Interface engineering of Co3S4@Co3O4/N, S-doped carbon core@shell nanostructures serve as an excellent bifunctional ORR/OER electrocatalyst for rechargeable Zn-air battery

Herein, a class of Co3S4@Co3O4/NSC (N, S-doped carbon) composites with [email protected] nanostructures were facilely fabricated through a two-step pyrolysis-oxidation strategy using methyl orange and cobalt chloride as raw materials. By constructing heterointerfaces between different components and controlling the surface oxidation degree, the interfacial and synergistic effects endowed the composited catalysts tailorable and excellent bifunctional electrocatalytic activities on oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). A rechargeable Zn-air battery (ZAB) with the optimized catalyst Co3S4@Co3O4/NSC-260-8 as air cathode has shown excellent performance with a high specific capacity of 885 mAh·gZn−1 and energy density of 948 Wh·kgZn−1 (at 20 mA·cm−2), which is higher than 836 mAh·gZn−1 and 929 Wh·kgZn−1 of the one employing Pt/C (20%) + RuO2 as air cathode under the same conditions. The catalyst also showed robust stability and no obvious decrease in the voltage was observed after 200 h charging and discharging cycles. This work presents a feasible concept to design and construct heterostructural and multifunctional composite catalysts with heterointerfaces.