Co3ZnC core–shell nanoparticle assembled microspheres/reduced graphene oxide as an advanced electrocatalyst for hydrogen evolution reaction in an acidic solution

Abstract

A novel Co₃ZnC/RGO composite with Co₃ZnC microspheres deposited on reduced graphene oxide (RGO) sheets is fabricated through a facile and effective two-step strategy. The Co₃ZnC microspheres with an average diameter of 395 nm have a porous structure and are composed of Co₃ZnC core–shell nanoparticles with a size of 24.2 nm. The Co₃ZnC/RGO composite shows a significantly enhanced electrocatalytic activity for hydrogen evolution reaction (HER) with much lower overpotential (108 mV), smaller Tafel slope (83.4 mV per decade) and higher exchange current density (2.1 × 10⁻² mA cm⁻²) as compared with a pure Co₃ZnC catalyst. Besides, the Co₃ZnC/RGO composite exhibits high stability in an acidic solution; the HER catalytic activity shows almost no degradation after 1000 cycles. The enhanced performance can be ascribed to the unique porous and core–shell structure of Co₃ZnC as well as the introduction of RGO in the Co₃ZnC/RGO composite, which can promote the penetration and migration of the electrolytic ions and improve the electron transfer and transport in electrochemical measurements. This novel approach could be extended to synthesize other carbide/RGO composite nanostructures with excellent electrocatalytic activities for hydrogen generation.