Among the current industrial hydrogen production technologies, electrolysis has attracted widespread attention due to its zero carbon emissions and sustainability. However, the existence of overpotential caused by reaction activation, mass/charge transfer, etc. makes the actual water splitting voltage higher than the theoretical value, severely limiting the industrial application of this technology. Therefore, it is particularly important to design and develop highly efficient electrocatalysts to reduce overpotential and improve energy efficiency. Among the various synthesis methods of electrocatalysts, electrochemical synthesis stands out due to its simplicity, easy reaction control, and low cost. This review article classifies and summarizes the electrochemical synthesis techniques (including electrodeposition, electrophoretic deposition, electrospinning, anodic oxidation, electrochemical intercalation, and electrochemical reconstruction), followed by their application in the field of water electrolysis. In addition, some challenges currently faced by electrochemical synthesis in electrocatalytic hydrogen production, and their potential solutions are discussed to promote the practical application of electrochemical synthesis in water electrolysis.

This review summarizes and classifies commonly used electrochemical synthesis techniques, followed by the application of electrochemical synthesis methods in research on water electrolysis. Additionally, some challenges faced by electrochemical synthesis in the field of water electrolysis and possible solutions are discussed.

Porous organic frameworks (POFs), including metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and hydrogen-bonded frameworks (HOFs), have become research and development hotspots in the field of metal-ion batteries (MIBs) because of their unique structures, variable pore sizes, high specific surface areas, abundant active sites and customizable frameworks. These natural advantages of POF materials provide sufficient conditions for high-performance electrode materials for MIBs. However, some POF-based materials are still in the early stages of development, and more efforts are needed to make them competitive in practical applications. This updated review provides a comprehensive overview of recent advancements in the application of POF-based materials for MIBs, including lithium-ion, sodium-ion, potassium-ion, zinc-ion, aluminum-ion and calcium-ion batteries. In addition, advanced characterization technologies and computational simulation techniques, including machine learning, are reviewed. The main challenges and prospects of the application of POF-based materials in MIBs are briefly discussed, which can provide insights into the design and synthesis of high-performance electrode materials.

This updated review provides a comprehensive overview of the recent advancements in the application of POF-based materials (MOFs, COFs, and HOFs) for metal-ion batteries (MIBs) including lithium-ion, sodium-ion, potassium-ion, zinc-ion, aluminum-ion and calcium-ion batteries. The advanced characterization technologies and computational simulation techniques including machine learning are reviewed. The main challenges and prospects of POF-based materials used in MIBs are discussed, providing insights into the design and synthesis of high-performance electrode materials.

The electrocatalytic oxidation reaction plays a key role in energy conversion and storage systems. In order to achieve the best energy efficiency and cost competitiveness in these systems, a comprehensive understanding of the strategic design of electrocatalysts and the underlying mechanisms is essential. Defect engineering, especially the incorporation of oxygen vacancies (OVs), has proven to be an effective electrocatalyst modification strategy. OVs can regulate the electronic structures of metal oxides and hydroxides, generate unsaturated coordination sites on the surfaces of catalysts, and act as active sites to significantly accelerate the rates of electrocatalytic reactions. In recent years, studies have shown that OVs play an important role in electrocatalytic oxidation reactions such as the oxidation of hydrocarbons, alcohols and amines. This review discusses the strategies for generating OV sites, advanced characterization techniques for identifying and analyzing OVs, and theoretical calculations to elucidate the underlying mechanisms. In addition, the application of OVs in the electrocatalytic process is particularly emphasized, which is crucial for elucidating the dynamic evolution of OVs in the reaction process and further promoting the design of efficient electrocatalytic systems. We believe that this paper will provide new ideas and ways to promote the development of new fields such as OV energy conversion and environmental protection.

Current battery research is primarily directed towards enhancing productivity optimization, reducing energy consumption, and improving battery performance, especially in addressing the hurdles of state-of-the-art battery production. The achievement of batteries with simultaneous high safety and energy density relies on the advancement of all-solid-state batteries utilizing robust solid electrodes and thin solid electrolytes. To achieve this, different electrode manufacturing processes from conventional techniques are required. Dry-electrode technology is an innovative concept and technique that enables the manufacture of electrodes through a "powder-film" route without the use of solvents. Dry-electrode technology can simplify manufacturing processes, restructure electrode microstructures, and enhance material compatibility. This review summarizes the concept and advantages of dry-electrode technology and discusses various efforts towards performance and efficiency enhancement. Dry-electrode technology is expected to contribute to the production capability of the next-generation battery industry with improved stability and energy density, promising a sustainable future.

