Transition Metal-Oxide High Entropy Microstructure for Alkaline Hydrogen Evolution Reaction

Abstract Hydrogen (H2) is widely recognized as a sustainable, non-polluting renewable fuel. Despite significant progress in hydrogen evolution reaction (HER), fundamental understanding of the reaction mechanisms and structure–activity relationships under alkaline conditions remains incomplete. Furthermore, the development of catalysts that exhibit high activity, durability, and stability under realistic operating conditions is essential for the large-scale deployment of hydrogen production technologies. In this context, studying the HER under alkaline conditions is not only of academic interest but also of practical importance for future hydrogen-based energy systems, including alkaline electrolyzers. Alkaline water electrolysis is a promising technology for sustainable hydrogen production, where water gets split into hydrogen and oxygen using electricity in an alkaline medium. Alkaline water electrolyzers have advantages over acidic systems, as they allow the use of non-precious metal catalysts, making them more cost-effective. By leveraging renewable electricity, alkaline water splitting can yield green hydrogen, a clean fuel that emits only water when used, making it a viable alternative for future energy needs. In this work, a high entropy metal oxide electrocatalyst has been synthesized via simple ball milling technique. The catalyst powder was thoroughly characterized, and its activity was evaluated for HER in alkaline medium. Furthermore, to explore the practical use, accelerated durability test was performed for 500 cycles, where it showed high stability.