Fe-doped Ni3S2/NiS heterojunction with improved electrocatalytic activity and stability for the alkaline oxygen evolution reaction

Abstract

During the oxygen evolution reaction (OER), Ni-based sulfide catalysts undergo dynamic restructuring under high current operating conditions, which can have a detrimental impact on their activity and stability. In this study, we have developed an Fe-doped Ni₃S₂/NiS heterojunction catalyst (Fe-Ni₃S₂/NiS) for the OER that exhibits exceptional durability and activity. The catalyst has demonstrated the ability to operate continuously for 72 h at current densities of 500 and 1000 mA cm⁻² without performance degradation in an alkaline electrolyte environment. This catalyst requires an overpotential of only 247 mV to drive the OER at 100 mA cm⁻². Experimental results suggest that the doped Fe acts as a sacrificial agent in the OER process, facilitating electron transfer, maintaining the high activity of Ni, and protecting the Ni–S bond from degradation. Theoretical computations further indicate that the doped Fe reduces the OER energy barrier and enhances the intrinsic conductivity of the material, thereby improving catalytic efficiency.