Efficient MnO and Co nanoparticles coated with N-doped carbon as a bifunctional electrocatalyst for rechargeable Zn-air batteries

Developing the low-cost, durable, and efficient bifunctional electrocatalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) plays an important role in the commercial implementation of the Zn-air batteries. Herein, we design and synthesize the MnO and Co nanoparticles coated with N-doped carbon ([email protected]) as an excellent bifunctional oxygen electrocatalyst. It is found that the optimal [email protected] exhibits outstanding ORR performance with a positive half-wave potential of 0.82 V and excellent OER activity with a small overpotential of 360 mV at 10 mA cm−2. When applied in the liquid Zn-air battery, [email protected] displays a high maximum power density of 153 mW cm−2, a large specific capacity of 776 mAh g−1 and the excellent cycling stability with a negligible increase after 300 h. Furthermore, the fiber-shaped all-solid-state Zn-air battery also displays remarkable stability at high current density. This study offers a facile strategy to construct a high-efficient, low-cost, and durable transitional metal-based bifunctional electrode for renewable energy applications.