LAUSR

Abstract Oxygen evolution reaction (OER) is an important semi-reaction involved in water splitting and metal-air battery devices. Considering the high activity of CoS for OER and the superionic conductor characteristics of Ag2S, Co-Ag sulfide catalyst was synthesized by a simple solvothermal method. Small amounts of Ag2S species in the reaction system mediates the formation of CoS nanowires, which is in contrast to irregular particles obtained without Ag2S. Ag2S species with superionic conductor characteristics acting as a catalyst induces the growth of CoS nanowires via a non-typical solution-liquid-solid mechanism. The thus formed Ag+ mediated CoS nanowires show improved electrical conductivity and prominent catalytic activity, and only requires an overpotential of 293 mV to provide a current density of 10 mA cm−2 with Tafel slope of 55.3 dec−1. In addition, the catalytic activity can maintain in the i-t test for at least 30 h. The derivation of this OER catalyst after OER operation was examined, which indicates that Ag- and S- codoped CoOOH is formed on the catalyst surface after OER operation that acts as catalytic active phase for OER.