Dual interfacial engineering of a Chevrel phase electrode material for stable hydrogen evolution at 2500 mA cm-2

Interlayer-bonded Ni/MoO2 electrocatalyst for efficient hydrogen evolution reaction with stability over 6000 h at 1000 mA cm-2

The mechanical stability of the catalytic electrodes used for hydrogen evolution reactions (HER) is crucial for their industrial applications in anion exchange membrane water electrolysis (AEM-WE). This study develops a corrosion strategy to construct a self-supported electrocatalyst (Int-Ni/MoO2) with high mechanical stability by anchoring the Ni/MoO2 catalytic layer with a dense interlayer of MoO2 nanoparticles. The Int-Ni/MoO2 exhibits a strengthened homostructural interface between the interlayer and catalytic layer, preventing the detachment of the catalyst during ultrasonic treatment. The blade-shaped catalytic layer reduces bubble shock and potential fluctuations at high current densities up to -6000 mA cm-2. As a result, the Int-Ni/MoO2 electrode exhibits a low overpotential of 73.2 ± 14.2 mV and long-term stability for 6000 h at -1000 mA cm-2 in a 1 M KOH solution. The Int-Ni/MoO2 assembled AEM-WE device demonstrates long-term stability at 1000 mA cm-2 for 1000 h with a very low degradation rate of 3.96 µV h-1.

Achieving highly efficient electrocatalytic hydrogen evolution with Co-doped MoS2 nanosheets

MoS2 is a promising hydrogen evolution reaction (HER) catalyst because of the Pt-like activity at the side edges, but the whole activity is restricted by the inert basal plane. Herein, Co-doped 1T-MoS2 nanosheets are grown on carbon cloth (CC) through hydrothermal synthesis and exhibit superior HER activity with an overpotential of 69 mV@10 mA cm-2 and a Tafel slope of 81.84 mV dec-1 as well as durability for over 100 h at 100 mA cm-2 in an alkaline medium. The detailed structural tests demonstrate that the improved HER activity is attributed to Co doping and the high 1T phase content. Co doping induces transformation from the 2H to the 1T phase (67%), and further TMA+ addition increases the doping amount and the 1T phase content (79%). The excellent durability is due to the strong interface binding between MoS2 nanosheets and CC associated with the heterogeneous nucleation and growth and the high growth temperature (230 °C). This provides an inspiration for developing efficient and stable MoS2 catalysts by element doping.

An Interlayer Anchored NiMo/MoO2 Electrocatalyst for Hydrogen Evolution Reaction in Anion Exchange Membrane Water Electrolysis at High Current Density

Noble metal-free electrodes for anion exchange membrane water electrolysis (AEM-WE) operating at high current densities are critical for sustainable hydrogen production. However, the massive amount of bubbles resulted in insufficient mass transfer and unevenly distributed local stress, which poses a major challenge in designing an efficient and robust hydrogen evolution catalyst. Herein, a facile chemical corrosion method is developed to synthesize an interlayer-anchored NiMo/MoO2 catalyst on a nickel foam (NF) substrate (NiMo/Int/NF) with high hydrogen evolution activity (overpotential of 80.2 ± 3.53 mV) and durability (stable for 5000 h) at 1000 mA cm-2 in 1 m KOH. The interlayer tightly anchors the catalytic layer to the substrate, providing high compressive strength and strong adhesion to mitigate the bubble shock at a high current density. In situ Raman and X-ray diffraction analyses reveal that the heterostructural catalytic layer can accelerate the hydrogen evolution reaction with increased local pH and high component utilization. Using NiMo/Int/NF as the cathode, the assembled noble metal-free AEM-WE device exhibits a low cell voltage of 1.78 V at 1000 mA cm-2 (significantly lower than that of a Pt/C-catalyzed cell (1.94 V)) while also showing excellent stability for 3000 h.

Challenges and Emerging Trends in Hydrogen Energy Industrialization: From Hydrogen Evolution Reaction to Storage, Transportation, and Utilization

Green hydrogen (H2) emerges as a sustainable alternative to fossil fuels, offering a clean method to store renewable energy through water electrolysis with high energy content and zero carbon emissions. While research largely focuses on specific aspects such as hydrogen evolution reaction (HER), seawater HER electrocatalysts, and electrolyzer development, these studies often overlook the broader hydrogen economy from an integrated industry chain perspective. This review bridges that gap by providing a comprehensive analysis of hydrogen energy industrialization, covering advancements in HER, seawater HER, and electrolyzers, all aim at enabling industrial-scale H2 production. It further explores innovations and challenges in hydrogen storage and transportation, as well as real-world projects spanning the green hydrogen supply chain. Additionally, life cycle assessment studies validate the environmental benefits of using renewable energy sources for green H2 production. Furthermore, this review highlights advancements in counter-oxygen evolution reactions and organic oxidation reactions, alongside strategies to mitigate competing chlorine evolution reactions. Through this comprehensive examination, this review aims to inform readers of the latest developments in hydrogen energy industrialization, explore its growth potential, and provide new insights to propel the hydrogen economy forward.

Dual Active Site Engineering in Porous NiW Bimetallic Alloys for Enhanced Alkaline Hydrogen Evolution Reaction

Utilizing dual active sites in electrocatalysts creates a synergistic effect, enabling the independent optimization of H2O dissociation and intermediate adsorption/desorption, which in turn enhances the efficiency of the hydrogen evolution reaction (HER). Herein, a porous NiW bimetallic alloy electrocatalyst using a dynamic H2 bubble template (DHBT) strategy is fabricated. This electrocatalyst capitalizes on the synergistic effect of dual active sites, achieving industrial-level current densities of 500 and 1000 mA cm-2 for HER in 1.0 M KOH, with low overpotentials of 198 and 264 mV, respectively. It also demonstrates excellent stability over a 200 h test. Theoretical studies reveal that alloying Ni with W shifts the d-band center (εd) of the W 5d orbital downward, which enhances *OH intermediate desorption and promotes H2O adsorption and dissociation at the W site, leading to increased active site availability. Meanwhile, this shift provides more accessible H* intermediates, further enhancing H2 production at the Ni2W1 hollow site. When the porous NiW bimetallic alloy electrocatalyst is implemented in a solar-driven water splitting system, it achieves a high solar-to-hydrogen (STH) conversion efficiency of 16.59%. This work underscores the effectiveness of dual active site electrocatalysts for sustainable H2 production.

Strategies for industrial-grade seawater electrolysis: from electrocatalysts and device design to techno-economic analysis

Seawater electrolysis offers a promising route for sustainable hydrogen production, utilizing abundant seawater to meet global energy demands while addressing environmental concerns. However, challenges such as inefficiencies, high costs, and reliance on noble metal catalysts hinder its practical implementation. This review examines the fundamental mechanisms of seawater electrolysis, focusing on the hydrogen and oxygen evolution reactions (HER and OER) at industrial-scale current densities. Key strategies for catalyst design, including interfacial engineering, structural optimization, and improved mass and electron transport, to enhance efficiency and stability are discussed. Additionally, device architecture and techno-economic considerations are explored to facilitate scalable, cost-effective deployment. By providing insights into advanced materials and system innovations, this review outlines pathways for integrating seawater electrolysis into large-scale sustainable energy solutions.

