Durable built-in electric field in CoSe2-FeSe2@NC on N-doped honeycomb carbon for long-term efficient oxygen electrocatalysis toward zinc-air battery

Built-in electric field (BIEF) in metallic chalcogenide heterostructures has recently attracted significant attention due to its special interfacial electronic structure and appropriate reaction microenvironment for improving electrocatalytic performance. However, constituent dissolution issues and inferior stability of transition metal selenide heterostructure severely inhibit the formed BIEF to support long-term high-activities for ORR and OER toward zinc-air battery (ZAB). Herein, BIEF was established in CoSe2-FeSe2 hetero-nanostructures encapsulated by N-doped carbon shell on N-doped honeycomb carbon (CoSe2-FeSe2@NC/NHC) for achieving long-term efficient oxygen electrocatalysis. DFT calculation results confirm that the durable BIEF formed in CoSe2-FeSe2@NC on NHC not only optimizes interfacial electronic structures and surface adsorption energy, but also offers numerous hyperactive interfacial sites during electrocatalytic reactions. Consequently, the designed CoSe2-FeSe2@NC/NHC exhibits remarkable performance for both ORR (E1/2 = 0.87 V) and OER (Ej = 10 mA cm-2 = 1.54 V), enabling superior peak power density and long-term charging-discharging stability in both liquid-state ZAB (184.3 mW cm−2 and 1350 cycles) and flexible all-solid-state ZAB (61.4 mW cm−2 and 195 cycles). The high durability of BIEF in the core–shell hetero-nanostructured electrocatalyst is crucial for long-term highly-active oxygen electrocatalysis in ZAB.