In-Situ Formed Hydroxide Accelerating Water Dissociation Kinetics on Co3N for Hydrogen Production in Alkaline Solution.

Sluggish water dissociation kinetics on nonprecious metal electrocatalysts limits the development of economical hydrogen production from water-alkali electrolyzers. Here, using Co3N electrocatalyst as a prototype, we find that during water splitting in alkaline electrolyte a cobalt-containing hydroxide formed on the surface of Co3N, which greatly decreased the activation energy of water dissociation (Volmer step, a main rate-determining step for water splitting in alkaline electrolytes). Combining the cobalt ion poisoning test and theoretical calculations, the efficient hydrogen production on Co3N electrocatalysts would benefit from favorable water dissociation on in-situ formed cobalt-containing hydroxide and low hydrogen production barrier on the nitrogen sites of Co3N. As a result, the Co3N catalyst exhibits a low water-splitting activation energy (26.57 kJ mol-1) that approaches the value of platinum electrodes (11.69 kJ mol-1). Our findings offer new insight into understanding the catalytic mechanism of nitride electrocatalysts, thus contributing to the development of economical hydrogen production in alkaline electrolytes.