Obtaining materials from local sources: surface modification engineering enabled substrates for water splitting

The preparation of an efficient electrode is the key to achieving efficient overall water-splitting for H2 production. Substrate surface modification engineering (SSME) provides a feasible method for preparing self-supported electrodes with high active site utilization, fast mass transport, and a simple fabrication process. This review summarizes and discusses the recent advances in preparing transition-metal-based HER/OER electrocatalysts via SSME. We first highlight the description and advantages of SSME, followed by the detailed introduction of electrocatalysts prepared via the SSME, such as hydroxides, oxyhydroxides, chalcogenides, phosphides, and borides. Finally, we provide the challenges and perspectives. We hope that this review will provide inspiration for researchers and stimulate the development of water splitting technology.

Interface Effects in Metal-2D TMDs Systems: Advancing the Design and Development Electrocatalysts

2D transition metal dichalcogenides (2D TMDs) have emerged as promising candidates in electrocatalysis due to their unique band structures and tunable electronic properties. Nevertheless, establishing robust, low-resistance contacts between TMDs layers and conductive supports has remained a challenge. Their atomically thin nature makes these layers prone to structural disruption and undesired chemical interactions, hampering charge transfer and diminishing catalytic efficiency. Recently, the visualization of microscopic interface behaviors and atomic layer interactions between metals and 2D TMDs has led to the introduction of ohmic contact metal-TMDs electrocatalysts to address these challenges. Specifically, synergy at the metal-2D TMDs interface endows the catalyst with new functionalities, including enhanced redox activity and selective reactant immobilization, thus helping address core challenges in energy conversion and storage. This work first examines the fundamental structural traits of 2D TMDs and introduces design principles and strategies for ohmic metal-TMDs composites in electrocatalysis. The discussion covers methods for adjusting work function differences, constructing edge contacts in TMDs, incorporating interface doping/insertion, and engineering orbital hybridization or bonding interfaces. Additionally, this work analyzes the advantages, limitations, and future prospects of each approach, offering valuable insights for the development of efficient metal-semiconductor catalysts, electrodes, and energy conversion and storage devices.

In Situ Li+ Intercalation into Nanosized Chevrel Phase Mo6S8 toward Efficient Electrochemical Nitroarene Reduction

Electrochemical nitroarene reduction enables the green production of anilines at ambient conditions thanks to the manipulated transfer of multiple electrons and protons via controlling potentials and currents, but challenges remain in pH-neutral electrolysis using nonprecious catalysts. Here, Chevrel phase Mo6S8 with high conductivity and insertable frameworks is proposed for the first time as a cost-efficient candidate with prominent performance and, more importantly, as a new platform to unravel cation effects on nitroarene electroreduction. Nanosized Mo6S8 derived from polymer-confined sulfidation affords a high yield (∼95%) and Faradaic efficiency (∼99%) for reducing 4-nitrostyrene to 4-aminostyrene at -0.45 V (vs RHE) in 0.1 M LiClO4, outperforming a series of counterparts of metal sulfides and even noble metals. The combination of experimental and theoretical analyses identifies an intercalation-correlated cation effect, expanding the current knowledge limited to the outer Helmholtz plane of electrodes. In situ Li+ intercalation into Mo6S8 cavities during electrolysis ameliorates the electronic configurations and thereby promotes the adsorption of the nitro group on low-coordinated Mo sites for hydrogenation via a proton-coupled electron transfer mechanism. Furthermore, the efficient electrosynthesis of aniline derivatives with conserved reducing groups from a wide range of substrates highlights the promise of Mo6S8 for electrochemical refinery.

Cu Intercalation-Stabilized 1T' MoS2 with Electrical Insulating Behavior

The intercalated two-dimensional (2D) transition metal dichalcogenides (TMDCs) have attracted much attention for their designable structures and novel properties. Among this family, host materials with low symmetry such as 1T' phase TMDCs are particularly interesting because of their potentials in inducing unconventional phenomena. However, such systems typically have low quality and poor stability, hindering further study of the structure-property relationship and applications. In this work, we intercalated Cu into 1T' MoS2 with high crystallinity and high thermal stability up to ∼300 °C. We identified the distribution and arrangement of Cu intercalators for the first time, and the results show that Cu intercalators occupy partially the tetrahedral interstices aligned with Mo sites. The obtained Cu-1T' MoS2 exhibits an insulating hopping transport behavior with a large temperature coefficient of resistance reaching -4∼-2%·K-1. This work broadens the artificial intercalated structure library and promotes the structure design and property modulation of layered materials.

Optimized Bubble Dynamics of 3D-Printed Electrodes for Enhanced Water Splitting

Gas evolution plays an important role in water electrolysis, as sluggish bubble dynamics lead to blockage of active sites, reduced catalytic performance, and even detachment of the catalysts. In this work, we present a strategy to fabricate highly rough three-dimensional (3D)-printed Ni (3DPNi) electrodes with ordered flow channel structures, achieving exceptional catalytic performance through enhanced bubble detachment and transport dynamics. The rough surfaces enhance hydrophilic and aerophobic properties, suppressing bubble coalescence and accelerating bubble detachment dynamics. The ordered structures of 3DPNi serve as efficient bubble flow channels and effectively prevent bubble trapping, facilitating rapid bubble transport dynamics. Collectively, these features optimize bubble dynamics, significantly boosting catalytic performance for water electrolysis. Computational fluid dynamics simulations and visual experiments validate the improved bubble dynamics. When coated with NiFe-LDH (NiFe-LDH/3DPNi), a low overpotential of 238 mV is required to deliver 100 mA cm-2 for OER. In overall water splitting, the NiFe-LDH/3DPNi || Pt plate setup requires a cell voltage of 1.86 V to achieve 1 A cm-2 and demonstrates excellent stability over 100 h at this current density, indicating strong potential for practical applications.

State-of-the-Art Light-Driven Hydrogen Generation from Formic Acid and Utilization in Enzymatic Hydrogenations

A concept of combining photocatalytically generated hydrogen with green enzymatic reductions is demonstrated. The developed photocatalytic formic acid (FA) dehydrogenation setup based on Pt(x)@TiO2 shows stable hydrogen generation activity, which is two orders of magnitude higher than reported values of state-of-the-art systems. Mechanistic studies confirm that hydrogen generation proceeds via a photocatalytic pathway, which is entirely different from purely thermal reaction mechanisms previously reported. The viability of the presented approach is demonstrated by the synthesis of value-added compounds 3-phenylpropanal and (2R, 5S)-dihydrocarvone at ambient pressure and room temperature, which should be applicable for many other hydrogenation processes, e. g., for the preparation of flavours and fragrance compounds, as well as pharmaceuticals.

High-Entropy Alloy Nanoflower Array Electrodes with Optimizable Reaction Pathways for Low-Voltage Hydrogen Production at Industrial-Grade Current Density

Developing sufficiently effective non-precious metal catalysts for large-current-density hydrogen production is highly significant but challenging, especially in low-voltage hydrogen production systems. Here, we innovatively report high-entropy alloy nanoflower array (HEANFA) electrodes with optimizable reaction pathways for hydrazine oxidation-assisted hydrogen production at industrial-grade current densities. Atomic-resolution structural analyses confirm the single-phase solid-solution structure of HEANFA. The HEANFA electrodes exhibit the top-level electrocatalytic performance for both the alkaline hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR). Furthermore, the hydrazine oxidation-assisted splitting (OHzS) system assembled with HEANFA as both anode and cathode exhibits a record-breaking performance for hydrogen production. It achieves ultralow working voltages of 0.003, 0.081, 0.260, 0.376, and 0.646 V for current densities of 10, 100, 500, 1 000, and 2 000 mA cm-2, respectively, and remarkable stability for 300 h, significantly outperforming those of previously reported OHzS systems and other chemicals-assisted hydrogen production systems. Theoretical calculations reveal that extraordinary performance of HEANFA for OHzS is attributed to its abundant high-activity sites and optimizable reaction pathways in HER and HzOR. In particular, HEANFA enables intelligent migration of key intermediates during HzOR, thereby optimizing the reaction pathways and creating high-activity sites, ultimately endowing the extraordinary performance for OHzS.

