Superdurable\nBifunctional Oxygen Electrocatalyst for\nHigh-Performance Zinc–Air Batteries

Abstract

The\ndevelopment of high-efficiency and durable bifunctional electrocatalysts\nfor both the oxygen reduction reaction (ORR) and oxygen evolution\nreaction (OER) is critical for the widespread application of rechargeable\nzinc–air (Zn–air) batteries. This calls for rational\nscreening of targeted ORR/OER components and precise control of their\natomic and electronic structures to produce synergistic effects. Here,\nwe report a Mn-doped RuO₂ (Mn-RuO₂) bimetallic\noxide with atomic-scale dispersion of Mn atoms into the RuO₂ lattice, which exhibits remarkable activity and super durability\nfor both the ORR and OER, with a very low potential difference (Δ<i>E</i>) of 0.64 V between the half-wave potential of ORR (<i>E</i>_1/2) and the OER potential at 10 mA cm^–2 (<i>E</i>_<i>j</i>10) and a negligible\ndecay of <i>E</i>_1/2 and <i>E</i>_<i>j</i>10 after 250 000 and 30 000\nCV cycles for ORR and OER, respectively. Moreover, Zn–air batteries\nusing the Mn-RuO₂ catalysts exhibit a high power density\nof 181 mW cm^–2, low charge/discharge voltage gaps\nof 0.69/0.96/1.38 V, and ultralong lifespans of 15 000/2800/1800\ncycles (corresponding to 2500/467/300 h operation time) at a current\ndensity of 10/50/100 mA cm^–2, respectively. Theoretical\ncalculations reveal that the excellent performances of Mn-RuO₂ is mainly due to the precise optimization of valence state\nand <i>d</i>-band center for appropriate adsorption energy\nof the oxygenated intermediates.