Phosphorus and Sulfur Co‐Doped Cobaltous Oxide Synthesized by an Inorganic‐Salt‐Assisted Method: Reaction Mechanism and Electrocatalytic Application

Abstract

Inorganic‐salt‐assisted non‐metallic heteroatom (phosphorus and sulphur) co‐doped cobaltous oxide (P/S‐CoO) has been reported. Potassium sulphate (K 2 SO 4 ) was used as inorganic source of sulphur (S), while triphenyl phosphine (PPh 3 ) was used as phosphorus (P) source. A stepwise mechanistic investigation into the doping process revealed the decomposition of PPh 3 triggered the release of both the elemental sulphur and phosphorus via a reducing reaction environment. The transformation of cobalt‐PPh 3 complex into cubic cobalt (II) oxide along with the successful co‐doping (P and S) was achieved by high temperature calcination at 800 °C but preserved the bulk CoO crystalline structure. The as synthesized P/S‐CoO demonstrated an unprecedented enhancement on the oxygen evolution activity compare to that of pristine CoO with the current density of 10 mA/cm 2 at the overpotential of 293 mV in 1.0 M KOH electrolyte and profound stability at different current densities.