Enhancing Hydrogen Evolution Reaction through Coalescence-Induced Bubble Departure on Patterned Gold-Silicon Microstrip Surfaces

Hydrogen bubble adhesion to the electrode presents a major obstacle for green hydrogen generation via the hydrogen evolution reaction (HER) as it would induce undesired overpotential and undermine the reaction efficiency by reducing reaction area, increasing transport resistance, and creating an undesired ion concentration gradient. While electrodes with aerophobic/hydrophilic surfaces have been developed to facilitate bubble detachment, they primarily rely on micro- and nanostructured catalyst surfaces to enhance buoyance-induced bubble departure. Here, we demonstrate that introducing nonreactive yet more hydrophilic surfaces can promote coalescence-induced bubble departure, thereby significantly reducing the transport overpotential and improving HER performance. Through a systematic study using patterned gold-silicon microstrip (GSM) surfaces with varied gold strip widths (50-1600 μm), we found that reducing the gold strip width results in a smaller bubble departure diameter and increased bubble departure frequencies, leading to a 400 mV reduction in transport overpotential at 400 mA/cm2 on 50 μm wide GSM surfaces. These patterned surfaces demonstrated superior HER performance compared to a plain gold surface, even with a 50% reduction in the reaction area. The optimal HER performance, characterized by the lowest total overpotential, was achieved on GSM surfaces with 200 μm wide gold strips, highlighting the intricate interplay between improved bubble dynamics and reduced reaction area.

Edge-doped substituents as an emerging atomic-level strategy for enhancing M-N4-C single-atom catalysts in electrocatalysis of the ORR, OER, and HER

M-N4-C single-atom catalysts (MN4) have gained attention for their efficient use at the atomic level and adjustable properties in electrocatalytic reactions like the ORR, OER, and HER. Yet, understanding MN4's activity origin and enhancing its performance remains challenging. Edge-doped substituents profoundly affect MN4's activity, explored in this study by investigating their interaction with MN4 metal centers in ORR/OER/HER catalysis (Sub@MN4, Sub = B, N, O, S, CH3, NO2, NH2, OCH3, SO4; M = Fe, Co, Ni, Cu). The results show overpotential variations (0 V to 1.82 V) based on Sub and metal centers. S and SO4 groups optimize FeN4 for peak ORR activity (overpotential at 0.48 V) and reduce OER overpotentials for NiN4 (0.48 V and 0.44 V). N significantly reduces FeN4's HER overpotential (0.09 V). Correlation analysis highlights the metal center's key role, with ΔG*H and ΔG*OOH showing mutual predictability (R2 = 0.92). Eg proves a reliable predictor for Sub@CoN4 (ΔG*OOH/ΔG*H, R2 = 0.96 and 0.72). Machine learning with the KNN model aids catalyst performance prediction (R2 = 0.955 and 0.943 for ΔG*OOH/ΔG*H), emphasizing M-O/M-H and the d band center as crucial factors. This study elucidates edge-doped substituents' pivotal role in MN4 activity modulation, offering insights for electrocatalyst design and optimization.

Enhancing electrocatalytic hydrogen evolution via engineering unsaturated electronic structures in MoS2

The search for efficient, earth-abundant electrocatalysts for the hydrogen evolution reaction (HER) has identified unsaturated molybdenum disulfide (MoS2) as a leading candidate. This review synthesises recent advancements in the engineering of MoS2 to enhance its electrocatalytic properties. It focuses on strategies for designing an unsaturated electronic structure on metal catalytic centers and their role in boosting the efficiency of the hydrogen evolution reaction (HER). It also considers how to optimize the electronic structures of unsaturated MoS2 for enhanced catalytic performance. This review commences with an examination of the fundamental crystal structure of MoS2; it elucidates the classical unsaturated electron configurations and the intrinsic factors that contribute to such electronic structures. Furthermore, it introduces popular strategies for constructing unsaturated electronic structures at the atomic level, such as nanostructure engineering, surface chemical modification and interlayer coupling engineering. It also discusses the challenges and future research directions in the study of MoS2 electronic structures, with the aim of broadening their application in sustainable hydrogen production.

High Mass Transfer Rate in Electrocatalytic Hydrogen Evolution Achieved with Efficient Quasi-Gas Phase System

The adhesion of H2 bubbles on the electrode surface is one of the main factors limiting the performance of H2 evolution of electrolytic water, especially at high current density. To overcome this problem, here a "quasi-gas phase" electrolytic water reaction system based on capillary effect is proposed for the first time to improve the mass transfer efficiency of H2. The typical feature of this reaction system is that the main site of H2 evolution reaction is transferred from the bulk aqueous solution to the gas phase environment above the bulk aqueous solution, thus effectively inhibiting the aggregation of H2 bubbles and reducing the resistance of their diffusion away. Electrochemical test results show that the proposed quasi-gas phase system can significantly reduce the potential required in H2 evolution reaction process at high current density compared with the conventional electrolytic reaction system. Specifically, the overpotential potential is reduced by 0.31 V when the H2 evolution current density of 250 mA cm-2 is achieved.

Electrochemical In Situ Characterization Techniques in the Field of Energy Conversion

With the proposal of the "carbon peak and carbon neutrality" goals, the utilization of renewable energy sources such as solar energy, wind energy, and tidal energy has garnered increasing attention. Consequently, the development of corresponding energy conversion technologies has become a focal point. In this context, the demand for electrochemical in situ characterization techniques in the field of energy conversion is gradually increasing. Understanding the microscopic electrochemical reactions and their mechanisms in depth is a common concern shared by both academia and industry. Therefore, the development of electrochemical in situ characterization techniques holds critical significance. This paper comprehensively reviews electrochemical in situ characterization techniques in the field of energy conversion from three aspects: spectral characterization techniques of electrochemical reactions, characterization techniques for the spatial distribution of electrochemical reactions, and optical characterization techniques for the surface refractive index associated with the spatial distribution of electrochemical reactions. These characteristics are described in detail, and the future development direction of in situ characterization technology is prospected, with the aim of promoting the advancement of electrochemical in situ characterization technology in the field of energy conversion, facilitating energy transformation, and thus advancing the goals of "carbon peak and carbon neutrality."

Electrochemical exfoliation of graphite using aqueous ammonium hydrogen carbonate solution and the ability of the exfoliated product as a hydrogen production electrocatalyst support

Electrochemical exfoliation of graphite has attracted much attention as a practical mass production of two-dimensional graphene-like materials. There is an increasing desire to find new and improved methods to create unique exfoliated products with excellent functionality. We used aqueous ammonium hydrogen carbonate solution as a new electrolyte for anodic oxidative exfoliation of graphite. The exfoliated product has a porous two-dimensional structure, and it can be dispersed in water for over five years. The oxidized and defected porous surface serves as an ideal support for molecular metal complexes, effectively functioning as heterogeneous electrocatalysts for hydrogen production.

