Co-doped CeO2/N–C nanorods as a bifunctional oxygen electrocatalyst and its application in rechargeable Zn-air batteries

Abstract

The development of electrocatalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) with high-activity and atability still remain great challenges for rechargeable Zn-air batteries. Herein, a new type of Co-doped Ce–N–C bifunctional electrocatalyst has been synthesized through a simple two-step method, which realizes the high dispersion of Co3O4 on the CeO2 carbon frame and stabilizes its specific surface area. Benefiting from the synergistic interaction between Co3O4 and CeO2, the conductivity of the electrocatalyst is improved and the oxygen reduction reaction/oxygen storage properties are promoted. The resultant Co3O4-CeO2@N–C catalyst shows remarkable ORR activity with the high initial potential (E 0 = 0.8 V), the large limiting current density (j L = 6 mA cm−2), and a low Tafel slope (81 mV dec−1). In full cell tests, Co3O4-CeO2@NC as the oxygen electrode exhibites superior charge/discharge capacity and excellent cycle stability. The assembled Zn-air battery achieves a maximum power density of 110 mW cm−2 at a current density of 180 mA cm−2, and a high specific capacity of 780 mAh g−1 at a discharge current density of 10 mA cm−2.