Advancing Multiscale-Coupled Heterointerface Catalysts for Enhanced Water Electrolysis

ConspectusGreen electricity powered water electrolysis stands out as a promising approach for hydrogen production, which is regarded as an ideal energy carrier due to its high energy density and clean combustion. However, its large-scale application is constrained by the high cost, stemming partially from the reliance on noble-metal-based catalysts to enhance the sluggish kinetics of hydrogen and oxygen evolution reactions. To address this challenge, multiscale-coupled heterointerface catalysts (MCHCs), which integrate single atoms, clusters, and nanoparticles into one independent system, have emerged as a potential alternative. They are composed of different active components at multiple scales to achieve strong synergistic effects, where single atoms provide highly active sites with unsaturated coordination environments, clusters enable tunable electronic properties to optimize intermediate binding, and nanoparticles contribute to conductive compensation and robust architecture. Through coupling engineering, these formed heterointerfaces can regulate electronic structures and geometric configurations to break the linear scaling relationship (LSR), simultaneously facilitating H2O activation and intermediate removal. Accordingly, such synergy enables the MCHCs to overcome thermodynamic and kinetic barriers in water electrolysis, significantly boosting the catalytic performance and durability.Recent progress highlights significant advancements in MCHCs. By precisely tailoring the spatial distribution and interactions of multiscale active components, the MCHCs achieve superior reaction kinetics and long-term durability under harsh conditions of water electrolysis, which address the limitations of conventional single-component catalysts. However, the exact roles of multiscale active sites remain inadequately understood, restricting the ability to fully exploit their synergistic effects. Moreover, some key challenges, including the rational design of heterointerface structures, precise tuning of multicomponent interactions, and the development of advanced characterization techniques to elucidate structure-performance relationships, require more focused investigation. Overcoming these challenges through rational interface engineering and in-depth mechanism studies is crucial for exposing the full potential of MCHCs, which will pave a way for developing high-performance catalysts toward sustainable hydrogen production.In this Account, we focus on the emerging role of MCHCs, which integrate multiple active sites across different scales to significantly enhance the catalytic performance. We comprehensively discuss the synergistic effects, design principles, and recent advancements in multiscale-coupled heterointerfaces for water electrolysis. First, we explain the origin of the sluggish kinetics of water electrolysis, emphasizing how MCHCs overcome these limitations through the precise regulation of electronic structures and geometric configurations. By balancing the seesaw relationship between water activation and intermediate desorption, these catalysts can break the intrinsic LSR limitations. Next, we summarize the latest progress in MCHCs for applications in water electrolysis, revealing dynamic interactions and structural evolution. We finally outline the current major challenges and provide a road map for future research to fully expose the potential of MCHCs for sustainable energy conversion.