CoSe/CoSe2 Mott–Schottky heterostructures embedded in porous carbon nanofibers toward efficient bifunctional catalysis in zinc–air batteries

Abstract

The exploration of highly efficient bifunctional oxygen electrocatalysts is crucial for zinc–air batteries (ZABs). Transition metal selenides with low cost and high catalytic activity have demonstrated considerable potential in the field of catalysis. Herein, a novel CoSe/CoSe₂ Mott–Schottky heterostructure is embedded in a porous, N-doped carbon (PNC) nanofiber network to fabricate a CoSe/CoSe₂@PNC bifunctional catalyst for ZABs. Theoretical analyses reveal that the CoSe/CoSe₂ heterointerface induces a strong built-in electric field, which effectively optimizes the adsorption of oxygen intermediates and promotes bifunctional catalytic behavior. Experimental results demonstrate that the PNC nanofiber network provides high electrical conductivity and effectively prevents the heterostructures from agglomerating during cycling. Benefitting from both advantages, the CoSe/CoSe₂@PNC catalyst achieves remarkable bifunctional activity and superior stability. Integrated with a CoSe/CoSe₂@PNC air cathode, an aqueous ZAB is assembled, and it exhibits a peak power density of 215.13 mW cm⁻² and high stability during long-term cycling (400 h). Furthermore, the solid-state ZAB with flexible CoSe/CoSe₂@PNC shows superior reliability and high stability under various mechanical deformations. Thus, this study provides an effective strategy for the design of nonprecious-metal-based oxygen electrocatalysts and promotes the development of high-performance ZABs for diverse working conditions.