WC/Co₇Fe₃ heterojunction embedded in N,P co-doped hierarchical carbon enables rechargeable/flexible Zn-air battery

Rational design and synthesis of bifunctional oxygen electrocatalysts with high activity and stability are key challenges in the development of rechargeable Zn-air batteries (ZABs). In this paper, tungsten carbide (WC) and Co₇Fe₃ embedded in N,P co-doped hierarchical carbon (WC/Co₇Fe₃-NPHC) was prepared by using zeolite imidazolate frameworks as precursor. Density functional theory demonstrates that the mutual adjustment among the WC, Co₇Fe₃, and N,P co-doped carbon at the three-phase heterojunction interface makes the catalyst possess moderate adsorption strength, and greatly improves the conductivity and electron transfer rate of the catalyst. As a result, the WC/Co₇Fe₃-NPHC exhibits a low overall oxygen redox potential difference of 0.72 V, while the ZAB assembled by WC/Co₇Fe₃-NPHC as an air cathode exhibits ultra-long cycle stability of over 550 h. Futhermore, WC/Co₇Fe₃-NPHC can keep good charge and discharge stability at different bending angles when applied to flexible solid ZAB.