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Beyond conventional electrocatalyst engineering, recent studies have unveiled the effectiveness of manipulating the local reaction environment in enhancing the performance of electrocatalytic reactions. The general principles and strategies of local environmental engineering for different electrocatalytic processes have been extensively investigated. This review provides a critical appraisal of the recent advancements in local reaction environment engineering, aiming to comprehensively assess this emerging field. It presents the interactions among surface structure, ions distribution and local electric field in relation to the local reaction environment. Useful protocols such as the interfacial reactant concentration, mass transport rate, adsorption/desorption behaviors, and binding energy are in-depth discussed toward modifying the local reaction environment. Meanwhile, electrode physical structures and reaction cell configurations are viable optimization methods in engineering local reaction environments. In combination with operando investigation techniques, we conclude that rational modifications of the local reaction environment can significantly enhance various electrocatalytic processes by optimizing the thermodynamic and kinetic properties of the reaction interface. We also outline future research directions to attain a comprehensive understanding and effective modulation of the local reaction environment. [ABSTRACT FROM AUTHOR]

Urea is one of the most essential reactive nitrogen species in the nitrogen cycle and plays an indispensable role in the water-energy-food nexus. However, untreated urea or urine wastewater causes severe environmental pollution and threatens human health. Electrocatalytic and photo(electro)catalytic urea oxidation technologies under mild conditions have become promising methods for energy recovery and environmental remediation. An in-depth understanding of the reaction mechanisms of the urea oxidation reaction (UOR) is important to design efficient electrocatalysts/photo(electro)catalysts for these technologies. This review provides a critical appraisal of the recent advances in the UOR by means of both electrocatalysis and photo(electro)catalysis, aiming to comprehensively assess this emerging field from fundamentals and materials, to practical applications. The emphasis of this review is on the design and development strategies for electrocatalysts/photo(electro)catalysts based on reaction pathways. Meanwhile, the UOR in natural urine is discussed, focusing on the influence of impurity ions. A particular emphasis is placed on the application of the UOR in energy and environmental fields, such as hydrogen production by urea electrolysis, urea fuel cells, and urea/urine wastewater remediation. Finally, future directions, prospects, and remaining challenges are discussed for this emerging research field. This critical review significantly increases the understanding of current progress in urea conversion and the development of a sustainable nitrogen economy. [ABSTRACT FROM AUTHOR]

Regulating site‐to‐site interactions between active sites can effectively tailor the electrocatalytic behavior of single‐atom catalysts (SACs). The conventional SACs suffer from low density of single atoms and lack of site‐to‐site interactions between them. Herein, a series of interactive Pt SACs with controllable Pt–Pt spatial correlation degree and local coordination environment is developed by integrating densely populated Pt single atoms in the sub‐lattice of a Co3O4 matrix. The obtained interactive Pt‐Co3O4 catalysts demonstrate remarkable electrocatalytic performance toward hydrogen production, outperforming those of isolated single atom‐ and nanoparticle‐based catalysts. The intrinsic catalytic activity of interactive Pt‐Co3O4 catalysts is closely dependent on the spatial structure of Pt sites with the adjusted d‐band center by regulating contents and atomic configuration of Pt sites. This work provides fundamental insights for the structure‐property relationship on interactive single active sites, which is expected to direct the rational design of highly efficient SACs. [ABSTRACT FROM AUTHOR]

Efficient catalyst design is important for lean‐electrolyte sulfur reduction in Li−S batteries. However, most of the reported catalysts were focused on catalyst‐polysulfide interactions, and generally exhibit high activity only with a large excess of electrolyte. Herein, we proposed a general rule to boost lean‐electrolyte sulfur reduction by controlling the catalyst‐solvent interactions. As evidenced by synchrotron‐based analysis, in situ spectroscopy and theoretical computations, strong catalyst‐solvent interaction greatly enhances the lean‐electrolyte catalytic activity and battery stability. Benefitting from the strong interaction between solvent and cobalt catalyst, the Li−S battery achieves stable cycling with only 0.22 % capacity decay per cycle with a low electrolyte/sulfur mass ratio of 4.2. The lean‐electrolyte battery delivers 79 % capacity retention compared with the battery with flooded electrolyte, which is the highest among the reported lean‐electrolyte Li−S batteries. [ABSTRACT FROM AUTHOR]

