Frontiers in electrocatalytic water splitting: Mechanistic pathways, catalytic engineering, and kinetic challenges

This insightful review explores the electrochemical principles and energy potential of electrocatalytic water splitting (EWS). It highlights recent advancements, identifies key challenges, and underscores the pivotal role of EWS in enabling the transition to sustainable energy systems. This work contextualizes the significance of green hydrogen in global decarbonization pathways and examines the historical progression of electrocatalysis. The fundamental thermodynamics and mechanistic pathways governing both the hydrogen and oxygen evolution reactions (HER and OER) are analyzed, highlighting energy barriers and rate-determining steps. Various electrode architectures and electrochemical cell configurations are evaluated, including a comparative assessment of key electrolyzer technologies and their performance characteristics. Furthermore, we critically examine recent advances and persistent limitations across the landscape of electrocatalysts, spanning noble metal-based materials, earth-abundant transition metal compounds, and emerging materials. Design principles and mechanistic insights drawn from electronic structure modulation, defect engineering, doping strategies, and nanoscale morphology control are elucidated to establish robust structure-property-performance relationships. Major challenges including sluggish oxygen evolution kinetics, catalyst degradation mechanisms, and the integration of devices with intermittent renewable energy sources are thoroughly examined. This work also debates advanced strategies such as hybrid photoelectrochemical systems, flexible device architectures, and the direct utilization of non-traditional water sources (e.g., seawater, wastewater) as promising pathways for future development. Finally, it is specifically distinguished by its critical focus on bridging the gap between fundamental electrocatalysts development and practical system-level integration, addressing the challenges of scalability and deployment under industrially relevant conditions. This comprehensive review provides a strategic outlook and identifies key scientific priorities for optimizing EWS systems toward efficient, robust, and scalable hydrogen generation.