Recent advances of non-noble metal catalysts for efficient water electrolysis: types of water reactors, reaction mechanisms, and catalyst categories

Electrocatalytic water splitting offers a sustainable pathway for hydrogen production, yet the high cost and sluggish kinetics of noble-metal catalysts (e.g., Pt, IrO 2 , and RuO 2 ) severely hinder its commercialization. Recently, non-noble metal electrocatalysts have shown excellent activity (η 10 < 200 mV) and long-term stability for water electrolysis, demonstrating potential to replace Ir/Ru-based catalysts. This review analyses non-noble metal electrocatalysts from three dimensions, namely electrolysis reactors, reaction mechanisms, and catalyst design. Focusing on recent advances in catalyst design, we demonstrate that heterostructure construction and interface engineering are effective strategies for enhancing electrocatalytic performance. We also emphasize the role of these strategies in promoting water-splitting kinetics and enhancing long-term stability. It is further emphasized that maintaining long-term stability (>1000 h) at high current densities remains a core bottleneck for industrial applications. Finally, the main challenges and future opportunities of non-noble metal electrocatalysts are discussed.