Nonmetallic Nitrogen-Doped MnO 2 as Highly Efficient Oxygen Electrocatalyst for Rechargeable Zinc-Air Batteries.

Zinc-air batteries (ZABs) have been considered as one of the most promising energy storage devices to solve the problem of energy crisis and environmental pollution. In this work, we reported the synthesis of nitrogen-doped MnO 2 (N-MnO 2 ) to replace the noble metal electrocatalysts for air cathode in ZABs. The doped N atoms here introduced more Mn 3+ and oxygen vacancies for MnO 2 , enhancing charge transfer property and accelerating surface intermediate product during the oxygen reduction reaction (ORR). Hence, the best N-MnO 2 achieved remarkable electrocatalytic activities towards ORR (half-wave potential of 0.797 V vs. RHE), and reversible oxygen overpotential of around 0.842 V, which is better than or comparable to the Pt/C and Mn-based catalysts reported recently. Moreover, the homemade ZABs based on N-MnO 2 showed the maximum power density of 132.8 mW cm -2 and excellent cyclic stability.