Proton exchange membrane (PEM) fuel cells play a pivotal role in a sustainable society through the direct conversion of hydrogen energy to electricity. Porous electrode materials, including porous media flow fields, gas diffusion layers, microporous layers, and catalyst layers, are essential for fuel cell operation, efficiency, and durability, in which complex multiphysics transport (e.g., hydrogen/oxygen transport, electron/proton conduction, heat transfer, and liquid water flow) and electrochemical reactions (e.g., the oxygen reduction reaction at the cathode and the hydrogen oxidation reaction at the anode) occur, as revealed by both experiments and multiphysics modeling. In recent years, artificial intelligence (AI) has demonstrated significant efficacy in the research and development (R&D) of electrode materials. Artificial neural networks (ANNs), convolutional neural networks (CNNs), deep neural networks (DNNs), generative adversarial neural networks (GANs), support vector machines (SVMs), and genetic algorithms (GAs) have been applied to design and optimize porous structures, compositions, materials, and surface properties for PEM fuel cells, demonstrating reliable and fast optimization and prediction capabilities. This article reviews the main physics and explores AI to advance porous electrode design for PEM fuel cells. Unlike traditional experimental and simulation-based approaches, AI provides superior computational efficiency, enabling faster and more cost-effective exploration of complex design parameters. In the end, future R&D directions for next-generation highly effective electrodes are discussed.

A carbon semi-tube (CST) is a novel carbon morphology and represents one of the most advanced carbon materials in the field of nanotechnology. Its discovery has enriched the carbon material family. The successful development of semi-tubular non/low noble metal electrocatalysts for the oxygen reduction reaction (ORR), hydrogen oxidation reaction (HOR), hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and electrochemical carbon dioxide reduction reaction (CO₂RR) can provide very promising insights into the future uses of CST in many electrochemical energy technologies, such as fuel cells, batteries, supercapacitors, water electrolysis, and CO₂-electrolysis. Its unique nanostructure has many notable properties, including semi-tubular morphology, high degree of openness, adjustable curvature, large specific surface area, abundant pores, good electronic/ionic conductivity, and an ordered structure. This new material is expected to have many applications, especially in the area of electrochemical energy storage and conversion.

A carbon semi-tube (CST) with a novel semi-tubular morphology has been developed to supplement the carbon material family. This perspective introduces the progress of advanced carbon nanostructures, the success of CST-based non/low noble metal (platinum) catalysts for electrocatalysis, and the merits of CST for electrochemical technologies for electricity energy storage and conversion.

To improve the energy density and address the safety concerns of current lithium-ion batteries, garnet-based solid-state lithium metal batteries (GSSLBs) have drawn attention as candidates for next-generation electrochemical energy storage devices. Battery resistance, energy density and cycling capability are three fundamental indicators of GSSLBs and greatly influence their real applications. The progress toward developing low resistance, high energy density and improved cycling capability is reviewed in this paper based on an aim-oriented thinking. The fundamental effects of improving the ionic conductivity of garnet solid-state electrolytes (GSSEs) and engineering cathode/anode interfaces are first discussed. The significance of thinning GSSEs, decreasing the lithium metal anode level and exploiting high-energy cathodes for energy density is highlighted with the help of energy density estimation models. The benefits of and inspiration from constructing a three-dimensional (3D) configuration anode interface, applying external stack pressure and extending the operating temperature range to further improve the cycling capability of GSSLBs are also summarized. Moreover, the remaining challenges and future perspectives are presented with the expectation that our insights into the fundamentals and regular patterns can provide good guidance for developing better GSSLBs.

Solid-state batteries (SSBs) have emerged as a promising alternative technology for advancing global electrification efforts. The SSBs offer significant advantages over conventional electrolyte-based batteries, including enhanced safety, increased energy density, and improved performance. Their non-flammability, enhanced thermal and mechanical stability, and lower self-discharge rates make them particularly promising for future energy solutions. However, their prevalent implementation in large-scale industries is inhibited by inadequate ionic conductivity and the interfacial challenges associated with solid-state electrolytes (SSEs). These challenges include suboptimal solid–solid contact, grain boundary limitations, poor wettability, and unfavorable phenomena such as dendrite growth, interface voids, interdiffusion layer formation, and lattice mismatch. This comprehensive review meticulously examines recent developments and prospects in SSEs, categorizing them into halide, sulfide, oxide, hydride, and polymer types. It then analyzes the challenges and interfacial limitations of SSBs, including dendrite growth, voids, cracks, contact issues, lattice mismatch, and interdiffusion. In addition, potential solutions for enhancing interfacial adherence between electrodes and SSEs are outlined. Furthermore, recent trends in the SSB industry, including successfully commercialized products, are highlighted. Finally, this review explores the future potential of SSEs in advanced SSBs, projecting their significant industrial impact.

