Regulating the Interfacial Electron Density of La 0.8 Sr 0.2 Mn 0.5 Co 0.5 O 3 /RuO x for Efficient and Low-Cost Bifunctional Oxygen Electrocatalysts and Rechargeable Zn-Air Batteries.

La 0.8 Sr 0.2 Mn 0.5 Co 0.5 O 3 (LSMC) perovskite anchored with RuO x (LSMC-Ru) is fabricated as a new bifunctional electrocatalyst, with low dosage (2.43 wt %) and high utilization of noble metal Ru. The LSMC-Ru exhibits outstanding bifunctional activity with a low potential gap of 0.72 V between the oxygen evolution reaction (OER) potential at 10 mA cm -2 and the oxygen reduction reaction (ORR) half-wave potential. The strong electronic interaction between RuO x and LSMC is confirmed by both experiments and theoretical calculations. Consequently, the electron-rich Mn centers promote ORR, while the electron-deficient Ru centers facilitate OER. A Zn-air battery using the LSMC-Ru air electrode delivers a peak power density of 159 mW cm -2 and a low charge-discharge potential gap of 0.58 V at 2 mA cm -2 . The high round-trip energy efficiency of 60.6% is retained after 300 cycles. This strategy of anchoring a low dosage noble metal catalyst to perovskite can be extended to other systems of noble metal-non-noble metal composite electrocatalysts to achieve both competitive performance and low cost.