CoS2 quantum dots modified by ZIF-67 and anchored on reduced graphene oxide as an efficient catalyst for hydrogen evolution reaction

Abstract Hydrogen energy has become one of the most potential sources for replacing fossil fuels due to its environmental friendliness and high energy conversion rate. Electrolyzed water is a hydrogen evolution process with high efficiency, no by-products, and high hydrogen purity. Here, we propose to use ZIF-67 as the precursor to prepare three-dimensional multilayer rGO supported CoS2 quantum dots (CoS2QDs@rGO) through a two-step hydrothermal method and one-step calcinations method. The as-prepared electrocatalyst with maximum exposure of edge active sites is highly efficient for hydrogen evolution reaction (HER), delivering an extremely small Tafel slope of 78 mV dec-1, and prominent durability. Density functional theory (DFT) calculations reveal that decoration of CoS2QDs not only obviously changes Gibbs free energy of hydrogen adsorption (ΔGH*), but also offers more active sites for HER, conspicuous promoting the catalytic activity of as-obtained electrode materials. It can be expected that our CoS2 quantum dots mounted on three-dimensional multilayer rGO with ZIF-67 as the precursor, will provide a novel, high-yield and effective catalytic material for energy conversion applications.