Enhanced Oxygen Evolution Activity of CoO–La0.7Sr0.3MnO3−δ Heterostructured Thin Film

The design and fabrication of highly efficient oxygen evolution reaction (OER) electrocatalysts is crucial for further development of electrochemical conversion devices. In this paper, the pulsed laser deposition technique was first used to fabricate high quality and well-defined CoO-La0.7Sr0.3MnO3-δ (LSMO) heterostructured electrocatalysts. The current density was about 70 and 20 times larger with respect to single-phase CoO and LSMO thin film electrocatalysts, respectively. The enhancement of electrocatalytic activity was investigated in detail by using electrochemical and X-ray photoemission/absorption spectroscopies. The introduction of the LSMO intermediate layer not only promoted charge transfer kinetics but also resulted in a larger Co3+/Co2+ ratio due to the partial oxidation of the CoO layer during film growth. The design of coatings with a tunable oxygen electrocatalytic activity implementing the heterostructure engineering approach was demonstrated.