Self-supported electrocatalyst engineering for industrial alkaline water splitting based on first-row transition metal elements

) have been considered promising alternatives to noble-metal catalysts for alkaline water electrolysis due to their abundant reserves, tunable d-orbital electron configurations, and intrinsic catalytic activities. Self-supported engineering, through directly integrated catalysts onto substrates, can effectively promote interfacial mass transfer, catalytic stability, and gas release. Therefore, the development of self-supported electrocatalytic systems based on first-row transition metals has become a central strategy to facilitate the industrial application of alkaline water electrolysis. This review systematically summarizes the latest progress in self-supported catalysts with an emphasis on rational design principles for industrial applications. The mechanisms of the alkaline hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are first outlined. Rational construction of self-supported catalysts for substrate selection and preparation methods is also introduced. Subsequently, this review systematically summarizes the recent progress in self-supported catalysts based on first-row transition metals using high current densities and various optimization strategies, including heterostructure construction, defect engineering, heteroatom doping, and amorphization control. Finally, we present insightful perspectives on the future development of advanced electrocatalysts for industrial alkaline water electrolysis. This work is expected to shed light on the rational design of next-generation high-performance and robust self-supported electrocatalysts for practical application, thus promoting the large-scale industrialization of green hydrogen production.