of many chiral nanoclusters (CNCs) have been precisely determined and their chirality origin has been decoded as four different levels including chiral ligand, helix staple motif, asymmetry metal kernel, and chiral arrangement of organic ligands. Generally, the strong optical activity associated with the electron transitions of the noble metal core is popularly reported among CNCs protected by chiral ligands, following the so-called “outside-in” chirality transfer theory, namely, from organic ligand to metal core. Exceptionally, inherent chiral structures are discerned inside CNCs consisting of achiral ligands, such as the helix staples found in Au38(SR)24 and Au102(SR)44 (SR = thiolate) and the chiral metal kernel existing in Au20(PP3)4Cl4 (PP3 = tris(2-(diphenylphosphino)ethyl) phosphine). These chiral nanostructures induce distinct optical activity and even present reversed chirality transformation in the case of Au38(SR)24 (i.e., from chiral core structure to organic ligand). In the past decade, our group has carried out extensive research work on preparation, enantioseparation, optical activity, and application of chiral inorganic nanostructures. As representatives, enantiopure right-handed and left-handed Au20(PP3)4Cl4 clusters of intrinsic kernel chirality were acquired through an innovative supramolecular self-assembly method and their circular dichroism (CD) feature involving only the metal core was systematically studied; Au3[R/S-Tol-BINAP]3Cl (R/S-Tol-BINAP: R/S-2,2′-bis(di-p-tolylphosphino)-1,1′-binaphthyl) clusters with the smallest metal-atom number among the reported CNCs were designed and synthesized by using the privileged chiral Tol-BINAP ligand, which exhibited not only strongly enhanced CD signal also remarkable circular polarized luminescence (CPL) response as self-assembled into monodispersed nanocubes. In this Account, we aim at reviewing the fast development of CNCs featuring strong chiral attributes and optical activity. We will briefly introduce the preparation methods of CNCs, such as direct synthesis, ligand exchange, and enantioseparation. In the following parts, the commonly used tools for characterizing the chirality of CNCs are summarized, including CD, vibrational circular dichroism (VCD), CPL, single X-ray diffraction, nuclear magnetic resonance (NMR), and theoretical prediction. Then, the optical activity of CNCs will be systematically discussed, especially their CD, VCD, and CPL activity along with their chirality origin. Finally, future strategies for fabricating CNCs possessing strong optical activity as well as potential chirality-related applications will be proposed. We believe that this Account will trigger more research interest to not only study the amazing optical activity of CNCs but also employ them in many fields.

Summary Transition metal-based nanomaterials represent an emerging class of highly active and low-cost precatalysts for the oxygen evolution reaction (OER) in alkaline electrolyzers. However, most OER precatalysts undergo slow or incomplete self-reconstructions to generate real active sites, which is a time-consuming process for achieving high OER performance. Thus, we report a new class of OER precatalysts that can achieve highly active OER species by a rapid and deep self-reconstruction (denoted by SELF-RECON). The precatalysts with a core-shell structure comprising NiMoO4 (core) and NiFe/NiFeOx nanoparticles in N-doped amorphous carbons (shell) (denoted by NiMoFeO@NC), can realize rapid MoO42− dissolution and fast formation of NiOOH with Fe incorporation simultaneously. In situ Raman spectroscopy together with electron microscopy, X-ray photoelectron spectroscopy, and electrochemical tests indicate that the obtained NiFeOOH/NiFe-LDH after SELF-RECON behave as the real active species that outperform NiMoFeO@NC, with ultralow overpotentials and extraordinary long-term stability.

Summary Single-atom catalysts (SACs) have the advantages of both homogeneous and heterogeneous catalysts, which show promising application potentials in many renewable energy-conversion technologies and critical industrial processes. In particular, carbon-supported SACs (CS-SACs) are of great interest because of their maximal atom utilization (∼100%), unique physicochemical structure, and beneficial synergistic effects between active catalytic sites and carbon substrates. In this review, we offer a critical overview of the unique advantages of CS-SACs related to their material designs, catalytic activities, and potential application areas. The state-of-the-art design and synthesis of CS-SACs are described under the framework of bottom-up and top-down approaches. We also comprehensively summarize recent advances in developing CS-SACs for important electrochemical reactions, i.e., oxygen reduction reaction, hydrogen evolution reaction, oxygen evolution reaction, CO2 reduction reaction, nitrogen reduction reaction, serving as bi-/multi-functional electrocatalysts, and usages in supercapacitors and batteries. Lastly, the critical challenges and future opportunities in this emerging field are highlighted.