The widespread use of high-energy–density lithium-ion batteries (LIBs) in new energy vehicles and large-scale energy storage systems has intensified safety concerns, especially regarding the safe and reliable operation of large battery packs composed of hundreds of individual cells. This review begins with an analysis of the causes and failure mechanisms, and then continues with an examination of the many connections and influences among different factors to elucidate the complex and unpredictable issues of LIB safety. The analysis includes examples of large-scale battery failures to illustrate how failures propagate within extensive battery networks, highlighting the unique challenges associated with monitoring the safety of large-scale battery packs. Subsequently, a comparative assessment of numerous detection technologies is further conducted to underscore the challenges encountered in battery safety detection, particularly in large-scale battery systems. Additionally, the paper discusses the role of artificial intelligence (AI) in addressing battery safety concerns, explores the future trajectory of safety detection technology, and outlines the necessity and foundational framework for constructing smart battery management systems (BMSs). The discussion focuses on how AI and smart BMSs can be tailored to manage the complexities of large-scale battery packs, enabling real-time monitoring and predictive maintenance to prevent catastrophic failures.

To implement global energy transitions, the efficient utilization of clean energy plays a central role in the process and has become an imperative task. Among various approaches, solid oxide electrolysis cells (SOECs) stand out as exceptional energy conversion devices because of their ability to transform thermal and electrical energy into chemical energy. For example, solar energy is a clean and renewable energy source and can be effectively harnessed to power SOECs, thereby facilitating efficient conversion from solar to chemical energy. In light of the growing interest in leveraging SOECs for solar energy conversion, a systematic collation and comprehensive review of the relevant studies reported thus far have yet to be conducted. This review summarizes and analyzes recent advances in the field of SOECs, including their fundamentals, performance metrics, current status, and methods of integration with solar energy. It also proposes various optimization strategies for the existing integration of solar energy with SOEC systems, with a specific emphasis on full-spectrum utilization. Finally, this study provides a perspective on the future development and challenges for SOECs in the context of solar energy conversion.

An extensive literature review was conducted to investigate the pathways for the decarbonization and electrification of society and to cover different aspects to fulfill this objective. Despite the significant attraction and critical demand for achieving net-zero emissions, challenges must be addressed by adjusting policies and regulations and setting investments and budgets with the contribution of all nations and individuals. In this study, we explored the mission and vision of electrification, the reduction of greenhouse gas emissions, the mitigation of global warming, and net-zero targets. We considered alternative scenarios and the COP28 outputs from near-term (2025–2030) and long-term strategies. With this objective in mind, we focused on the clean energy transition as the primary step for electrification. In the following section, we thoroughly reviewed the supplies and capacities of renewables, as well as projected and planned investments, with particular emphasis on hydropower, hydrogen, and other sources. The material demand, which is the main challenge hindering the on-time deployment of clean energy, was investigated. With increasing reliance on renewables, energy storage balances generation and consumption, particularly during peak hours and high-demand situations. Batteries, fuel cells, supercapacitors, and coupled energy conversion and storage were extensively discussed as the main storage devices in electric and hybrid energy storage systems. Finally, we investigated the electrification potential in daily life, from transportation via light- or heavy-duty vehicles to electric aviation, electronic devices, buildings, industrial processes, and smart grids. This framework comprehensively assesses and reviews recently employed strategies for electrification to ensure sustainability and reliability over the coming years.

Organic electrode materials (OEMs) with cost-effectiveness, environment friendliness, tunable composition, structure diversity, and versatile functionalities can provide a great scope for the development of alkali metal-ion batteries (AMIBs) including lithium-, sodium-, and potassium-ion batteries. However, their high solubility in liquid organic electrolytes, low intrinsic conductivities, limited reversible capacities, and poor rate/cycling performance present significant obstacles to achieving widespread applications. To improve the practical performance of OEMs in AMIBs, numerous endeavors have been conducted in recent years, and great advances have been achieved. In this paper, the recent progress of OEMs in AMIBs is systematically reviewed in terms of their synthesis, characterization, functional mechanisms, and performance validation. The technical challenges are analyzed, and the perspectives and future research directions are proposed for overcoming the challenges toward the practical application of alkali metal-ion batteries.

Lithium-ion batteries have revolutionized energy storage, yet advanced technologies such as electric vehicles and eVTOLs demand even higher performance and safety. Anodes, the negative electrodes, are crucial in enhancing batteries’ safety, lifespan, and fast-charging capabilities. This review paper comprehensively evaluates the progression of anode materials from traditional graphite to advanced anodes like lithium metal. Graphite anodes, with a capacity of 372 mAh g⁻¹, enabled the first commercial lithium-ion batteries, but future applications require higher energy densities and fast-charging capabilities. Emerging anode materials, including alloying, and conversion types, as well as lithium metal, offer significantly higher capacities, with lithium metal offering a theoretical capacity of 3 860 mAh g⁻¹. However, these advanced anodes face challenges such as volume expansion, high surface reactivity, sluggish Li⁺ kinetics, and unstable lithium deposition morphologies. This review critically examines the electrochemical performance, interfacial properties, mechanical attributes, and stability issues of various anode materials. It further discusses solid electrolyte interphase (SEI) formation, strategies for enhancing interface stability, and the requirements of anodes for solid-state batteries. Additionally, the review explores potential solutions for limitations with each anode type, highlights innovative anode-free architectures, and evaluates the current and future trends of battery anode industries. Ultimately, this paper aims to guide the development of high-performance anode materials, paving the way for the next generation of efficient, reliable lithium batteries.

