Multicomponent Nitride/High-Entropy Alloy Heterostructures as Highly Active and Stable Electrocatalysts for Ampere-Level Water Oxidation.

Developing highly active and stable oxygen evolution reaction catalysts is paramount for cost-effective large-scale green hydrogen production via water electrolysis. Here we report nonprecious metal-based multicomponent nitride/high-entropy alloy heterostructures as cost-effective electrocatalysts to efficiently mediate alkaline water oxidation by in-situ configurating cooperative Brønsted basic oxyanion-solid interfaces during phase transformation of multicomponent nitride into amorphous N-doped NiFeCoMoCrOOH along with partial dissolution of high-value metals of Mo and Cr to form molecular MoO42- and CrO42- species. The protonation of Brønsted basic oxyanions facilitates the critical *OOH intermediate formation on N-doped NiFeCoMoCrOOH with near-optimal adsorption energy, substantially accelerating the oxygen evolution reaction kinetics. Consequently, the heterostructure electrode exhibits superior oxygen evolution reaction electrocatalysis in 1 M KOH solution, delivering ultrahigh current density of ~ 2.5 A cm-2 at low overpotential of 300 mV. Its alkaline water electrolyzer operates stably at ampere-level current density for > 1700 h. Our findings reveal an unconventional molecule-assisted multi-site mechanism of multicomponent catalysts to accelerate multiple-intermediate reaction.