Electrocatalysts for high‐rate hydrogen evolution reaction (HER) are crucial to clean fuel production. Nitrogen‐rich 2D transition metal nitride, designated "nitridene", has shown promising HER performance because of its unique physical/chemical properties. However, its synthesis is hindered by the sluggish growth kinetics. Here for the first time using a catalytic molten‐salt method, we facilely synthesized a V−Mo bimetallic nitridene solid solution, V0.2Mo0.8N1.2, with tunable electrocatalytic property. The molten‐salt synthesis reduces the growth barrier of V0.2Mo0.8N1.2 and facilitates V dissolution via a monomer assembly, as confirmed by synchrotron spectroscopy and ex situ electron microscopy. Furthermore, by merging computational simulations, we confirm that the V doping leads to an optimized electronic structure for fast protons coupling to produce hydrogen. These findings offer a quantitative engineering strategy for developing analogues of MXenes for clean energy conversions. [ABSTRACT FROM AUTHOR]

We demonstrate a widely applicable method to alter the adsorption configuration of multi‐carbon containing reactants by no catalyst engineering but simply adjusting the local reaction environment of the catalyst surface. Using electrocatalytic acetone to propane hydrogenation (APH) as a model reaction and common commercial Pt/Pt‐based materials as catalysts, we found local H+ concentration can significantly influence the adsorption mode of acetone reactant, for example, in vertical or flat mode, and target product selectivity. Electrocatalytic measurement combined with in situ spectroscopic characterizations reveals that the vertically adsorbed acetone is favorable for propane production while the flatly adsorbed mode suppresses the reaction. DFT calculations indicate that the H coverage on catalyst surface plays a decisive role in the adsorption configuration of acetone. The increased local acidity can facilitate the adsorption configuration of acetone from flat to vertical mode and suppress the competing hydrogen evaluation reaction, which consequently enhances the APH selectivity. [ABSTRACT FROM AUTHOR]

Compared to modern fossil‐fuel‐based refineries, the emerging electrocatalytic refinery (e‐refinery) is a more sustainable and environmentally benign strategy to convert renewable feedstocks and energy sources into transportable fuels and value‐added chemicals. A crucial step in conducting e‐refinery processes is the development of appropriate reactions and optimal electrocatalysts for efficient cleavage and formation of chemical bonds. However, compared to well‐studied primary reactions (e.g., O2 reduction, water splitting), the mechanistic aspects and materials design for emerging complex reactions are yet to be settled. To address this challenge, herein, we first present fundamentals of heterogeneous electrocatalysis and some primary reactions, and then implement these to establish the framework of e‐refinery by coupling in situ generated intermediates (integrated reactions) or products (tandem reactions). We also present a set of materials design principles and strategies to efficiently manipulate the reaction intermediates and pathways. [ABSTRACT FROM AUTHOR]

Monitoring and controlling the reconstruction of materials under working conditions is crucial for the precise identification of active sites, elucidation of reaction mechanisms, and rational design of advanced catalysts. Herein, a Bi‐based metal–organic framework (Bi‐MOF) for electrochemical CO2 reduction is selected as a case study. In situ Raman spectra combined with ex situ electron microscopy reveal that the intricate reconstruction of the Bi‐MOF can be controlled using two steps: 1) electrolyte‐mediated dissociation and conversion of Bi‐MOF to Bi2O2CO3, and 2) potential‐mediated reduction of Bi2O2CO3 to Bi. The intentionally reconstructed Bi catalyst exhibits excellent activity, selectivity, and durability for formate production, and the unsaturated surface Bi atoms formed during reconstruction become the active sites. This work emphasizes the significant impact of pre‐catalyst reconstruction under working conditions and provides insight into the design of highly active and stable electrocatalysts through the regulation of these processes. [ABSTRACT FROM AUTHOR]