Aluminum-sulfur (Al-S) batteries have emerged as promising contenders in high-energy battery systems, have attracted significant research interest over the past decade because of their distinctive attributes, such as high capacity, high energy density, abundance, enhanced safety, and cost effectiveness, and have been rapidly developed. However, this novel energy conversion system still faces considerable challenges fundamentally attributed to the sluggish conversion kinetics induced by the inherent high charge density of Al³⁺ and to the severe shuttle effect. Increasing numbers of targeted strategies have significantly alleviated these issues. Nevertheless, an in-depth understanding and a systematic review to guide the enhancement of Al-S batteries are lacking. Hence, in this review, we first demonstrate the foundations of Al-S batteries, including their development history, fundamentals, crucial issues, and design principles. Subsequently, we present a comprehensive understanding and a discussion of the current strategies for different battery configurations. Finally, we offer some insights into crucial challenges and prospective solutions according to current developments, shedding some light on the future development of Al-S batteries.

Aluminum-sulfur (Al-S) batteries are considered excellent candidates for future largescaleenergy storage technology because of their high capacity, high energy density,high safety, and low cost. This article reviews the key issues and challenges for Al-Sbatteries, providing a comprehensive summary and an analysis of the developmentstrategies for each battery component. Finally, this article offers practical strategies fordeveloping future high-performance conversion-type Al-S batteries, consideringopportunities and directions for their development.103

In the context of the global greenhouse effect and energy scarcity, it is of great significance to convert carbon dioxide (CO₂) into value-added fuels and chemicals through renewable electricity. Cu-based catalysts have been challenging for producing C₁ and C₂₊ high-value chemicals in electrochemical CO₂ reduction reaction (CO₂RR). Plenty of research groups have engaged in the development of Cu-based catalysts with high activity, selectivity, and stability. This review comprehensively summarizes the recent progress in engineering Cu-based catalysts for CO₂RR, with a detailed understanding of the reaction mechanism, catalyst design, and product selectivity. Besides, the strategies aiming at improving the stability of Cu-based catalysts and advancements in CO₂RR electrolyzers are addressed. Finally, the future important research directions of Cu-based catalysts in practical CO₂RR are prospected.

Owing to their unique electronic structures and metallic-like properties, transition metal borides (TMBs) have demonstrated activity and stability that surpass those of traditional catalysts in the hydrogen evolution reaction (HER) of water splitting, becoming a research focus in the energy materials field. However, existing research generally lacks a systematic decoupling of the multidimensional correlation mechanisms of synthetic methods, structural regulation, and performance optimisation, severely restricting the rational design process of TMB catalysts. The aim of this review is to provide a cross-scale design paradigm for the development of high-performance TMB-based HER electrocatalysts by constructing a three-in-one analytical framework of theoretical guidance, synthetic innovation, and mechanism analysis. First, based on a fundamental understanding of the HER mechanism and d-band theory, we propose core principles for designing efficient catalysts. We review various synthetic methods, from traditional methods to innovative methods, and discuss their impact on catalytic performance. Through an in-depth analysis of the correlation between synthetic parameters and HER activity, valuable insights are provided for researchers seeking to optimise TMB-based electrocatalysts. Finally, this review highlights the current challenges and outlines future directions, emphasising the immense potential of TMB-based electrocatalysts in advancing sustainable hydrogen production.

Proton exchange membrane water electrolyzers (PEMWEs) are a promising technology for large-scale hydrogen production, yet their industrial deployment is hindered by the harsh acidic conditions and sluggish oxygen evolution reaction (OER) kinetics. This review provides a comprehensive analysis of recent advances in iridium-based electrocatalysts (IBEs), emphasizing novel optimization strategies to enhance both catalytic activity and durability. Specifically, we critically examine the mechanistic insights into OER under acidic conditions, revealing key degradation pathways of Ir species. We further highlight innovative approaches for IBE design, including (i) morphology and support engineering to improve stability, (ii) structure and phase modulation to enhance catalytic efficiency, and (iii) electronic structure tuning for optimizing interactions with reaction intermediates. Additionally, we assess emerging electrode engineering strategies and explore the potential of non-precious metal-based alternatives. Finally, we propose future research directions, focusing on rational catalyst design, mechanistic clarity, and scalable fabrication for industrial applications. By integrating these insights, this review provides a strategic framework for advancing PEMWE technology through highly efficient and durable OER catalysts.

