Hierarchical nitride/phosphide heterostructure for efficient and ultrastable Ampere-level hydrogen production

Towards large-scale hydrogen production via water splitting, it is crucial to enhance the mechanical stability of electrocatalysts while maximizing the formation and utilization of efficient active sites through rational morphological design and electronic modulation. Here, a hierarchical nitride/phosphide heterostructure electrocatalyst is successfully constructed, consisting of amorphous 2D NiCoP nanosheets vertically grown on crystalline 1D NiMoN nanorod arrays. This unique structure facilitates the formation and exposure of efficient active sites while endowing NiMoN/NiCoP catalyst with a highly hydrophilic and superaerophobic surface. Accordingly, it exhibits an ultralow overpotential of 126 mV at 1000 mA cm –2 for the hydrogen evolution reaction (HER) in 1 mol L –1 KOH. Notably, as a bifunctional catalyst, it requires merely 1.74 V in 1 mol L –1 KOH solution and 1.77 V in an anion exchange membrane water electrolyzer (AEMWE) to achieve 1000 mA cm –2 of current density, while maintaining stable electrolysis for up to 1600 and 300 h, respectively. Theoretical calculations indicate the interaction between NiMoN and NiCoP leads to the redistribution of charge density. This promotes H 2 O adsorption and dissociation, also optimizes the adsorption of H* intermediates at the heterointerfacial Ni sites, consequently improving the HER activity. These characteristics highlight its promising applicability as an Ampere-level catalyst for hydrogen production.