Alkaline water electrolysis enables the use of nonprecious metal‐based catalysts and therefore holds great promise for large‐scale generation of renewable hydrogen fuel, especially when driven by renewable energy sources such as solar and wind. However, the sluggish kinetics of the water adsorption and dissociation steps in the alkaline hydrogen evolution reaction (HER) lower its energy conversion efficiency. Recent achievements have proved that 3d‐metal (oxy)(hydr)oxides can accelerate these two kinetic processes and thereby improve the activity of diverse HER electrocatalysts from experimental and theoretical points of view. Moreover, a positive role of strong coupling between HER catalysts and 3d‐metal (oxy)(hydr)oxides has been discovered recently. In this minireview, a compendious introduction to recent progress is provided, including experiments and theory. Remarks on the challenges and perspectives in this rapidly developing field are also provided. [ABSTRACT FROM AUTHOR]

The electrochemical nitrogen reduction reaction (NRR) is a promising alternative to the energy‐intensive Haber–Bosch process for ammonia synthesis. Among the possible electrocatalysts, bismuth‐based materials have shown unique NRR properties due to their electronic structures and poor hydrogen evolution activity. However, identification of the active sites and reaction mechanism is still difficult due to structural and chemical changes under reaction potentials. Herein, in situ Raman spectroscopy, complemented by electron microscopy, is employed to investigate the structural and chemical transformation of the Bi species during the NRR. Nanorod‐like bismuth‐based metal–organic frameworks are reduced in situ and fragment into densely contacted Bi0 nanoparticles under the applied potentials. The fragmented Bi0 nanoparticles exhibit excellent NRR performance in both neutral and acidic electrolytes, with an ammonia yield of 3.25 ± 0.08 µg cm−2 h−1 at −0.7 V versus reversible hydrogen electrode and a Faradaic efficiency of 12.11 ± 0.84% at −0.6 V in 0.10 m Na2SO4. Online differential electrochemical mass spectrometry detects the production of NH3 and N2H2 during NRR, suggesting a possible pathway through two‐step reduction and decomposition. This work highlights the importance of monitoring and optimizing the electronic and geometric structures of the electrocatalysts under NRR conditions. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts (SACs) have great potential in electrocatalysis. Their performance can be rationally optimized by tailoring the metal atoms, adjacent coordinative dopants, and metal loading. However, doing so is still a great challenge because of the limited synthesis approach and insufficient understanding of the structure–property relationships. Herein, we report a new kind of Mo SAC with a unique O,S coordination and a high metal loading over 10 wt %. The isolation and local environment was identified by high‐angle annular dark‐field scanning transmission electron microscopy and extended X‐ray absorption fine structure. The SACs catalyze the oxygen reduction reaction (ORR) via a 2 e− pathway with a high H2O2 selectivity of over 95 % in 0.10 m KOH. The critical role of the Mo single atoms and the coordination structure was revealed by both electrochemical tests and theoretical calculations. [ABSTRACT FROM AUTHOR]

Vacancy engineering is an effective strategy to manipulate the electronic structure of electrocatalysts to improve their performance, but few reports focus on phosphorus vacancies (Pv). Herein, the creation of Pv in metal phosphides and investigation of their role in alkaline electrocatalytic hydrogen evolution reaction (HER) is presented. The Pv‐modified catalyst requires a minimum onset potential of 0 mV vs. RHE, a small overpotential of 27.7 mV to achieve 10 mA cm−2 geometric current density and a Tafel slope of 30.88 mV dec−1, even outperforms the Pt/C benchmark (32.7 mV@10 mA cm−2 and 30.90 mV dec−1). This catalyst also displays superior stability up to 504 hours without any decay. Experimental analysis and density functional theory calculations suggest Pv can weaken the hybridization of Ni 3d and P 2p orbitals, enrich the electron density of Ni and P atoms nearby Pv, and facilitate H* desorption process, contributing to outstanding HER activity and facile kinetics. [ABSTRACT FROM AUTHOR]