Metal–organic frameworks (MOFs) are increasingly being investigated as electrocatalysts for the oxygen evolution reaction (OER). Despite their promising catalytic activity, many fundamental questions concerning their structure−performance relationships—especially those regarding the roles of active species—remain to be answered. Here we show the structural transformation of a Ni0.5Co0.5-MOF-74 during the OER by operando X-ray absorption spectroscopy analysis and high-resolution transmission electron microscopy imaging. We suggest that Ni0.5Co0.5OOH0.75, with abundant oxygen vacancies and high oxidation states, forms in situ and is responsible for the high OER activity observed. The ratio of Ni to Co in the bimetallic centres alters the geometric and electronic structure of as-formed active species and in turn the catalytic activity. Based on our understanding of this system, we fabricate a Ni0.9Fe0.1-MOF that delivers low overpotentials of 198 mV and 231 mV at 10 mA cm−2 and 20 mA cm−2, respectively. Metal–organic frameworks (MOFs) are increasingly being explored for electrocatalytic oxygen evolution, which is half of the water splitting reaction. Here the authors show that, under reaction conditions, mixed metal oxyhydroxides form at the nodes of bimetallic MOFs, which are highly catalytically active.

Tungsten carbide (WC) with imperfect structures determined by phase engineering and heteroatom doping has attracted a great deal of attention with respect to hydrogen evolution reaction (HER). Howe...

At present, various strategies are utilized to improve the specific capacity of electrode materials to overcome the low energy density problem of aqueous battery, while their specific capacity is still far away from the theoretical value, especially for anode materials. Herein, we designed and synthesized nanoparticles assembled hollow hexagonal prism Bi2O3 (HHP Bi2O3) through template inducing synthesis. When used as an anode material for aqueous battery, it demonstrated a remarkable specific capacity of 327 mAh/g at 1 A/g, which reaches 94.8% of its theoretical capacity and is the highest value of its kind. Besides the high specific capacity, the as-fabricated HHP Bi2O3 also exhibits superior rate capability (220 mAh/g at 20 A/g) and long-term stability (~80%, 3000 cycles). Such high performance originates from high atom utilization and fast reaction kinetics for electrochemical reaction brought by its unique structures. Notably, when the HHP Bi2O3 is paired with the cathode material NixCo1-x (OH)2 to form an aqueous alkaline battery, its high electrochemical property is well exhibited. The designed HHP Bi2O3 with scalable synthesis process provides guidance for the preparation of other high capacity energy-storage materials, and paves the way to promote their practicality.

Summary Smart textiles for electricity generation are a superior energy solution with greatly improved convenience and comfort for wearable bioelectronics. However, maintaining the sustainability and stability of the power supply, though highly desirable, remains a great challenge. Here, we present a photo-rechargeable fabric with economically viable materials and scalable fabrication technologies. The fabric was able to constantly deliver electric power for 10 min at 0.1 mA after being charged for 1 min under the standard 1-sun condition. It can also work normally under twisted and watery circumstances and hold the stored energy for over 60 days without significant voltage loss. The photo-rechargeable fabric was demonstrated to power a body area sensor network for personalized healthcare.

Summary Internet-connected clothing/textiles is a promising but underexplored option for future personalized health care. Here, we report a textile-based sensor (TS) system with art design for wearable biomonitoring and interacting over the Internet. The TS is capable of delivering a sensitivity up to 3.88 V/kPa for ambient tiny pressure sensing. Made of durable materials, the TS exhibits remarkable robustness after more than 80,000 cycles of continuous operation. A wireless biomonitoring system (WBS) has been developed for timely processing of the acquired human pulse wave signals, wirelessly transmitting and displaying the patient’s health data via an APP interface onto a smartphone. The WBS was used to effectively diagnose obstructive sleep apnea-hypopnea syndrome during a whole night of sleep even with body movements. The textile-based wireless biomonitoring system represents a solid step toward constructing a body area network for personalized health care in the era of the Internet of Things.

