Unleashing the Potential of Metastable Materials in Electrocatalytic Water Splitting

Electrocatalytic water splitting is pivotal for advancing the hydrogen economy, yet conventional stable-phase catalysts are constrained by rigid crystal structures and electronic states, leading to fixed active sites, limited adaptability, and sluggish kinetics. Metastable materials emerge as promising alternatives due to their structural flexibility and tunable electronic properties; however, their dynamic regulatory mechanisms remain underexplored. This review uniquely offers a comprehensive analysis of metastable catalysts, emphasizing how factors such as size, phase structure, electronic properties, defects, and interfaces significantly enhance catalytic performance. By dissecting a range of materials (metals, alloys, oxides, sulfides, nitrides, and hydroxides), we elucidate precise modulation strategies that improve efficiency and stability. Practical applications highlight their superior adaptability and activity compared to traditional catalysts. Addressing key challenges and technical bottlenecks, this review provides innovative insights and strategic directions for optimizing metastable materials, thereby advancing efficient water splitting and sustainable energy conversion technologies.