Cost‐effective carbon‐based catalysts are promising for catalyzing the electrochemical N2 reduction reaction (NRR). However, the activity origin of carbon‐based catalysts towards NRR remains unclear, and regularities and rules for the rational design of carbon‐based NRR electrocatalysts are still lacking. Based on a combination of theoretical calculations and experimental observations, chalcogen/oxygen group element (O, S, Se, Te) doped carbon materials were systematically evaluated as potential NRR catalysts. Heteroatom‐doping‐induced charge accumulation facilitates N2 adsorption on carbon atoms and spin polarization boosts the potential‐determining step of the first protonation to form *NNH. Te‐doped and Se‐doped C catalysts exhibited high intrinsic NRR activity that is superior to most metal‐based catalysts. Establishing the correlation between the electronic structure and NRR performance for carbon‐based materials paves the pathway for their NRR application. [ABSTRACT FROM AUTHOR]

Developing low‐cost, highly active, and stable bi‐functional oxygen reduction and evolutionreaction (ORR/OER) electrocatalysts for rechargeable metal‐air batteries has been regarded as a primary challengefor sustainable energy devices. Herein, for the first time we design and fabricate defective carbon nanotubes (CNTs) enriched with pyridinic nitrogenvia laser irradiation for oxygenelectrocatalysis. Mesopores with plentiful edges are produced on the surface of CNTs, which not only facilitate mass transfer throughout CNTs architecture, but also are favorable for the incorporation of pyridinic nitrogen serving as the active sites for ORR/OER. The as‐prepared catalyst shows dramatically enhanced catalytic activity with half‐wave potential of 0.84 V (vs. RHE) for ORR and an overpotential of 0.36 V for OER in alkaline medium. More importantly, it exhibits excellent Zinc‐air battery charge/discharge cycling stability. [ABSTRACT FROM AUTHOR]

Most fundamental studies of electrocatalysis are based on the experimental and simulation results obtained for bulk model materials. Some of these mechanistic understandings are inapplicable for more active nanostructured electrocatalysts. Herein, considering the simplest and most typical electrocatalytic process, the hydrogen evolution reaction, an alternative reaction mechanism is proposed for nanomaterials based on the identification of a new intermediate, which differs from those commonly known for the bulk counterparts. In-situ Raman spectroscopy and electrochemical thermal/kinetic measurements were conducted on a series of nanomaterials under different conditions. In high-pH electrolytes with negligible hydronium (H3O+) concentration in bulk phase, massive H3O+ intermediates are found generating on the catalytic surface during water dissociation and hydrogen adsorption processes. These H3O+ intermediates create a unique acid-like local reaction environment on nanostructured catalytic surfaces and cut the energy barrier of the overall reaction. Such phenomena on nanostructured electrocatalysts explain their widely observed anomalously high activity under high-pH conditions. Most of the current understanding on electrocatalysis is obtained on bulk catalysts but has not been fully verified on nanostructured materials. An alternative alkaline hydrogen evolution reaction mechanism is proposed here for nanostructured catalysts. [ABSTRACT FROM AUTHOR]

Heterogeneous electrocatalysis typically involves charge transfer between surface active sites and adsorbed species. Therefore, modulating the surface charge state of an electrocatalyst can be used to enhance performance. A series of negatively charged transition‐metal (Fe, Co, Ni, Cu,and NiCo) phosphides were fabricated by designing strong electronic coupling with hydr(oxy)oxides formed in situ. Physicochemical characterizations, together with DFT computations, demonstrate that strong electronic coupling renders transition‐metal phosphides negatively charged. This facilitates destabilization of alkaline water adsorption and dissociation to result in significantly improved H2 evolution. Negatively charged Ni2P/nickel hydr(oxy)oxide for example exhibits a significantly low overpotential of 138 mV at 100 mA cm−2, superior to that without strong electronic coupling and also commercial Pt/C. [ABSTRACT FROM AUTHOR]

