Fe-doped CoS2 Nano-octahedra as Electrocatalysts for Hydrogen Evolution Reaction in Acidic Medium

Abstract

Developing efficient and robust noble-metal-free electrocatalysts for the hydrogen evolution reaction (HER) under acidic conditions remains a significant challenge. CoS2 was developed as an efficient electrocatalyst for HER, exhibiting superior conductivity and intrinsic catalytic activity. We present Fe-doped CoS2 nano-octahedra synthesized via controlled hydrothermal sulfidation, serving as an effective electrocatalyst for HER. The incorporation of Fe into the pyrite CoS2 lattice alters its electronic configuration, enhances the adsorption energies of hydrogen evolution reaction intermediates, and increases the density of electrochemical active sites. The optimized 8% Fe-doped CoS2 attains a reduced overpotential of 57 mV at 10 mA cm-2 and Tafel slope of 56 mV·dec⁻¹, surpassing that of pristine CoS2 nano-octahedra. The catalyst demonstrates approximately 96 hours of stable performance in 0.5 M H2SO4, highlighting its stability in acidic medium. This study presents a cost-effective and scalable method for developing transition-metal chalcogenides with altered electronic structures to enhance hydrogen generation in acidic conditions.