Ampere-Level Hydrogen Generation via 1000 H Stable Seawater Electrolysis Catalyzed by Pt-Cluster-Loaded NiFeCo Phosphide

Seawater electrolysis can generate carbon-neutral hydrogen but its efficiency is hindered by the low mass activity and poor stability of commercial catalysts at industrial current densities. Herein, Pt nanoclusters are loaded on nickel-iron-cobalt phosphide nanosheets, with the obtained Pt@NiFeCo-P electrocatalyst exhibiting excellent hydrogen evolution reaction (HER) activity and stability in alkaline seawater at ampere-level current densities. The catalyst delivers an ultralow HER overpotential of 19.7 mV at -10 mA cm-2 in seawater-simulating alkaline solutions, along with a Pt-mass activity 20.8 times higher than Pt/C under the same conditions, while dropping to 8.3 mV upon a five-fold NaCl concentrated natural seawater. Remarkably, Pt@NiFeCo-P offers stable operation for over 1000 h at 1 A cm-2 in an alkaline brine electrolyte, demonstrating its potential for efficient and long-term seawater electrolysis. X-ray photoelectron spectroscopy (XPS), in situ electrochemical impedance spectroscopy (EIS), and in situ Raman studies revealed fast electron and charge transfer from the NiFeCo-P substrate to Pt nanoclusters enabled by a strong metal-support interaction, which increased the coverage of H* and accelerated water dissociation on high valent Co sites. This study represents a significant advancement in the development of efficient and stable electrocatalysts with high mass activity for sustainable hydrogen generation from seawater.

Plasma Induced Atomic-Scale Soldering Enhanced Efficiency and Stability of Electrocatalysts for Ampere-Level Current Density Water Splitting

Industrial water electrolysis typically operates at high current densities, the efficiency and stability of catalysts are greatly influenced by mass transport processes and adhesion with substrates. The core scientific issues revolve around reducing transport overpotential losses and enhancing catalyst-substrate binding to ensure long-term performance. Herein, vertical Ni-Co-P is synthesized and employed plasma treatment for dual modification of its surface and interface with the substrate. The (N)Ni-Co-P/Ni3N cathode exhibits an ultra-low overpotential of 421 mV at 4000 mA cm-2, and the non-noble metal system only requires a voltage of 1.85 V to reach 1000 mA cm-2. When integrated into an anion exchange membrane (AEM) electrolyzer, it can operate stably for >300 h at 500 mA cm-2. Under natural light, the solar-driven AEM electrolyzer operates at a current density up to 1585 mA cm-2 with a solar-to-hydrogen efficiency (SHT) of 9.08%. Density functional theory (DFT) calculations reveal that plasma modification leads to an "atomic-scale soldering" effect, where the Ni3N strong coupling with the Co increases free charge density, simultaneously enhancing stability and conductivity. This research offers a promising avenue for optimizing ampere-level current density water splitting, paving the way for efficient and sustainable industrial hydrogen production.

Cell-Membrane-Inspired Ultrathin Silica Nanochannels Coating for Long-Term Stable Photoelectrocatalysis with Enhanced Performance

Photoelectrocatalysis has attracted significant attention for water splitting and contaminant degradation. However, the lifetime of photoelectrocatalysis devices is hampered by the severe instability and photocorrosion of the photo-active nanomaterial on the photoelectrode, which is a key limitation to realizing industrialization. Typically, the conventional protection strategy of photoelectrodes usually suffers from the trade-off between the photoelectrocatalytic activity and stability. Inspired by biological cell membrane with water channels, here a highly permeable and ultrathin silica coating with ultrasmall straight nanochannels is in situ grown that stabilizes the photoelectrode. These ultrasmall channels boost photoelectrocatalysis by accelerating water transport and reducing the reaction energy within the confined nanochannels. Specifically, the ultrathin coating imparts significant mechanical and structural stability to the photo-active nanomaterial, thereby preventing its detachment, dissolution, and crystal damage without compromising performance. As a result, the protected photoelectrode exhibits enhanced water splitting activity and excellent stability over 120 h, whereas the photocurrent of the unprotected photoelectrode degrades rapidly. Meanwhile, the coated photoelectrode also exhibits superior photoelectrocatalytic degradation efficiency (>97%), even after the 10th cycle. This strategy is facile and universal and can be extended to construct other stable and high-performance electrodes for promoting photoelectrocatalysis in practical applications.

Electronic Structure Regulation by Fe Doped Ni-Phosphides for Long-term Overall Water Splitting at Large Current Density

Acquiring a highly efficient electrocatalyst capable of sustaining prolonged operation under high current density is of paramount importance for the process of electrocatalytic water splitting. Herein, Fe-doped phosphide (Fe-Ni5P4) derived from the NiFc metal-organic framework (NiFc-MOF) (Fc: 1,1'-ferrocene dicarboxylate) shows high catalytic activity for overall water splitting (OWS). Fe-Ni5P4||Fe-Ni5P4 exhibits a low voltage of 1.72 V for OWS at 0.5 A cm-2 and permits stable operation for 2700 h in 1.0 m KOH. Remarkably, Fe-Ni5P4||Fe-Ni5P4 can sustain robust water splitting at an extra-large current density of 1 A cm-2 for 1170 h even in alkaline seawater. Theoretical calculations confirm that Fe doping simultaneously reduces the reaction barriers of coupling and desorption (O*→OOH*, OOH*→O2 *) in the oxygen evolution reaction (OER) and regulates the adsorption strength of the intermediates (H2O*, H*) in the hydrogen evolution reaction (HER), enabling Fe-Ni5P4 to possess excellent dual functional activity. This study offers a valuable reference for the advancement of highly durable electrocatalysts through the regulation derived from coordination frameworks, with significant implications for industrial applications and energy conversion technologies.

Magnetic Activation: A Novel Approach to Enhance Hydrogen Evolution Activity of Co0.85Se@CNTs Heterostructured Catalyst

The heterostructure strategy is currently an effective method for enhancing the catalytic activity of materials. However, the challenge that is how to further improve their catalytic performance, based on the principles of material modification is must addressed. Herein, a strategy is introduced for magnetically regulating the catalytic activity to further enhance the hydrogen evolution reaction (HER) activity for Co0.85Se@CNTs heterostructured catalyst. Building on heterostructure modulation, an external alternating magnetic field (AMF) is introduced to enhance the electronic localization at the active sites, which significantly boosts catalytic performance (71 to 43 mV at 10 mA cm-2). To elucidate the catalytic mechanism, especially under the influence of the AMF, in situ Raman spectroscopy is innovatively applied to monitor the HER process of Co0.85Se@CNTs, comparing conditions with and without the AMF. This study demonstrates that introducing the AMF does not induce a change in the true active site. Importantly, it shows that the Lorentz force generated by the AMF enhances HER activity by promoting water molecule adsorption and O─H bond cleavage, with the Stark tuning rate indicating increased water interaction and bond cleavage efficiency. Theoretical calculations further support that the AMF optimizes energy barriers for key reaction intermediates (steps of *H2O-TS and *H+*1/2H2).

