N-Modified NiO Surface for Superior Alkaline Hydrogen Evolution.

Abstract

Boosting the sluggish kinetics of the hydrogen evolution reaction in alkaline environments is key for the large-scale application of water-alkali and chlor-alkali electrolysis. In this study, nitrogen atoms are used to precisely modulate electrochemical active sites on the surface of nickel oxide with low-coordinated oxygen atoms, to achieve enhanced kinetics in alkaline hydrogen evolution. Theoretical and experimental results demonstrate that surface charge redistribution after modulation facilitates both the initial water dissociation step and the subsequent recombination of Had from low-coordinated oxygen sites and desorption of OHad- from nickel sites, thus accelerating the overall hydrogen evolution process. The N-modulated nickel oxide enriched in low-coordinated oxygen atoms exhibits significantly enhanced activity with a small overpotential of -100 mV at the current density of -10 mA cm-2 and a robust stability over 90 h for hydrogen evolution in 1.0 m KOH.