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-xCo_xO₃) 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_0·6Co_0·4O₃@NG is 0.74 V, higher than that of LaMnO₃@NG and LaCoO₃@NG; the overpotential of LaMn_0·6Co_0·4O₃@NG at 10 mA cm⁻² is 314 mV for OER, smaller than that of LaMnO₃@NG and LaCoO₃@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.