The effect of annealing temperature, reaction time, and cobalt precursor on the structural properties and catalytic performance of CoS2 for hydrogen evolution reaction

Abstract

In this study, cobalt disulfide (CoS2) nanostructures are synthesized using a simple hydrothermal method. The effects of experimental parameters including cobalt precursor, reaction times, and reaction temperatures are investigated on the structure, morphology and electrocatalytic properties of CoS2 for hydrogen evolution reaction (HER). The characterization of as-prepared catalysts is performed using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS). The HER efficiency of the catalysts is examined using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) methods in 0.5 M H2SO4 solution. Furthermore, chronoamperometry (CA) is used for stability evaluation. The catalyst obtained from cobalt acetate precursor, within 24 h at 200 °C exhibits superior electrocatalytic activity with a low onset potential (139.3 mV), low overpotential (197.3 mV) at 10 mA. cm−2 and a small Tafel slope of 29.9 mV dec−1. This study is a step toward understanding the effect of experimental parameters of the hydrothermal method on HER performance and developing optimal design approaches for the synthesis of CoS2 as a common electrocatalyst.