Abstract: The hydrogen evolution reaction (HER) is a fundamental process in electrocatalysis and plays an important role in energy conversion for the development of hydrogen‐based energy sources. However, the considerably slow rate of the HER in alkaline conditions has hindered advances in water splitting techniques for high‐purity hydrogen production. Differing from well documented acidic HER, the mechanistic aspects of alkaline HER are yet to be settled. A critical appraisal of alkaline HER electrocatalysis is presented, with a special emphasis on the connection between fundamental surface electrochemistry on single‐crystal models and the derived molecular design principle for real‐world electrocatalysts. By presenting some typical examples across theoretical calculations, surface characterization, and electrochemical experiments, we try to address some key ongoing debates to deliver a better understanding of alkaline HER at the atomic level. [ABSTRACT FROM AUTHOR]

Free-standing single-crystalline NiFe-hydroxide nanoflake arrays grown in situ on nickel foam are synthesized using a simple hydrothermal method and they exhibit remarkable activity and durability for oxygen evolution in 1.0 M KOH, achieving a decreased overpotential of 235 mV to produce 10 mA cm−2 current density after long-term operation up to 100 h. [ABSTRACT FROM AUTHOR]

Efficient electrocatalyst is essential to develop water splitting technology for large-scale hydrogen production, especially using bifunctional earth-abundant alternative catalysts under alkaline and neutral conditions. NiFe-based oxides have promising activity towards the oxygen evolution (OER). However, they usually show unsatisfactory performance for the hydrogen evolution reaction (HER), due to their large particle size with limited active sites and poor conductivity. Herein, we report the synthesis of sulfur-incorporated NiFe 2 O 4 nanosheets on nickel foam (S-NiFe 2 O 4 /NF), composed of ultra-small nanoparticles (~ 2 nm), by a facile confined growth strategy with the assistance of thiourea. Due to the favorable 3D hierarchical structure, the self-supported electrocatalyst endows abundant active sites, high electrical conductivity and rapid mass transfer, thereby achieving remarkable catalytic performance for overall water splitting under alkaline and neutral conditions. Specifically, the optimal S-NiFe 2 O 4 /NF electrode requires only 1.65 and 1.95 V to deliver a current density of 10 mA cm −2 in 1.0 M KOH and 1.0 M PBS, respectively, outperforming that of the commercial Pt/C as well as its counterparts (i.e. S-NiO/NF, S-Fe 3 O 4 /NF and pure NiFe 2 O 4 /NF). In addition, the synthesis strategy developed here can be applied to other mixed transition metal oxides with similar morphology and structure for various applications, such as supercapacitors, metal-air batteries, and photocatalysis. [ABSTRACT FROM AUTHOR]

Engineering high-energy interfacial structures for high-performance electrocatalysis is achieved by chemical coupling of active CoO nanoclusters and high-index facet Mn3O4 nano-octahedrons (hi-Mn3O4). A thorough characterization, including synchrotron-based near edge X-ray absorption fine structure, reveals that strong interactions between both components promote the formation of high-energy interfacial Mn-O-Co species and high oxidation state CoO, from which electrons are drawn by MnIII-O present in hi-Mn3O4. The CoO/hi-Mn3O4 demonstrates an excellent catalytic performance over the conventional metal oxide-based electrocatalysts, which is reflected by 1.2 times higher oxygen evolution reaction (OER) activity than that of Ru/C and a comparable oxygen reduction reaction (ORR) activity to that of Pt/C as well as a better stability than that of Ru/C (95 % vs. 81 % retained OER activity) and Pt/C (92 % vs. 78 % retained ORR activity after 10 h running) in alkaline electrolyte. [ABSTRACT FROM AUTHOR]

