The increasing consumption of fossil fuels and the resulting rise in CO 2 emissions make the transition toward clean energy sources more urgent than ever. Among the most promising solutions, water electrolysis has emerged as a key technology for producing green hydrogen, a clean and versatile energy vector. At the heart of this process lies the performance of electrocatalysts, which govern both the efficiency and the viability of water splitting systems. This review therefore focuses on recent advances in electrocatalysts developed for hydrogen production through water splitting, with particular emphasis on alkaline and acidic environments, aiming to accelerate the development of cost-effective, durable materials that can make green hydrogen a viable cornerstone of the global energy transition. In alkaline media, special attention is given to bifunctional electrocatalysts. In acidic media, however, the two half-reactions demand distinct catalyst families: at the anode, the oxygen evolution reaction (OER) is predominantly catalysed by Ir- and Ru-based materials, although recent studies have demonstrated that certain non-noble-metal catalysts can also exhibit meaningful catalytic activity under these harsh conditions. At the cathode, the hydrogen evolution reaction (HER) has long been dominated by platinum-based catalysts nonetheless, a growing body of research has shown that alternative materials based on earth-abundant and less expensive elements can achieve competitive catalytic performance.
brahimi et al. (2026) studied this question.