In order to realize the efficient application of the industrial PEMWEs, material design strategies for stimulating the activity and stability capability of OER electrocatalysts are summarized, including (i) morphology/support effects, (ii) structure/phase engineering, (iii) electronic configuration/interaction. Furthermore, the reaction mechanism is deeply clarified, and electrode engineering and challenges of IBEs in practical PEMWE application are focused.

In this new era of energy, a tendency to increase the power density and capacity of advanced rechargeable batteries is urgently needed. With research on metal-ion (Li⁺, Na⁺, K⁺, Zn²⁺, Mg²⁺, and Al³⁺) batteries based on and beyond rocking-chair mechanism development, more attention has been given to modification of electrode materials. Layered materials, along with their two-dimensional (2D) analogs, show remarkable superiority in ion-intercalation chemistry and modification feasibility. In this context, extensive experimental and theoretical studies have been conducted in the design of interlayer nanoarchitectures to optimize their electrochemical performance. This review provides a comprehensive summary of the modification strategies for the interlayer nanostructure of layered materials, reveals the relationships between the inserted species and electrochemical performance, and offers guidance on the modification parameters for various metal-ion batteries. Finally, an outlook of the application potential, future research directions, and remaining challenges is provided. Overall, this review underscores the importance of material modification in achieving high-power density and high-capacity electrodes for batteries, paving the way for significant advancements in energy storage technology.

The Ni-rich layered cathode materials LiNi_xCo_yMn_1−x−yO₂ (NCM), which have a high energy density, are crucial in the strategic formulation of next-generation high-performance lithium-ion batteries (LIBs), particularly for cathode materials with Ni ⩾ 0.9. Although advances in NCM cathodes have made them competitive in terms of capacity and cost, persistent challenges such as surface chemical instability (electrolyte-driven surface degradation) and poor mechanical integrity (lattice oxygen evolution and anisotropic microcracking) of the cathodes remain. Addressing these limitations requires coordinated strategies spanning from atomic-level dopant engineering to macroscopic electrode architectural innovations to enable viable large-scale deployment. Extensive research has been conducted on the structural instability caused by an increase in the Ni content, but a comprehensive understanding of its underlying mechanisms and effective modification strategies for next-generation nickel-rich cathodes is lacking. Hence, we provide a thorough overview of the latest findings on microstructural degradation mechanisms in Ni-rich cathodes, delve into recent effective modification strategies and cutting-edge characterization methods, and finally, examine future research directions and limitations. This review elucidates the challenges facing ultrahigh-nickel cathodes and offers new insights into promising research avenues.

Attaining both high performance and long-term durability remains a critical yet challenging objective for low-Pt proton-exchange membrane fuel cells (PEMFCs). The carbon support on which catalysts and ionomers are dispersed strongly affects the cell performance by influencing the Pt activity, mass transport, and degradation. Currently, porous carbons endowed with a high surface area and internally embedded Pt particles are gaining prominence as promising support materials for low-Pt PEMFCs owing to their exceptional catalyst dispersion and kinetic activity. However, challenges in terms of unclear triple-phase boundaries, poor mass transport, and insufficient durability hinder their widespread implementation. Thus, this review provides a comprehensive understanding of and advanced guidelines for the exploration of porous carbons in low-Pt PEMFCs. We begin by analyzing the structures and morphologies of porous carbon catalysts to obtain an overview of their pore structures, Pt deposition, ionomer distribution, and water condensation. We subsequently summarize the mass transport mechanisms involved, exploring state-of-the-art strategies for improving mass transport through engineering accessible pore structures, tailoring uniform ionomer distributions, and incorporating well-defined ionic liquids, among other approaches. Furthermore, we highlight the effects of catalysts and porous carbon degradation on performance loss and introduce recent approaches to mitigate performance loss. Finally, we present conclusions along with outlooks on future exploration priorities. This extensive analysis of current challenges and advances in porous carbon supports is offered to inspire innovative ideas and technologies for the development of next-generation carbon supports for low-Pt PEMFCs.

As a key component of the proton exchange membrane water electrolyzer (PEMWE), the porous transport layer (PTL) not only provides mechanical support but also facilitates the supply of reactants to the electrode and the removal of produced gases and ensures efficient electrical and thermal management. Commercially available PTLs are often repurposed for other applications, such as filtration, and are not specifically tailored for PEMWE applications. Given this context, research output on PTL development has increased notably in recent years. Optimized, structured PTLs with preferred properties require applicable, relevant, and convenient diagnostic tools for PTL material development. As such, this work aims to identify and review a wide range of techniques for evaluating developed PTLs, including electrochemical techniques, custom-engineered cells, operando diagnosis, ex situ characterization, and postmortem analysis. By providing detailed information on these characterization techniques, this review aims to catalyze further research and development in the academic and industrial sectors, enhancing the understanding, development, and quality control of PTL components.