Microenvironment Engineering of Heterogeneous Catalysts for Liquid-Phase Environmental Catalysis

Environmental catalysis has emerged as a scientific frontier in mitigating water pollution and advancing circular chemistry and reaction microenvironment significantly influences the catalytic performance and efficiency. This review delves into microenvironment engineering within liquid-phase environmental catalysis, categorizing microenvironments into four scales: atom/molecule-level modulation, nano/microscale-confined structures, interface and surface regulation, and external field effects. Each category is analyzed for its unique characteristics and merits, emphasizing its potential to significantly enhance catalytic efficiency and selectivity. Following this overview, we introduced recent advancements in advanced material and system design to promote liquid-phase environmental catalysis (e.g., water purification, transformation to value-added products, and green synthesis), leveraging state-of-the-art microenvironment engineering technologies. These discussions showcase microenvironment engineering was applied in different reactions to fine-tune catalytic regimes and improve the efficiency from both thermodynamics and kinetics perspectives. Lastly, we discussed the challenges and future directions in microenvironment engineering. This review underscores the potential of microenvironment engineering in intelligent materials and system design to drive the development of more effective and sustainable catalytic solutions to environmental decontamination.

Enhancing hydrogen evolution reaction activity through defects and strain engineering in monolayer MoS2

Molybdenum disulfide (MoS2) has recently emerged as a promising electrocatalyst for the hydrogen evolution reaction (HER). However, the poor in-plane electrical conductivity and inert basal plane activity pose major challenges in realizing its practical application. Herein, we demonstrate a new approach to induce biaxial strain into CVD-grown MoS2 monolayers by draping it over an array of patterned gold nanopillar arrays (AuNAs) as an efficient strategy to enhance its HER activity. We vary the magnitude of applied strain by changing the inter-pillar spacing, and its effect on the HER activity is investigated. To capitalize on the synergistic effect of improved ΔG H via strain engineering and leverage basal plane activation by introduction of sulphur vacancies, we further exposed the strained MoS2 monolayers to oxygen plasma treatment to create S-vacancies. The strained MoS2 on AuNAs with optimal inter-pillar spacing is exposed to oxygen plasma treatment for different durations, and we study its electrocatalytic activity towards the HER using on-chip microcell devices. The strained and vacancy-rich monolayer MoS2 draped on AuNAs with a 0.5 μm inter-pillar spacing and exposed to plasma for 50 s (S0.5μmV50-MoS2) is shown to exhibit remarkable improvement in HER activity, with an overpotential of 53 mV in 0.5 M H2SO4. Thus, the synergistic creation of additional vacancy defects, along with strain-induced active sites, results in enhancement in HER performance of CVD-grown monolayer MoS2. The present study provides a highly promising route for engineering 2D electrocatalysts towards efficient hydrogen evolution.

Unlocking Efficiency: Minimizing Energy Loss in Electrocatalysts for Water Splitting

Catalysts play a crucial role in water electrolysis by reducing the energy barriers for hydrogen and oxygen evolution reactions (HER and OER). Research aims to enhance the intrinsic activities of potential catalysts through material selection, microstructure design, and various engineering techniques. However, the energy consumption of catalysts has often been overlooked due to the intricate interplay among catalyst microstructure, dimensionality, catalyst-electrolyte-gas dynamics, surface chemistry, electron transport within electrodes, and electron transfer among electrode components. Efficient catalyst development for high-current-density applications is essential to meet the increasing demand for green hydrogen. This involves transforming catalysts with high intrinsic activities into electrodes capable of sustaining high current densities. This review focuses on current improvement strategies of mass exchange, charge transfer, and reducing electrode resistance to decrease energy consumption. It aims to bridge the gap between laboratory-developed, highly efficient catalysts and industrial applications regarding catalyst structural design, surface chemistry, and catalyst-electrode interplay, outlining the development roadmap of hierarchically structured electrode-based water electrolysis for minimizing energy loss in electrocatalysts for water splitting.

Recent Progress on Stability of Layered Double Hydroxide-Based Catalysts for Oxygen Evolution Reaction

Water electrolysis is regarded as one of the most viable technologies for the generation of green hydrogen. Nevertheless, the anodic oxygen evolution reaction (OER) constitutes a substantial obstacle to the large-scale deployment of this technology, due to the considerable overpotential resulting from the retardation kinetics associated with the OER. The development of low-cost, high-activity, and long-lasting OER catalysts has emerged as a pivotal research area. Layered double hydroxides (LDHs) have garnered significant attention due to their suitability for use with base metals, which are cost-effective and exhibit enhanced activity. However, the current performance of LDHs OER catalysts is still far from meeting the demands of industrial applications, particularly in terms of their long-term stability. In this review, we provide an overview of the causes for the deactivation of LDHs OER catalysts and present an analysis of the various mechanisms employed to improve the stability of these catalysts, including the synthesis of LDH ultrathin nanosheets, adjustment of components and doping, dissolution and redeposition, defect creation and corrosion, and utilization of advanced carbon materials.

Positively Charged Hollow Co Nanoshells by Kirkendall Effect Stabilized by Electron Sink for Alkaline Water Dissociation

While cobalt (Co) exhibits a comparable energy barrier for H* adsorption/desorption to platinum in theory, it is generally not suitable for alkaline hydrogen evolution reaction (HER) because of unfavorable water dissociation. Here, the Kirkendall effect is adopted to fabricate positive-charged hollow metal Co (PHCo) nanoshells that are stabilized by MoO2 and chainmail carbon as the electron sink. Compared to the zero-valent Co, the PHCo accelerates the water dissociation and changes the rate-determining step from Volmer to Heyrovsky process. Alkaline HER occurs with a low overpotential of 59.0 mV at 10 mA cm-2. Operando Raman and first principles calculations reveal that the interfacial water to the PHCo sites and the accelerated proton transfer are conducive to the adsorption and dissociation of H2O molecules. Meanwhile, the upshifted d-band center of PHCo optimizes the adsorption/desorption of H*. This work provides a unique synthesis of hollow Co nanoshells via the Kirkendall effect and insights to water dissociation on catalyst surfaces with tailored charge states.

Laser-Induced Controllable Porosity in Additive Manufacturing Boosts Efficiency of Electrocatalytic Water Splitting

In laser-based additive manufacturing (AM), porosity and unmelted metal powder are typically considered undesirable and harmful. Nevertheless in this work, precisely controlling laser parameters during printing can intentionally introduce controllable porosity, yielding a porous electrode with enhanced catalytic activity for the oxygen evolution reaction (OER). This study demonstrates that deliberate introduction of porosity, typically considered a defect, leads to improved gas molecule desorption, enhanced mass transfer, and increased catalytically active sites. The optimized P-93% electrode displays superior OER performance with an overpotential of 270 mV at 20 mA cm-2. Furthermore, it exhibits remarkable long-term stability, operating continuously for over 1000 h at 10 mA cm-2 and more than 500 h at 500 mA cm-2. This study not only provides a straightforward and mass-producible method for efficient, binder-free OER catalysts but also, if optimized, underscores the potential of laser-based AM driven defect engineering as a promising strategy for industrial water splitting.

A N-doped carbon substrate makes the Ru-Co alloy an efficient electrocatalyst for pH-universal seawater splitting

Designing electrocatalysts for seawater splitting remains challenging. A Ru-Co alloy supported by an N-doped carbon substrate catalyst has been designed using etching and a low-temperature treatment method. Studies show that the superior performance of this catalyst is related to the hollow-structured N-doped carbon frame and surface reconstruction of the Ru-Co alloy.

