Recent advances in innovative systems for electrocatalytic hydrogen production

Electrocatalytic water splitting driven by renewable energy has garnered significant attention for producing high-purity hydrogen (H₂) to support the H₂ economy. The focus has been on developing highly active catalysts to improve reaction kinetics and enhance the energy efficiency of water splitting. Despite progress made over the years, challenges such as a large energy penalty, high costs of noble metal-based electrocatalysts, explosive H₂/O₂ mixtures, unmatched kinetics of half-reactions, expensive ion-exchange membranes, and difficulties in H₂ distribution continue to impede the practical application of large-scale, energy-efficient water splitting. In this review, we first discuss the basics of conventional electrochemical water splitting and then introduce four innovative systems—hybrid water splitting, bipolar hydrogen production, asymmetric electrolyte electrolysis, and decoupled water electrolysis—to tackle these challenges. The review focuses on each system's principles and advancements while addressing remaining obstacles and providing a glimpse into the future. It aims to guide and inspire further research efforts to enhance the performance of water electrolysis systems, ultimately advancing the field of electrocatalytic H₂ production.