Productive and economical electrocatalysts for the oxygen evolution reaction (OER) are vital for reducing green hydrogen production costs and advancing the adoption of proton exchange membrane water electrolysis (PEMWE). However, the OER at the PEMWE anode involves complex proton-coupled electron transfer processes, leading to slow kinetics that limits electrolysis efficiency. Moreover, most OER catalysts are highly prone to corrosion in acidic solutions, challenging the long-term stable operation of PEMWE. Currently, OER catalysts rely heavily on iridium-based materials, which are expensive and scarce, hindering large-scale commercialization. Ruthenium, a less expensive platinum group metal, shows promising acidic OER activity but requires improved stability. Therefore, novel ruthenium-based OER catalysts are urgently needed. To achieve these goals, a thorough understanding of the acidic OER mechanisms, clear methods for material design, and the establishment of dependable performance evaluation metrics are necessary. In this review, we systematically summarize the extensively accepted mechanisms for acidic OER activity expression, which include the adsorption‒desorption mechanism, multi-active centre mechanism, and lattice oxygen oxidation mechanism, to guide the microstructural design of catalysts. Additionally, we introduce commonly used indicators for evaluating catalytic activity, aiming to provide a basis for catalyst screening. We subsequently discuss and review several types of recently reported Ru-based OER catalysts, namely, Ru metals, Ru alloys, and Ru-based oxide catalysts, with a focus on how their performance can be regulated and the potential structure‒performance relationships. Finally, we summarize some important issues that need attention in future research in this field to promote further study of Ru-based acidic oxidation catalysts.

Ru-based catalysts for oxygen evolution in acidic media: mechanism and strategies for breaking the activity and stability bottlenecks

Lithium-ion batteries (LIBs) are an indispensable component of the green revolution, and the growing demand for LIBs reflects this trend. As reliance on LIBs increases, sustainable metal recovery strategies are crucial to mitigating raw material scarcity and environmental concerns. This study examines commonly used and emerging lixiviants for metals extraction, balancing operational efficiency with environmental sustainability. Established mineral acids such as hydrochloric, sulfuric, and nitric acids are effective but pose ecological risks. On the other hand, organic acids present a promising alternative by reducing environmental impact but often compromising process efficiency. In addition to extensively studied organic acids, this review explores the potential of lesser-explored organic acid variants such as propionic and gluconic acids. Biometallurgical recovery, a hybridized alternative methodology to conventional hydrometallurgy, and electrochemical leaching, an emerging metal recovery method, are also explored to enhance sustainability. Furthermore, the review highlights the critical role of policy and regulatory frameworks in aligning recycling practices with circular economy principles and examines spent LIB recycling in China, the USA, and the European Union in this context. By exploring past and future trends, this work underscores the need for innovative, cost-effective, and environmentally responsible solutions in metallurgical processing.

Single-atom catalysts (SACs) exhibit tremendous potential in electrocatalysis because of their high intrinsic activity and remarkable selectivity arising from their tunable electronic structures and maximal atom utilization. A high density of SACs is fundamental for enhancing the activity and durability during electrochemical reactions. In this review, we first summarize the leading strategies for the synthesis of metal single-atom electrocatalysts and the use of machine learning in the design and screening of SACs, with a focus on maximizing the metal loading through deliberate temperature control, followed by the application of such high-loading SACs to a range of important reactions in electrochemical energy technologies, such as the oxygen reduction reaction (ORR), H₂O₂ electrosynthesis, the oxygen evolution reaction (OER), the hydrogen evolution reaction (HER), the carbon dioxide reduction reaction (CO₂RR), the nitrate reduction reaction (NO₃RR), and the reactions in lithium-sulfur batteries. The review concludes with a perspective highlighting the key challenges and future research directions in the development and application of high-density SACs.

High-density metal sites are crucial for enhancing the performance of single-atom catalysts (SACs) during electrocatalytic reactions. This review systematically summarizes the principal synthesis strategies for high-density SACs, outlines the application of machine learning-assisted designing and screening SACs, and discusses their applications in electrocatalytic energy storage and conversion systems.

High-capacity silicon (Si) is a promising material for manufacturing high-energy-density lithium-ion batteries. However, its practical applicability is severely restricted by the rapid degradation in its cycle life and calendar life. Within the context of the established understanding, Si failures are typically attributed primarily to the notable volume expansion effects of this material. However, the crucial role of chemical corrosion (e.g., hydrofluoric acid-driven corrosion) is frequently underestimated, despite its significant impact on the stability of both Si itself and the solid electrolyte interphase. In this review, the mechanisms of corrosion-induced Si degradation and the limitations of the existing mitigation strategies are systematically examined. More importantly, a novel perspective is proposed, thereby emphasizing galvanic corrosion driven by cathode oxidants, transition metal ion dissolution, and carbon additives, as well as chemical–mechanical coupling failures induced by Si corrosion. Finally, we advocate for the use of advanced characterization techniques, theoretical simulations, and holistic approaches integrating cathode design, auxiliary material optimization, and electrolyte engineering to address coupled chemical–mechanical failures for advancing the practical deployment of Si-based batteries.