Flexible tungsten disulfide superstructure engineering for efficient alkaline hydrogen evolution in anion exchange membrane water electrolysers

Anion exchange membrane (AEM) water electrolysis employing non-precious metal electrocatalysts is a promising strategy for achieving sustainable hydrogen production. However, it still suffers from many challenges, including sluggish alkaline hydrogen evolution reaction (HER) kinetics, insufficient activity and limited lifetime of non-precious metal electrocatalysts for ampere-level-current-density alkaline HER. Here, we report an efficient alkaline HER strategy at industrial-level current density wherein a flexible WS2 superstructure is designed to serve as the cathode catalyst for AEM water electrolysis. The superstructure features bond-free van der Waals interaction among the low Young's modulus nanosheets to ensure excellent mechanical flexibility, as well as a stepped edge defect structure of nanosheets to realize high catalytic activity and a favorable reaction interface micro-environment. The unique flexible WS2 superstructure can effectively withstand the impact of high-density gas-liquid exchanges and facilitate mass transfer, endowing excellent long-term durability under industrial-scale current density. An AEM electrolyser containing this catalyst at the cathode exhibits a cell voltage of 1.70 V to deliver a constant catalytic current density of 1 A cm-2 over 1000 h with a negligible decay rate of 9.67 μV h-1.

Self-supported Ru-doped NiMoO4 for efficient hydrogen evolution with 1000 mA cm-2 at a low overpotential

Self-supported Ru-doped NiMoO4 (Ru-NiMoO4) is synthesized on commercial NiMo foam. The Ru-NiMoO4 exhibits extremely high performance for electrocatalytic hydrogen evolution with a small overpotential of 170.6 mV to afford a current density of 1000 mA cm-2, and excellent durability for 150 hours in alkaline solution.

Heterojunction-Induced Rapid Transformation of Ni3+/Ni2+ Sites which Mediates Urea Oxidation for Energy-Efficient Hydrogen Production

Water electrolysis is an environmentally-friendly strategy for hydrogen production but suffers from significant energy consumption. Substituting urea oxidation reaction (UOR) with lower theoretical voltage for water oxidation reaction adopting nickel-based electrocatalysts engenders reduced energy consumption for hydrogen production. The main obstacle remains strong interaction between accumulated Ni3+ and *COO in the conventional Ni3+-catalyzing pathway. Herein, a novel Ni3+/Ni2+ mediated pathway for UOR via constructing a heterojunction of nickel metaphosphate and nickel telluride (Ni2P4O12/NiTe), which efficiently lowers the energy barrier of UOR and avoids the accumulation of Ni3+ and excessive adsorption of *COO on the electrocatalysts, is developed. As a result, Ni2P4O12/NiTe demonstrates an exceptionally low potential of 1.313 V to achieve a current density of 10 mA cm-2 toward efficient urea oxidation reaction while simultaneously showcases an overpotential of merely 24 mV at 10 mA cm-2 for hydrogen evolution reaction. Constructing urea electrolysis electrolyzer using Ni2P4O12/NiTe at both sides attains 100 mA cm-2 at a low cell voltage of 1.475 V along with excellent stability over 500 h accompanied with nearly 100% Faradic efficiency.

Interlayer Biatomic Pair Bridging the van der Waals Gap for 100% Activation of 2D Layered Material

2D layered materials are regarded as prospective catalyst candidates due to their advantageous atomic exposure ratio. Nevertheless, the predominant population of atoms residing on the basal plane with saturated coordination, exhibit inert behavior, while a mere fraction of atoms located at the periphery display reactivity. Here, a novel approach is reported to attain complete atom activation in 2D layered materials through the construction of an interlayer biatomic pair bridge. The atoms in question have been strategically optimized to achieve a highly favorable state for the adsorption of intermediates. This optimization results from the introduction of new gap states around the Fermi level. Moreover, the presence of the interlayer bridge facilitates the electron transfer across the van der Waals gap, thereby enhancing the reaction kinetics. The hydrogen evolution reaction exhibits an impressive ultrahigh current density of 2000 mA cm-2 at 397 mV, surpassing the pristine MoS2 by approximately two orders of magnitude (26 mA cm-2 at 397 mV). This study provides new insights for enhancing the efficacy of 2D layered catalysts.

Bioinspired Gas Manipulation for Regulating Multiphase Interactions in Electrochemistry

The manipulation of gas in multiphase interactions plays a crucial role in various electrochemical processes. Inspired by nature, researchers have explored bioinspired strategies for regulating these interactions, leading to remarkable advancements in design, mechanism, and applications. This paper provides a comprehensive overview of bioinspired gas manipulation in electrochemistry. It traces the evolution of gas manipulation in gas-involving electrochemical reactions, highlighting the key milestones and breakthroughs achieved thus far. The paper then delves into the design principles and underlying mechanisms of superaerophobic and (super)aerophilic electrodes, as well as asymmetric electrodes. Furthermore, the applications of bioinspired gas manipulation in hydrogen evolution reaction (HER), carbon dioxide reduction reaction (CO2RR), and other gas-involving electrochemical reactions are summarized. The promising prospects and future directions in advancing multiphase interactions through gas manipulation are also discussed.

Dual interfacing with metallic cobalt boosts the electron shuttle of CdS-carbide nanoassemblies

Harnessing accelerated interfacial redox, thus boosting charge separation, is of great importance in photocatalytic solar hydrogen generation. In effect, nanoassembling non-noble metallic phases in CdS-based systems and elucidating their role in photocatalysis hold the key to eventually boosting electron shuttle in the field. Here we combine an efficient in-situ exsoluted metallic Co0 nanoparticles on a carbides matrix (CMG) with CdS (CdS@CoCMG) for photogeneration of hydrogen. The metallic cobalt phase exhibits strong binding at the CdS-carbide dual interfaces, forming the accelerated "electron converter" mechanism validated by charge transfer kinetics and achieving two orders of magnitude faster hydrogen production (44.42 mmol g-1 h-1) relative to CdS (0.43 mmol g-1 h-1). We propose that the unique catalyst configuration enable the directional electron-relay photocatalysis via harnessing interfaces between Co0 phase, carbides, and CdS clusters, which eventually boosts the redox process and charge separation of the integrated system, leading to high H2 production rates in the suspension.

Design Strategies towards Advanced Hydrogen Evolution Reaction Electrocatalysts at Large Current Densities

Hydrogen (H2), produced by water electrolysis with the electricity from renewable sources, is an ideal energy carrier for achieving a carbon-neutral and sustainable society. Hydrogen evolution reaction (HER) is the cathodic half-reaction of water electrolysis, which requires active and robust electrocatalysts to reduce the energy consumption for H2 generation. Despite numerous electrocatalysts have been reported by the academia for HER, most of them were only tested under relatively small current densities for a short period, which cannot meet the requirements for industrial water electrolysis. To bridge the gap between academia and industry, it is crucial to develop highly active HER electrocatalysts which can operate at large current densities for a long time. In this review, the mechanisms of HER in acidic and alkaline electrolytes are firstly introduced. Then, design strategies towards high-performance large-current-density HER electrocatalysts from five aspects including number of active sites, intrinsic activity of each site, charge transfer, mass transfer, and stability are discussed via featured examples. Finally, our own insights about the challenges and future opportunities in this emerging field are presented.

