2LaCo0.7Fe0.3O3/N-doped carbon bifunctional electrocatalyst derived from g-C3N4 nanosheets for zinc-air battery

Perovskite oxides have been widely studied as one of the excellent bifunctional oxygen electrocatalysts (ORR: Oxygen Reduction Reaction, OER: Oxygen Evolution Reaction) due to its flexible crystal structure and low cost. Herein, 2LaCo0.7Fe0.3O3/N-doped carbon is prepared by sol-gel method using g-C3N4 nanosheets as carbon source and nitrogen source. The LaCo0.7Fe0.3O3 nanoparticles have excellent dispersibility on the N-doped carbon substrate and the composite material has higher oxygen vacancy concentration, showing enhanced bifunctional electrocatalytic activity (△E=Ej=10,OER-E1/2,ORR=1.03 V) compared with the original LaCo0.7Fe0.3O3 (△E = 1.12 V). Moreover, 2LaCo0.7Fe0.3O3/N-doped carbon-based Zn-air battery presents excellent cycling stability (over 24 h) and high peak power density of 116 mW cm−2. Density functional theory (DFT) calculations revealed the mechanism of improvement electrocatalytic activity of 2LaCo0.7Fe0.3O3/N-doped carbon, which comes from the regulated electronic structure, including enhanced conductivity and the covalence of Co-O bond, reducing the free energy change of rate-determining step. This study provides a novel strategy for the design and prepare perovskite-type bifunctional electrocatalysts.