Atomically precise gold (Au) nanoclusters (NCs) as visible light photosensitizers supported on the substrate for photoredox catalysis have attracted considerable attentions. However, efficient control of their photocatalytic activity and long-term stability is still challenging. Herein, we report a coordination-assisted self-assembly strategy in combination with electrostatic interaction to sandwich Au25(Capt)18 (abbreviated as Au25, Capt = captopril) NCs between an inner core and an outer shell made of UiO-66, denoted as UiO-66@Au25@UiO-66. Notably, the sandwich-like nanocomposite displays significantly enhanced catalytic activity along with an excellent stability when used in the selective photocatalytic aerobic oxidation of sulfide to sulfoxide. As comparison, Au25 NCs simply located at the outer surface or insider matrix of UiO-66 (short as Au25/UiO-66 and Au25@UiO-66) show poor stability and low conversion, respectively. This structure regulated difference in the catalytic performances of three nanocomposites is assigned to the varied distribution of active sites (Au NCs) in metal-organic frameworks (MOFs). This work offers the opportunity for application of nanoclusters in catalysis, energy conversion and even biology.

Flexible zinc-air batteries (ZAB) are a promising battery candidate for emerging flexible electronic devices, but the catalysis-based working principle and unique semi-opened structure pose a severe challenge to their overall performance at cold temperature. Herein, we report the first flexible rechargeable ZAB with excellent low-temperature adaptability, based on the innovation of an efficient electrocatalyst to offset the electrochemical performance shrinkage caused by decreased temperature and a highly conductive hydrogel with a polarized terminal group to render the anti-freezing property. The fabricated ZABs show excellent electrochemical performances that outperform those of many aqueous ZABs at room temperature. They also deliver a high capacity of 691 mAh g-1 and an energy density of 798 Wh kg-1 at -20 °C (92.7 % and 87.2 % retention of the room temperature counterparts, respectively), together with excellent flexibility and reverting capability.

Although manganese oxide (MnO2) has long been considered as a promising electrode material for pseudocapacitors due to its high theoretical capacity and large potential window, its rapid capacity fading severely impedes its further large-scale applications. Herein, an electron affinity regulation strategy is developed to inhibit the dissolution of Mn2+ during the charging and discharging process. Remarkably, fluoride (F−) substituted MnO2 (MnOF) nanosheets exhibit an exceptionally high durability (no obvious degradation after 100 000 cycles even at a high scan rate of 200 mV s−1) along with an enhanced capacitance in an aqueous (Na2SO4) electrolyte, which is superior to that of all the reported MnOx electrodes and comparable to that of carbon-based electrodes. DFT calculations and X-ray fine structure characterization reveal that the non-equilibrium F substitution in MnO2 induces the enhanced energy barrier (ΔG) of the Mn(III) disproportionation reaction and greatly stabilizes the Mn–O bond, which are the key in boosting cycling life.

Hydrogen production from direct water electrolysis has long been pursued as a key that may revolutionize the hydrogen economy. With the rapid availability of electricity generated using renewable energy resources, this long-pursued target is now closer to reality than ever before. To date, most studies regarding electrocatalytic hydrogen evolution reaction (HER) are carried out in strong acidic/alkali electrolytes. However, hydrogen production from HER under extreme pH conditions has several drawbacks, including a corrosive working environment, the requirement of expensive anion/cation exchange membranes, and acidic/alkali withstanding electrocatalysts. The more sustainable approach to address these drawbacks is to deploy neutral/near-neutral electrolytes for HER. Regretfully, both theoretical discussions and practical applications regarding HER under neutral/near-neutral conditions are relatively rare and very elusive. In this review, we systematically discuss the current understandings of HER mechanisms under neutral conditions and analyze the influences of different types of neutral electrolytes. The most recent advances in the development of neutral HER electrocatalysts are summarized and exemplified, and general electrocatalyst design principles are highlighted. Lastly, we provide our perspective on the potential future research direction. We hope that this review inspires future endeavors to realize efficient HER for hydrogen production under neutral conditions.

Atomic substitutions at the tetrahedral site (A

The structure-activity correlation study of electrocatalysts is essential for improving conversion from electrical to chemical energy. Recently, increasing evidences obtained by operando characterization techniques reveal that the structural evolution of catalysts caused by the interplay with electric fields, electrolytes or reactants/intermediates brings about the formation of real active sites. Hence, it is time to summarize the structural evolution-related research advances and envisage their future developments. In this minireview, we first introduce the fundamental concepts associated with structural evolution ( e.g., catalyst, active site/center and stability/lifetime) and their relevance. Then, the multiple inducements of structural evolution and advanced operando characterizations are discussed. Lastly, a brief overview of structural evolution and its reversibility in heterogeneous electrocatalysis, especially for representative electrocatalytic oxygen evolution reaction (OER) and CO 2 reduction reaction (CO 2 RR), along with key challenges and opportunities, is highlighted.