Stable hydrogen evolution reaction at high current densities via designing the Ni single atoms and Ru nanoparticles linked by carbon bridges

Continuous and effective hydrogen evolution under high current densities remains a challenge for water electrolysis owing to the rapid performance degradation under continuous large-current operation. In this study, theoretical calculations, operando Raman spectroscopy, and CO stripping experiments confirm that Ru nanocrystals have a high resistance against deactivation because of the synergistic adsorption of OH intermediates (OHad) on the Ru and single atoms. Based on this conceptual model, we design the Ni single atoms modifying ultra-small Ru nanoparticle with defect carbon bridging structure (UP-RuNiSAs/C) via a unique unipolar pulse electrodeposition (UPED) strategy. As a result, the UP-RuNiSAs/C is found capable of running steadily for 100 h at 3 A cm-2, and shows a low overpotential of 9 mV at a current density of 10 mA cm-2 under alkaline conditions. Moreover, the UP-RuNiSAs/C allows an anion exchange membrane (AEM) electrolyzer to operate stably at 1.95 Vcell for 250 h at 1 A cm-2.

Operando Spectroscopy Observation of Mo Clusters-Ti3 C2 TX Catalyst/Support Interface's Dynamic Evolution in Hydrogen Evolution Reaction

The interaction between catalyst and support plays an important role in electrocatalytic hydrogen evolution (HER), which may explain the improvement in performance by phase transition or structural remodeling. However, the intrinsic behavior of these catalysts (dynamic evolution of the interface under bias, structural/morphological transformation, stability) has not been clearly monitored, while the operando technology does well in capturing the dynamic changes in the reaction process in real time to determine the actual active site. In this paper, nitrogen-doped molybdenum atom-clusters on Ti3 C2 TX (MoACs /N-Ti3 C2 TX ) is used as a model catalyst to reveal the dynamic evolution of MoAcs on Ti3 C2 TX during the HER process. Operando X-ray absorption structure (XAS) theoretical calculation and in situ Raman spectroscopy showed that the Mo cluster structure evolves to a 6-coordinated monatomic Mo structure under working conditions, exposing more active sites and thus improving the catalytic performance. It shows excellent HER performance comparable to that of commercial Pt/C, including an overpotential of 60 mV at 10 mA cm-2 , a small Tafel slope (56 mV dec-1 ), and high activity and durability. This study provides a unique perspective for investigating the evolution of species, interfacial migration mechanisms, and sources of activity-enhancing compounds in the process of electroreduction.

Locally Strained 2D Materials: Preparation, Properties, and Applications

2D materials are promising for strain engineering due to their atomic thickness and exceptional mechanical properties. In particular, non-uniform and localized strain can be induced in 2D materials by generating out-of-plane deformations, resulting in novel phenomena and properties, as witnessed in recent years. Therefore, the locally strained 2D materials are of great value for both fundamental studies and practical applications. This review discusses techniques for introducing local strains to 2D materials, and their feasibility, advantages, and challenges. Then, the unique effects and properties that arise from local strain are explored. The representative applications based on locally strained 2D materials are illustrated, including memristor, single photon emitter, and photodetector. Finally, concluding remarks on the challenges and opportunities in the emerging field of locally strained 2D materials are provided.

Diluting the Resistance of Built-in Electric Fields in Oxygen Vacancy-enriched Ru/NiMoO4-x for Enhanced Hydrogen Spillover in Alkaline Seawater Splitting

Recently, hydrogen spillover based binary (HSBB) catalysts have received widespread attention due to the sufficiently utilized reaction sites. However, the specific regulation mechanism of spillover intensity is still unclear. Herein, we have fabricated oxygen vacancies enriched Ru/NiMoO4-x to investigate the internal relationship between electron supply and mechanism of hydrogen spillover enhancement. The DFT calculations cooperate with in situ Raman spectrum to uncover that the H* spillover from NiMoO4-x to Ru. Meanwhile, oxygen vacancies weakened the electron supply from Ru to NiMoO4-x , which contributes to dilute the resistance of built-in electric field (BEF) for hydrogen spillover. In addition, the higher ion concentration in electrolyte will promote the H* adsorption step obviously, which is demonstrated by in situ EIS tests. As a result, the Ru/NiMoO4-x exhibits a low overpotential of 206 mV at 3.0 A cm-2 , a small Tafel slope of 28.8 mV dec-1 , and an excellent durability of 550 h at the current density of 0.5 A cm-2 for HER in 1.0 M KOH seawater.

Te-doped-WSe2/W as a stable monolith catalyst for ampere-level current density hydrogen evolution reaction

The development of efficient electrocatalysts for the hydrogen evolution reaction (HER) holds immense importance in the context of large-scale hydrogen production from water. Nevertheless, the practical application of such catalysts still relies on precious platinum-based materials. There is a pressing need to design high-performing, non-precious metal electrocatalysts capable of generating hydrogen at substantial current levels. We report here a stable monolith catalyst of Te-doped-WSe2 directly supported by a highly conductive W mesh. This catalyst demonstrates outstanding electrocatalytic performance and stability in acidic electrolytes, especially under high current conditions, surpassing the capabilities of commercial 5% Pt/C catalysts. Specifically, at current densities of 10 and 1200 mA cm-2, it exhibits a minimal overpotential of 79 and 232 mV, along with a small Tafel slope of 55 mV dec-1, respectively. The remarkable catalytic activity of Te-WSe2 can be attributed to the exceptional electron transfer facilitated by the stable monolithic structure, as well as the abundant and efficient active sites in the material. In addition, density functional theory calculations further indicate that Te doping adjusts H atom adsorption on various positions of WSe2, making it closer to thermal neutrality compared to the original material. This study presents an innovative approach to develop cost-effective HER electrocatalysts that perform optimally under high current density conditions.

Enabling Ultrafine Ru Nanoparticles with Tunable Electronic Structures via a Double-Shell Hollow Interlayer Confinement Strategy toward Enhanced Hydrogen Evolution Reaction Performance

Engineering of the catalysts' structural stability and electronic structure could enable high-throughput H2 production over electrocatalytic water splitting. Herein, a double-shell interlayer confinement strategy is proposed to modulate the spatial position of Ru nanoparticles in hollow carbon nanoreactors for achieving tunable sizes and electronic structures toward enhanced H2 evolution. Specifically, the Ru can be anchored in either the inner layer (Ru-DSC-I) or the external shell (Ru-DSC-E) of double-shell nanoreactors, and the size of Ru is reduced from 2.2 to 0.9 nm because of the double-shell confinement effect. The electronic structures are efficiently optimized thereby stabilizing active sites and lowering the reaction barrier. According to finite element analysis results, the mesoscale mass diffusion can be promoted in the double-shell configuration. The Ru-DSC-I nanoreactor exhibits a much lower overpotential (η10 = 73.5 mV) and much higher stability (100 mA cm-2). Our work might shed light on the precise design of multishell catalysts with efficient refining electrostructures toward electrosynthesis applications.

