Bifunctional N-CoSe₂/3D-MXene as Highly Efficient and Durable Cathode for Rechargeable Zn-Air Battery

Rechargeable Zn-air battery is a promising alternative to the widely used lithium-ion battery. Its practical use, however, is hindered by low power density, unsatisfactory energy efficiency, poor durability, and unstable voltage output. Here, we demonstrate a bifunctional catalyst for oxygen evolution and oxygen reduction reactions based on 3D MXene coupled with nitrogen-doped cobalt selenide nanocrystals (N-CoSe2/3D Ti3C2Tx). Combining experimental characterizations and density functional theory (DFT), the excellent performance is ascribed to enhanced intrinsic activity of CoSe2 due to electron transfer from MXene, N doping which lowers the reaction energy barriers, and 3D MXene architecture which provides large specific surface area, high porosity, and good conductivity. Moreover, Zn-air battery equipped with the developed N-CoSe2/3D MXene as the air cathode exhibits better power/energy densities and long-lasting cycling life (over 500 cycles) compared with that of mixed Pt/C and RuO2.