Alkaline-earth-metal regulated metal carbides with bioinspired gradient OH spillover for efficient and long-lasting direct seawater electrolysis

Direct seawater splitting has been considered one of the most promising sustainable approaches for producing green hydrogen. However, the complexity and corrosion of seawater composition still hinder the efficiency, where hydroxide precipitation and sluggish proton supply are the main problems. Catalysts that can simultaneously facilitate proton supply and avoid hydroxide precipitation formation are highly desired. Here, inspired by natural water splitting-related enzyme systems, we report the de novo design of an alkaline-earth-metal (Mg, Ca, and Sr) and ruthenium (Ru) atom co-engineered gradient OH spillover pathway on metal carbides (WC) for efficient and long-lasting direct seawater electrolysis. The fast water dissociation at the Ru and WC interface and gradient OH* transferring local environment created by alkaline metal atoms will retard the formation of insoluble precipitates and provide an efficient proton supply. Consequently, the synthesized C-WC-RuMg catalyst exhibits excellent hydrogen evolution performance in direct seawater with a low overpotential of 180 mV at 10 mA cm⁻² and stability for more than 35 h. Meanwhile, similar phenomena can also be observed in C-WC-RuCa and C-WC-RuSr. We anticipate that this study will be crucial for the development of high-performance and powerful cathodes for direct seawater splitting and many other catalysts. © The Royal Society of Chemistry 2024.