Tailoring Chemical Microenvironment of Iron-Triad Electrocatalysts for Hydrogen Production by Water Electrolysis

Electrocatalytic water splitting holds promise for green hydrogen production, but its widespread adoption is challenged by the trade-off between energy consumption and production costs. Iron-triad-based materials are of considerable interest as electrocatalysts due to their unique chemistry and electronic structure, which facilitate moderate intermediate adsorption energies and offer tolerance to site solvation and deactivation. However, the long-term durability of those electrocatalysts remains poorly understood, hindering advanced progress. This review summarizes the fundamentals of water electrolysis chemistry, the challenges in evaluating the catalytic performance, and advances in modulating the chemistry of iron-triad active sites for water splitting, with a focus on alkaline water electrolysis, particularly anion exchange membrane water electrolysis (AEMWE). It also discusses recent developments in iron-triad electrocatalysts for water electrolysis under acidic conditions. A key emphasis is placed on the structure–activity relationships resulting from tailored iron-triad active center chemistry. Furthermore, the review explores engineering strategies, such as near-surface and chemical microenvironment modification to enable self-healing, reconstruction, and alternative catalytic mechanisms, including the localized oxide path mechanism. Finally, it examines the challenges and future prospects of sustainable hydrogen production, including rational catalyst design, scalable synthesis techniques, and in-depth physicochemical and electrochemical studies.