In spite of recent advances in the synthesis of hollow micro/nanostructures, the fabrication of three-dimensional electrodes on the basis of these structures remains a major challenge. Herein, we develop an electrochemical sacrificial-template strategy to fabricate hollow Co3O4 microtube arrays with hierarchical porosity. The resultant unique structures and integrated electrode configurations impart enhanced mass transfer and electron mobility, ensuring high activity and stability in catalyzing oxygen and hydrogen evolution reactions. Impressively, the apparent performance can rival that of state-of-the-art noble-metal and transition-metal electrocatalysts. Furthermore, this bifunctional electrode can be used for highly efficient overall water splitting, even competing with the integrated performance of Pt/C and IrO2/C. [ABSTRACT FROM AUTHOR]

A universal technique has been proposed to sort two-dimensional (2D) sub-nanometer thin crystals (manganese dioxide MnO2 and molybdenum disulfide MoS2) according to their lateral dimensions. This technique is based on tuning the zeta potential of their aqueous dispersions which induces the selective sedimentation of large-sized 2D crystals and leaves the small-sized counterparts in suspension. The electrocatalytic properties of as-obtained 2D ultrathin crystals are strongly dependent on their lateral size. As a proof-of-concept study, the small-sized MnO2 nanocrystals were tested as the electrocatalysts for the urea-oxidation reaction (UOR), which showed outstanding performance in both half reaction and full electrolytic cell. A mechanism study reveals the enhanced performance is associated with the remarkable structural properties of MnO2 including ultrathin (ca. 0.95 nm), laterally small-sized (50-200 nm), and highly exposed active centers. [ABSTRACT FROM AUTHOR]

Free-standing flexible films, constructed from twodimensional graphitic carbon nitride and titanium carbide (with MXene phase) nanosheets, display outstanding activity and stability in catalyzing the oxygen-evolution reaction in alkaline aqueous system, which originates from the Ti-Nx motifs acting as electroactive sites, and the hierarchically porous structure with highly hydrophilic surface. With this excellent electrocatalytic ability, comparable to that of the stateof- the-art precious-/transition-metal catalysts and superior to that of most free-standing films reported to date, they are directly used as efficient cathodes in rechargeable zinc-air batteries. Our findings reveal that the rational interaction between different two-dimensional materials can remarkably promote the oxygen electrochemistry, thus boosting the entire clean energy system. [ABSTRACT FROM AUTHOR]

Engineering carbon materials as the bifunctional catalysts for both electrocatalytic oxygen reduction/evolution reactions (ORR/OER) is highly promising for the large-scale commercialization of regenerative fuel cells and rechargeable metal-air batteries. Codoping carbons with heteroatoms can achieve unique electronic structures and show tailored electrocatalytic capabilities by rationally regulating their dopants. Sulfur is one of the most important dopants from both experimental and theoretical perspectives. In this work, a novel, highly efficient and environmentally benign method for sulfur incorporation into carbon framework has been developed facilely on the basis of graphene oxide-polydopamine (GD) hybrids to derive the N, S-codoped mesoporous carbon nanosheets. 16.7 at% S can be conjugated to the GD hybrids associated with the S doping efficiency up to 6.1% after 800 °C pyrolysis, which is higher than most previous S doping approaches. The resultant N, S-codoped mesoporous carbon nanosheets exhibit superior performance with favorable kinetics and excellent durability as a bifunctional ORR and OER catalyst, which is much better than that of most reported metal-free doped carbon, even transition metal and noble metal catalysts. The high concentrations of multiple dopants, abundant porous architecture and good electron transfer ability are believed to significantly expedite the ORR and OER catalytic processes. In the light of physicochemical versatility and structural tunability of polydopamine (PDA), this work provides a universal platform towards further development of PDA-based carbon materials with heteroatom dopants as the highly efficient electrocatalysts. [ABSTRACT FROM AUTHOR]