The pursuit of high-energy–density fluoride-ion batteries (FIBs) has been considerably accelerated by the escalating demand for energy storage solutions outperforming existing lithium-ion technologies. As a promising alternative, FIBs leverage fluorine—the most electronegative element—to attain exceptional electrode potentials and energy densities. A comprehensive understanding of the chemistry underlying FIBs is therefore of paramount importance. To this end, this review provides an in-depth examination of the advancements in FIB development, covering cathode materials, anode materials, and electrolytes. Special emphasis is placed on summarizing the types and electrochemical properties of electrode materials. The review concludes with a forward-looking perspective, addressing practical challenges facing FIBs, the future development of electrode and electrolyte materials, advanced in situ characterization techniques, battery reaction mechanisms, and the potential of big data-enabled machine learning (ML). This manuscript seeks to deliver a detailed review of critical areas pivotal to advancing FIB technology, delineating the scope and contributions of this work to furnish theoretical guidance and insights into future trends in the field.

The development of low-cost and highly efficient electrocatalysts is crucial for the widespread adoption of clean energy technologies. Single-atom catalysts (SACs) have attracted extensive attention because of their exceptional catalytic performance and metal utilization. However, conventional methods for synthesizing SACs often have disadvantages such as an extremely low degree of metal loading and limited yield. Therefore, techniques for the scalable fabrication of SACs with high degrees of metal loading for use in practical applications are strongly needed. In this review, we first explore various design strategies for synthesizing stable SACs. Afterward, we highlight recent advances in improving the mass activity of SACs with high degrees of metal loading and introduce a universal strategy for synthesizing SACs on various supports. Furthermore, we provide a summary of facile strategies for the large-scale preparation of SACs for various electrocatalytic applications, including the oxygen reduction reaction, oxygen evolution reaction, hydrogen evolution reaction, and CO₂ reduction reaction. Finally, we discuss the challenges and perspectives of the large-scale production of SACs for use in practical applications. This review offers valuable guidance for the design of high-loading SACs.

The exploration of nanoscale high-entropy intermetallic compounds (HEICs) represents a transformative frontier in materials science, particularly in catalysis. The unique combination of multi-element composition, long-range atomic ordering, and nanoscale dimensions endows HEICs with superior electronic, structural, and catalytic properties that surpass those of traditional metal catalysts. However, achieving both uniform multi-element mixing and long-range ordered structures at the nanoscale is challenging. Building on this, this review highlights the key role of configurational entropy, mixing enthalpy, elemental composition, and size effects in the stable formation of nanoscale HEICs through thermodynamic and kinetic analysis. The latest advancements and existing challenges in the design, synthesis, structure, and applications of HEIC catalysts are discussed, with a focus on exploring their synthesis–structure–performance relationships from multiple perspectives. We hope that this review will offer valuable insights for further exploration and development of HEICs in catalytic applications.

Aqueous zinc-ion batteries (AZIBs) are promising to be widely used in large-scale energy storage devices due to their low cost, safety, and environmental friendliness. However, side reactions, including dendrite growth, anode corrosion, and electrode passivation, caused by uneven zinc deposition hinder further practical applications of AZIBs. Constructing artificial interfacial layers (AILs) is an effective strategy to stabilize zinc anodes, which has received significant attention. Herein, this review summarizes the basic principles, design strategies, and electrochemical performances of the AILs for Zn²⁺ ions. First, the side reactions on Zn anodes and their electrochemical mechanisms are briefly discussed. The classification, components, structural features, synthetic methods, and electrochemical mechanisms of the AILs are then combed in detail with a focus on the interaction between Zn anodes and AILs based on underlying electrochemical processes. Finally, the prospects of the AILs for the future development of AZIBs are proposed.

In this review, the basic principles, design strategies, and electrochemical performances of the artificial interfacial layers (AILs) for aqueous zinc-ion batteries (AZIBs) are summarized. Briefly, the issues that hinder the development of AZIBs are summarized initially. Then, different types of AILs are combed according to their structural features. Finally, the potential challenges and prospects of AILs are proposed.

