LAUSR

Abstract Homogeneous NaBH4-reduced Co3O4 thin film electrodes with enhanced oxygen evolution electrocatalysis was obtained via a controlled-synthesis route. Firstly CoOx colloids was synthesized via ethylene glycol solvothermal method and cast on conductive glass substrates. The oxygen evolution reaction (OER) electrocatalysis of these as-prepared Co3O4 thin films were then significantly enhanced via a simple surface reduction by NaBH4 solution. The OER catalytic performance of the NaBH4-reduced thin films were strongly dependent on the NaBH4 concentration. The use of NaBH4-reduced thin film electrodes for OER in alkaline solution supported higher current density and consequently a negative shifts of the onset potential compared to that of the pristine. The optimal B12.5, 20-Co3O4 thin films exhibited excellent OER catalytic performances: At the current density of 10 mA·cm-2, a low overpotential of 365 mV and a small Tafel slope of 59.0 mV·dec-1 were observed. In addition, these B12.5, 20-Co3O4 thin film electrodes possessed good stability that can well recover its OER performance in a 24-h chronoamperometric stability test.