Water Oxidation Catalysis Beginning with CuCo2 S4 : Investigation of the True Electrochemically Driven Catalyst.

The exploitation of efficient and stable water oxidation catalysts is a pressing challenge to solve the energy crisis. Herein, flower-like CuCo2 S4 microspheres were successfully synthesized and used as an effective water oxidation catalyst. CuCo2 S4 /NF (NF=nickel foam) affords electrocatalytic water oxidation activity, with a current density of 20 mA cm-2 at a low overpotential of 260 mV. The overpotential value is lower than that of benchmark RuO2 /NF (overpotential of 340 mV at a current density of 20 mA cm-2 ). The water oxidation activity increases linearly before nonlinearly improving with increasing pH; this indicates that the substrate changes from water to hydroxyl. The CuCo2 S4 /NF catalyst is demonstrated to be a real water oxidation catalyst based on diverse experiments.