Electrochemical oxygen evolution catalysis of metal sulfides: a systematic study of electronic effects†

Abstract

Metal sulfides have various applications, and their unique electrochemical properties have elicited avenues for their use as electrocatalysts. Metal sulfides have demonstrated promising electrocatalytic activity for the anodic oxygen evolution reaction (OER) in water electrolysis. However, activity descriptors for the OER on metal sulfides have not yet been explored. In this study, we systematically investigate the electrocatalytic OER activities of metal sulfides and propose comprehensive OER descriptors. We select nine metal sulfides, namely, MnS, CoS₂, NiS, CuS, Cu₂S, MoS₂, ZnS, NiCo₂S₄ and CoNi₂S₄, and evaluate their OER activities as well as analyze important factors in their OER catalysis. The metal sulfides exhibit distinct OER activities based on their metallic components. Further, density functional theory calculations show a strong correlation between their OER activities and unoccupied d-band centers, similar to the case of metal oxides. Additionally, the OER activities follow a volcano plot relationship with the number of d electrons, a novel finding in this field. These insights offer a rational design guideline for developing metal sulfide-based OER electrocatalysts and contribute to advancements in green hydrogen production.