Portable electrical devices have become integral to our daily lives, with many being powered by rechargeable batteries. The increasing demand for such batteries has prompted a search for alternative options. Among these alternatives, sodium-ion batteries (SIBs) stand out as promising candidates because of their operational similarity to lithium-ion batteries and cost efficiency. Despite the presence of some commercial SIB products, their overall performance falls short of meeting the requirements for large-scale manufacturing. A critical factor influencing the performance of SIBs is the cathode material. Recently, a novel concept involving high entropy has been introduced for use as a cathode material for SIBs. This review begins by introducing the high-entropy concept and then explores the methods used to synthesize cathode materials such as sodium layered oxides, Prussian blue analogs, and NASICON for SIBs. This review also presents state-of-the-art progress in these three types of materials. In the Conclusions section, we outline perspectives for high-entropy materials (HEMs). This comprehensive review aims to serve as a reference for studying HEMs in the context of SIBs.

The rapid expansion of markets for new energy power generation systems, electric vehicles, and drones has driven a significant surge in the demand for lithium-ion batteries (LIBs). However, traditional liquid-state LIBs face critical challenges, including a low energy density, significant safety risks, and a limited operational lifespan. Solid-state lithium batteries (SSLBs) have emerged as a promising solution, offering a higher energy density and improved safety, with their industrialization reliant on advancements in solid-state electrolytes (SSEs). Among these, polymer-based SSEs stand out for their lightweight, cost-effective, flexible, and easily processed nature, making them ideal for large-scale production. Notably, polyimide (PI) has gained significant attention as a leading candidate for polymer-based SSEs because of its excellent mechanical properties, thermal stability, flexibility, and flame retardancy. This review systematically examines the application of PI-based solid electrolytes (PISEs) for SSLBs, starting with their structural designs, material types, mechanisms, and key properties. It then delves into preparations, modification strategies, and advanced architectures while presenting application scenarios and performance metrics. Finally, this review highlights potential future directions for the development and optimization of PISEs for SSLBs. It will lay a solid theoretical foundation for the extensive research and application of PI in the field of SSEs and greatly promote the development of high-performance and high-security SSLBs.

Aqueous zinc-iodine batteries (AZIBs) offer intrinsic safety, low cost, and high theoretical capacity, yet their practical performance is hindered by three coupled challenges: polyiodide shuttling that depletes active material and reduces coulombic efficiency; sluggish I₂/I⁻/

Electro-conversion of CO₂, N₂, or NO_x into valuable chemicals, e.g., CO, HCOOH, and NH₃, has become a favorite for mitigating environmental pollution and addressing the energy crisis. Typical electrolysis systems, which pair a cathodic CO₂, N₂, or NO_x reduction reaction (CO₂RR, NRR, or NO_xRR) with an anodic oxygen evolution reaction (OER), hinder the economic viability and efficiency of the overall system due to the energy-intensive OER process. Innovative “Two-in-One” systems that integrate CO₂RR, NRR, or NO_xRR with a value-added oxidation process or energy storage unit, rather than OER, within a single device have emerged as promising alternatives. However, these “Two-in-One” integrated systems still face numerous pressing challenges in advancing the industrialization of CO₂-, N₂-, and NO_x-related conversion technologies, such as limited application scenarios, low efficiency, and restricted products. Herein, we discuss the technological breakthroughs of “Two-in-One” systems from the perspective of value-added chemical co-production, environmental remediation, and energy storage, aiming to provide readers with fresh research viewpoints to improve efficiency, increase product variety and selectivity, maximize product value, and reduce costs. Specifically, the design principles of “Two-in-One” systems, specific design strategies for dual-value-added chemical co-production, environmental pollutant recycling, and energy storage applications, along with techno-economic and environmental impacts, are discussed in detail. Finally, key research opportunities and challenges are highlighted to facilitate further developments.

From the perspectives of value-added chemical synthesis, environmental remediation, and energy storage, we discuss innovative “Two-in-One” systems that integrate CO₂, N₂, or NO_x reduction reactions with a value-added oxidation process or energy storage unit, rather than oxygen evolution reaction (OER), within a single device, as promising alternatives for solving the problem of high energy consumption and meeting real-world sustainability needs.

With the increasing demand for sustainable energy solutions, electrocatalysis has become an essential technology for energy conversion and storage. Despite significant advancements, traditional electrocatalysts still face persistent challenges in enhancing activity and improving stability. Recent studies have shown that vacancy engineering—modifying the atomic structure of materials through the introduction of vacancies—can significantly enhance catalytic efficiency and durability. As such, this approach provides a promising pathway to advance electrocatalysis. This review first explains the mechanisms of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) and then provides a comprehensive overview of the application synthesis and characterization of various vacancies strategies, including anionic vacancies, cationic vacancy, and combined anionic–cationic vacancies. The review deeply analyzes the role of vacancies in the electrocatalysts for HER, OER, and overall water splitting. Moreover, the advanced characterization techniques for vacancies are introduced to demonstrate the effects of vacancies from the atomic level. Finally, the review addresses the current challenges and limitations associated with vacancy engineering and proposes potential directions for future research.