A fundamental change has been achieved in understanding surface electrochemistry due to the profound knowledge of the nature of electrocatalytic processes accumulated over the past several decades and to the recent technological advances in spectroscopy and high resolution imaging. Nowadays one can preferably design electrocatalysts based on the deep theoretical knowledge of electronic structures, via computer-guided engineering of the surface and (electro)chemical properties of materials, followed by the synthesis of practical materials with high performance for specific reactions. This review provides insights into both theoretical and experimental electrochemistry toward a better understanding of a series of key clean energy conversion reactions including oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). The emphasis of this review is on the origin of the electrocatalytic activity of nanostructured catalysts toward the aforementioned reactions by correlating the apparent electrode performance with their intrinsic electrochemical properties. Also, a rational design of electrocatalysts is proposed starting from the most fundamental aspects of the electronic structure engineering to a more practical level of nanotechnological fabrication. [ABSTRACT FROM AUTHOR]

The electrocatalytic hydrogen-evolution reaction (HER), as the main step of water splitting and the cornerstone of exploring the mechanism of other multi-electron transfer electrochemical processes, is the subject of extensive studies. A large number of high-performance electrocatalysts have been developed for HER accompanied by recent significant advances in exploring its electrochemical nature. Herein we present a critical appraisal of both theoretical and experimental studies of HER electrocatalysts with special emphasis on the electronic structure, surface (electro)chemistry, and molecular design. It addresses the importance of correlating theoretical calculations and electrochemical measurements toward better understanding of HER electrocatalysis at the atomic level. Fundamental concepts in the computational quantum chemistry and its relation to experimental electrochemistry are also presented along with some featured examples. [ABSTRACT FROM AUTHOR]

Three types of silver/reduced grapheneoxide (Ag/rGO) nanocomposites(one doped with nitrogen and another two without) are synthesizedto investigate their atomic structures and the oxygen reduction reaction(ORR) performance with them as the electrocatalysts. For the firsttime, the bonding interaction between Ag and N in N doped rGO (N-rGO)is confirmed by both high resolution X-ray photoelectron spectroscopy(XPS) and surface enhanced Raman spectroscopy (SERS). The Ag/N-rGOshows excellent ORR performance, including very high onset potentialand current density, which outperforms those Ag/rGOs without N doping.Detailed electrochemical analysis shows that the ORR mechanism onAg/N-rGO is different from both Ag and N-rGO, and its excellent performanceis caused by the Ag–N bonding which alters the electronic structureof N-rGO. [ABSTRACT FROM AUTHOR]

Composition-adjustable spinel-type metal oxides, Mn xCo3− xO4− δ ( x=0.8-1.4), were synthesized in ethanol solutions by a rapid inorganic self-templating mechanism using KCl nanocrystals as the structure-directing agent. The Mn xCo3 xO4 δ materials showed ultrahigh oxygen evolution activity and strong durability in alkaline solutions, and are capable of delivering a current density of 10 mA cm−2 at 1.58 V versus the reversible hydrogen electrode in 0.1 M KOH solution, which is superior in comparison to IrO2 catalysts under identical experimental conditions, and comparable to the most active noble-metal and transition-metal oxygen evolution electrocatalysts reported so far. The high performance for catalytic oxygen evolution originates from both compositional and structural features of the synthesized materials. The moderate content of Mn doping into the spinel framework led to their improved electronic conductivity and strong oxidizing ability, and the well-developed porosity, accompanied with the high affinity between OH− reactants and catalyst surface, contributed to the smooth mass transport, thus endowing them with superior oxygen evolution activity. [ABSTRACT FROM AUTHOR]