Unlocking Catalytic Potential: Exploring the Impact of Thermal Treatment on Enhanced Electrocatalysis of Nanomaterials

In the evolving field of electrocatalysis, thermal treatment of nano-electrocatalysts has become an essential strategy for performance enhancement. This review systematically investigates the impact of various thermal treatments on the catalytic potential of nano-electrocatalysts. The focus encompasses an in-depth analysis of the changes induced in structural, morphological, and compositional properties, as well as alterations in electro-active surface area, surface chemistry, and crystal defects. By providing a comprehensive comparison of commonly used thermal techniques, such as annealing, calcination, sintering, pyrolysis, hydrothermal, and solvothermal methods, this review serves as a scientific guide for selecting the right thermal technique and favorable temperature to tailor the nano-electrocatalysts for optimal electrocatalysis. The resultant modifications in catalytic activity are explored across key electrochemical reactions such as electrochemical (bio)sensing, catalytic degradation, oxygen reduction reaction, hydrogen evolution reaction, overall water splitting, fuel cells, and carbon dioxide reduction reaction. Through a detailed examination of the underlying mechanisms and synergistic effects, this review contributes to a fundamental understanding of the role of thermal treatments in enhancing electrocatalytic properties. The insights provided offer a roadmap for future research aimed at optimizing the electrocatalytic performance of nanomaterials, fostering the development of next-generation sensors and energy conversion technologies.

Dynamically Adaptive Bubbling for Upgrading Oxygen Evolution Reaction Using Lamellar Fern-Like Alloy Aerogel Self-Standing Electrodes

Adopting renewable electricity to produce "green" hydrogen has been a critical challenge because at a high current density the mass transfer capability of most catalytic electrodes deteriorates significantly. Herein, a unique lamellar fern-like alloy aerogel (LFA) electrode, showing a unique dynamically adaptive bubbling capability and can effectively avoid stress concentration caused by bubble aggregation is reported. The LFA electrode is intrinsically highly catalytic-active and shows a highly porous, resilient, hierarchically ordered, and well-percolated conductive network. It not only shows superior gas evacuation capability but also exhibits significantly improved stability at high current densities, showing the record lowest oxygen evolution reaction (OER) overpotential of 244 mV at 1000 mA cm-2 and stably over 6000 h. With the merits of mechanical robustness, excellent electron transport, and efficient bubble evacuation, LFA can be self-standing catalytic electrode and gas diffusion layers in anion-exchange-membrane water electrolysis (AEMWE), which can achieve 3000 mA cm-2 at a low voltage of 1.88 V and can sustain stable electrolysis at 2000 mA cm-2 for over 1300 h. This strategy can be extended to various gas evolution reactions as a general design rule for multiphase catalysis applications.

Superhydrophilicity boron-doped cobalt phosphide nanosheets decorated carbon nanotube arrays self-supported electrode for overall water splitting

Transition metal borides (TMBs) or phosphides (TMPs) have attracted great attention to the design of bifunctional electrocatalysts for energy storage. The superaerophobicity and superhydrophilicity of the catalytic electrode surface are crucial factors to determine the reaction process of the gas electrode. Herein, we report a self-supported electrode of carbon nanotube (CNTs) array grown on carbon cloth (CC) modulated together by boron-doped cobalt phosphide (CoP-B/CNTs/CC). The electrode requires the overpotential of 73.8 mV and 189.5 mV at the current density of ±10 mA cm-2 for hydrogen and oxygen evolution reactions in an alkaline electrolyte (1.0 M KOH), respectively, meanwhile maintaining outstanding long-term durability for more than 300 h. The excellent activity of CoP-B/CNTs/CC is attributed to boron doping regulating its electronic structure and further enriching active sites. The attractive stability of CoP-B/CNTs/CC is due to the unique geometric structure of the self-supported electrode. Furthermore, the superaerophobicity and superhydrophilicity of the electrode surface also accelerate the reaction process of the gas electrode. Expectedly, water splitting cells assembled using CoP-B/CNTs/CC electrodes as cathode and anode, respectively, require a cell voltage of 1.54 V at 10 mA cm-2, which is lower than that of the Pt/C/CC||RuO2/CC couple (1.69 V at 10 mA cm-2). Importantly, CoP-B/CNTs/CC||CoP-B/CNTs/CC achieve stable cell voltage under the step current changes (10 mA cm-2, 50 mA cm-2, and 100 mA cm-2) over 300 h. This work highlights a new path to understanding the effects of the static and dynamic behavior of bubbles on the surface of self-supporting electrodes on catalytic performance.

Bubble Engineering on Micro-/Nanostructured Electrodes for Water Splitting

Bubble behaviors play crucial roles in mass transfer and energy efficiency in gas evolution reactions. Combining multiscale structures and surface chemical compositions, micro-/nanostructured electrodes have drawn increasing attention. With the aim to identify the exciting opportunities and rationalize the electrode designs, in this review, we present our current comprehension of bubble engineering on micro-/nanostructured electrodes, focusing on water splitting. We first provide a brief introduction of gas wettability on micro-/nanostructured electrodes. Then we discuss the advantages of micro-/nanostructured electrodes for mass transfer (detailing the lowered overpotential, promoted supply of electrolyte, and faster bubble growth kinetics), localized electric field intensity, and electrode stability. Following that, we outline strategies for promoting bubble detachment and directional transportation. Finally, we offer our perspectives on this emerging field for future research directions.

Recent Advances in Engineering of 2D Materials-Based Heterostructures for Electrochemical Energy Conversion

2D materials, such as graphene, transition metal dichalcogenides, black phosphorus, layered double hydroxides, and MXene, have exhibited broad application prospects in electrochemical energy conversion due to their unique structures and electronic properties. Recently, the engineering of heterostructures based on 2D materials, including 2D/0D, 2D/1D, 2D/2D, and 2D/3D, has shown the potential to produce synergistic and heterointerface effects, overcoming the inherent restrictions of 2D materials and thus elevating the electrocatalytic performance to the next level. In this review, recent studies are systematically summarized on heterostructures based on 2D materials for advanced electrochemical energy conversion, including water splitting, CO2 reduction reaction, N2 reduction reaction, etc. Additionally, preparation methods are introduced and novel properties of various types of heterostructures based on 2D materials are discussed. Furthermore, the reaction principles and intrinsic mechanisms behind the excellent performance of these heterostructures are evaluated. Finally, insights are provided into the challenges and perspectives regarding the future engineering of heterostructures based on 2D materials for further advancements in electrochemical energy conversion.

The Secret of Nanoarrays toward Efficient Electrochemical Water Splitting: A Vision of Self-Dynamic Electrolyte

Nanoarray electrocatalysts with unique advantage of facilitating gas bubble detachment have garnered significant interest in gas evolution reactions (GERs). Existing research is largely based on a static hypothesis, assuming that buoyancy is the only driving force for the release of bubbles during GERs. However, this hypothesis overlooks the effect of the self-dynamic electrolyte flow, which is induced by the release of mature bubbles and helps destabilize and release the smaller, immature bubbles nearby. Herein, the enhancing effect of self-dynamic electrolyte flow on nanoarray structures is examined. Phase-field simulations demonstrate that the flow field of electrode with arrayed surface focuses shear force directly onto the gas bubble for efficient detachment, due to the flow could pass through voids and channels to bypass the shielding effect. The flow field therefore has a more substantial impact on the arrayed surface than the nanoscale smooth surface in terms of reducing the critical bubble size. To validate this, superaerophobic ferrous-nickel sulfide nanoarrays are fabricated and employed for water splitting, which display improved efficiency for GERs. This study contributes to understanding the influence of self-dynamic electrolyte on GERs and emphasizes that it should be considered when designing and evaluating nanoarray electrocatalysts.