Boosting the bifunctional electrocatalytic activity of nitrogen-doped graphene by electronic effect of heterovalent ion substituted perovskite oxides

Sluggish reaction kinetics of carbon-based catalysts hinder their activity in oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), which further impede commercialization of Zinc-air batteries. Here, a strategy of modifying the electronic structure of nitrogen-doped graphene (NG) through constructing it with cobalt (Co) substituted manganese-based perovskite oxides (LaMn 1-x Co x O 3 ) to accelerate its activity in OER and ORR is proposed. Co substitution is beneficial for donating electrons to oxygen-containing intermediates by inducing excessive negative charge on NG to improve kinetics in OER and ORR. The half-wave potential in ORR for LaMn 0·6 Co 0·4 O 3 @NG is 0.74 V, higher than that of LaMnO 3 @NG and LaCoO 3 @NG; the overpotential of LaMn 0·6 Co 0·4 O 3 @NG at 10 mA cm −2 is 314 mV for OER, smaller than that of LaMnO 3 @NG and LaCoO 3 @NG, supposing the superior electrochemical activity of composite catalyst with Co substitution in OER and ORR. This research offers a way in fabricating high efficient and cost-effective bifunctional electrocatalyst for Zinc-air batteries. • LaMn 1-x Co x O 3 @NG catalysts with interfacial covalent bonds are in-situ constructed. • Heterovalent ion substitution of cores modify the electronic property of outer NG. • ZABs with LaMn 0·6 Co 0·4 O 3 @NG exhibit outstanding energy density and stability.