Ultrafine monodisperse NiS/NiS2 heteronanoparticles in situ grown on N-doped graphene nanosheets with enhanced electrocatalytic activity for hydrogen evolution reaction

Abstract The exploration of highly active and stable nonprecious electrocatalysts for the hydrogen evolution reaction (HER) is of great significance for the advancement of diverse sustainable energy storage and conversion systems. Herein, we demonstrate a facile one-pot hydrothermal synthesis of ultrafine and monodisperse NiS/NiS2 heteronanoparticles (ca. 3.2 nm) uniformly in situ grown on N-doped reduced graphene oxide nanosheets (denoted as NiS/NiS2@N-rGO hereafter). In such unique NiS/NiS2@N-rGO sample, the tiny-sized NiS/NiS2 heteronanoparticles with abundant intimate interfacial contacts allow the effective modification of the electronic structure and more exposure of catalytically active sites. Moreover, the conductive N-rGO support could serve as a “highway” of in-plane charge transfer and facilitate the mass diffusion during the electrocatalytic process. As a consequence, the resultant NiS/NiS2@N-rGO catalyst exhibits a superior HER performance with an overpotential of 148 mV to deliver a current density of 10 mA cm−2 in 1.0 M KOH solution. The NiS/NiS2@N-rGO catalyst could also endure long-term operation for 12 h with negligible activity attenuation and morphological change. The present study provides a feasible approach to explore efficient and robust non-noble metal-based electrocatalysts for a variety of renewable electrochemical applications.