Processable Surface Modification of Nickel-Heteroatom (N, S) Bridge Sites for Promoted Alkaline Hydrogen Evolution

Abstract

Nickel‐heteroatoms bridge sites are important reaction descriptors for many catalytic and electrochemical processes. Herein we report the controllable surface modification of nickel-nitrogen (Ni−N) bridge sites on metallic Ni particles via a simplified vapor‐assisted treatment approach. X‐ray absorption spectroscopy (XAS) and Operando Raman spectroscopy verifies the interaction between Ni and surface‐anchored N, which leads to distorted Ni lattice structure with improved wettability. The Ni−N bridge sites with appropriate N coverage level plays a critical role in the enhanced hydrogen evolution reaction (HER) and the optimized electrode (Ni−N0.19) has demonstrated superior HER performances with low overpotential merely of 42 mV for achieving a current density of 10 mA cm−2, as well as favorable reaction kinetics and excellent durability in alkaline electrolyte. DFT calculations revealed that the appropriate N‐coverage level can lead to the most favorable ΔGH* kinetics for both adsorption of H* and release of H2, while high N coverage (Ni−N0.59) results in weaker H* adsorption, thus a decreased HER activity, corresponding well to our experimental observations. Furthermore, this generic synthetic approach can also be applied to prepare S‐modified Ni HER catalyst by generating hydrogen sulfide vapor.