Heterogeneous CoS2/MS2 microspheres for an efficient oxygen evolution reaction

Abstract

Delicately fabricating efficient electro-catalysts to boost the catalytic kinetics of the oxygen evolution reaction (OER) is essential for realizing the efficient performance of water splitting into hydrogen to alleviate environmental issues and the energy crisis. Here, heterogeneous and hollow microspheres (denoted as CoS₂/MS₂-HPMS, M = Fe, FeCo) were obtained by the sulfurization of Fe³⁺-decorated ZIF-67 hollow microspheres (ZIF-67-HMS). At a current density of 10 mA cm⁻², the prepared CoS₂/MS₂-HPMS showed an overpotential of 217 mV for the OER, which is lower than that of commercial RuO₂ (336 mV). Density functional theory calculations demonstrated low reaction free energies of the intermediates of the OER and significant charge accumulation at the heterojunction interface between CoS₂ and FeCoS₂. This work establishes a method for the assembly of nanoparticles and the construction of heterojunctions.