In-situ activation induced surface reconstruction on Cr-incorporated Ni3S2 for enhanced alkaline hydrogen evolution reaction

Abstract

Ni3S2 has been emerging as one of the most promising hydrogen evolution reaction (HER) catalysts because of its moderate activity, exceptional electrical conductivity, as well as scalable methodologies, however, high energy barrier of H2O dissociation and weak desorption of H* intermediate severely hinder its HER kinetics. Here, a novel Cr-incorporated Ni3S2 is grown on Ni mesh substrate (denoted as Cr-Ni3S2/NM) by a one-step electrodeposition approach, which contributes large surface area with abundant Ni3S2/Cr2S3 heterojunctions. Consequently, it undergoes a surface reconstruction after in-situ activation (denoted as A-Cr-Ni3S2/NM), which not only enhances charge and mass transfer, but also alters the electronic structure by introducing more oxygen species on the catalyst surface and S vacancies. Using theoretical calculations, this in-situ activation is revealed not only to promote the charge transport but also boost the HER kinetics by strengthening OH* desorption for H2O dissociation and facilitating the desorption of H* intermediates. As a result, the fabricated A-Cr-Ni3S2/NM demonstrates exceptional HER performance with a small overpotential of 78 mV to deliver a current density of -10 mA/cm2 along with a stability of over 200 h, under 100 mA/cm2. Surface reconstruction has been intensively studied on the catalysts for oxygen-evolved reaction, while we illustrated that it also plays a great and positive role on Cr-Ni3S2 HER catalysts in this study, thus providing a pathway for achieving high-performance HER catalysts.