Influence of substrate materials on electrocatalytic water splitting: Mechanisms, engineering strategies, and future perspectives

Substrate materials play a decisive yet often underexamined role in electrocatalytic water splitting, extending beyond mechanical support to influence charge transport, catalyst adhesion, electrolyte accessibility, gas-bubble release, interfacial reconstruction, and long-term electrode stability. This review systematically examines how carbon-based and metallic substrates, including carbon cloth, glassy carbon, nickel foam, nickel fiber, stainless-steel mesh, and copper mesh, affect hydrogen evolution reaction and oxygen evolution reaction performance across different electrolyte environments. Particular emphasis is placed on substrate-dependent physicochemical properties, activation processes, deposition strategies, in situ surface transformations, and intermediate formation during electrocatalysis. The review further discusses substrate engineering approaches such as acid etching, alloying, plasma treatment, surface texturing, and interlayer design to enhance conductivity, durability, and catalytic efficiency. By correlating substrate stability with morphology, pH, applied potential, and reaction conditions, this work provides practical guidance for selecting and designing substrates for efficient and durable water electrolysis.