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

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.