Unraveling the Synergy of Chemical Hydroxylation and the Physical Heterointerface upon Improving the Hydrogen Evolution Kinetics.

ABSTRACT

Efficient transition metal oxide electrocatalysts for the alkaline hydrogen evolution reaction (HER) have received intensive attention to energy conversion but are limited by their sluggish water dissociation and unfavorable hydrogen migration and coupling. Herein, systematic density functional theory (DFT) predicts that on representative NiO, the hydroxylation (OH-) and heterointerface coupled with metallic Cu can respectively reduce the energy barrier of water dissociation and facilitate hydrogen spillover. Motivated by theoretical predictions, we subtly designed a delicate strategy to realize the electrochemical OH- modification in KOH with moderate concentration (HOM-NiO) and to channel rapid hydrogen spillover at the heterointerface of HOM-NiO and Cu, ensuring an enhanced HER kinetic. This HOM-NiO/Cu is systematically investigated by in situ XAS and electrochemical simulations, verifying its extraordinary merits for HER including the enhanced water dissociation, alleviated oxophilicity that is advantageous for consecutive adsorptions of water, and accelerated hydrogen spillover, thereby exhibiting superb HER activity with 33 and 310 mV overpotentials at the current densities of 10 and 1000 mA cm-2 in 1.0 M KOH, outperforming the Pt/C. This study might provide a reasonable strategy for the functionalized design of superior electrocatalysts.