Design of alternative oxidation processes for hybrid water electrolysis systems: recent progress and perspective

Hybrid water electrolysis (HWE) has emerged as a promising electrochemical strategy for sustainable hydrogen production by coupling thermodynamically favorable small molecule oxidation reactions with the hydrogen evolution reaction (HER). This approach offers significant advantages in reducing energy input, avoiding explosive gas mixtures, and improving overall process safety. This review provides a comprehensive summary of the recent developments in HWE systems with alternative anodic oxidation reactions, such as biomass oxidation upgrading and pollutant degradation. Key anodic oxidation reactions and their corresponding mechanisms are introduced. The optimization strategies for anode catalysts are systematically discussed, including heterojunction engineering, oxyanions modulation, acid site regulation, and heterometal incorporation. In addition, current technical challenges are critically evaluated, and potential research directions are proposed, with particular attention to catalyst performance under industrial-level current densities, advanced in situ characterization, theoretical modeling, and system integration. This work aims to serve as a valuable reference for understanding the fundamental principles of HWS and for guiding the rational development of high-performance electrocatalytic systems for future energy applications.