A new class of highly efficient oxygen evolution catalysts has been synthesized through the self-assembly of graphitic carbon nitride nanosheets and carbon nanotubes, driven by π-π stacking and electrostatic interactions. Remarkably, the catalysts exhibit higher catalytic oxygen evolution activity and stronger durability than Ir-based noble-metal catalysts and display the best performance among the reported nonmetal catalysts. This good result is attributed to the high nitrogen content and the efficient mass and charge transfer in the porous three-dimensional nanostructure. [ABSTRACT FROM AUTHOR]

Due to the complex reaction network of the electrochemical CO 2 reduction reaction (CRR), developing highly selective electrocatalysts for desired products remains a major challenge. In this study, a series of Cu-based single atom alloys (M@Cu) with multiple active sites are modelled to investigate their CRR selectivity trends by evaluating various adsorption configurations and energetics. The hydrogen (H) and oxygen (O) affinity of the secondary metals in the M@Cu model catalysts are found to be effective descriptors in determining CRR selectivity. The observed product grouping offers valid theoretical elucidation for available reports of CRR selectivity trends for Cu-based alloy catalysts. It also provides further mechanistic insight into the CRR product selectivity for an extensive range of Cu-based bimetallic materials. The selectivity trend based on the intrinsic catalyst properties provides a rational design strategy for highly selective CRR electrocatalysts. Image 1 • A novel descriptor-based approach to predict CRR selectivity of catalysts is developed. • A series of Cu-based alloy models (M@Cu) are employed to explore their CRR selectivity by extensive thermodynamic analysis. • The M-H and M-O affinity in M@Cu catalysts are found to be effective descriptors in determining CRR selectivity. • The product distribution in our study matches well with the reported CRR selectivity trends in Cu-based bimetallic catalysts. • The selectivity based on intrinsic properties offers a rational design strategy for highly selective CRR electrocatalysts. [ABSTRACT FROM AUTHOR]

Monitoring and controlling the reconstruction of materials under working conditions is crucial for the precise identification of active sites, elucidation of reaction mechanisms, and rational design of advanced catalysts. Herein, a Bi‐based metal–organic framework (Bi‐MOF) for electrochemical CO2 reduction is selected as a case study. In situ Raman spectra combined with ex situ electron microscopy reveal that the intricate reconstruction of the Bi‐MOF can be controlled using two steps: 1) electrolyte‐mediated dissociation and conversion of Bi‐MOF to Bi2O2CO3, and 2) potential‐mediated reduction of Bi2O2CO3 to Bi. The intentionally reconstructed Bi catalyst exhibits excellent activity, selectivity, and durability for formate production, and the unsaturated surface Bi atoms formed during reconstruction become the active sites. This work emphasizes the significant impact of pre‐catalyst reconstruction under working conditions and provides insight into the design of highly active and stable electrocatalysts through the regulation of these processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Roadmap for the development of green ammonia production technologies. • Effective coupling of water electrolyzers and the Haber-Bosch synthesis loop. • Promising strategies to boost electrocatalytic nitrogen reduction performance. • New electrocatalytic processes to close the anthropogenic nitrogen cycle. Ammonia (NH 3), the second highest produced chemical in the world, is dominantly used for fertilizer production to underpin the modern agriculture, and recently attracts increasing interest as an energy-dense, carbon-neutral carrier for renewable energy. The present Haber-Bosch process for NH 3 production is energy-, emission-, and capital-intensive. Therefore, recent research efforts have been devoted to developing efficient alternatives with decreased carbon emissions, higher compatibility with renewables, and flexible operation. Electrocatalysis technologies represent a crucial role and great potentials, especially the electrocatalytic nitrogen reduction reaction (NRR). However, the achieved performance is still far from feasibility due to the intrinsic limitations from nitrogen activation and reaction system. In this Review, we first discussed the roadmap towards green NH 3 , critically assessed the challenges of NRR, and then focused on several emerging strategies beyond conventional catalyst design and engineering under ambient aqueous conditions, including electrolyte effect, operation pressure, Li-mediated reaction, reactor innovation, new N-transformation reactions, and redox-mediated catalysis. [ABSTRACT FROM AUTHOR]