Constructing Built-In Electric Field in Co/Co9s8 Heterojunction Encapsulated in N, S Co-Doped Carbon Polyhedron for High-Efficiency Oxygen Electrocatalysis

Achieving a subtle equilibrium between the activity and durability of transition metal chalcogenides (TMCs) towards oxygen reduction (ORR) and oxygen evolution (OER) reactions remains a formidable challenge.Therefore, we present a built-in electric field (BEF) tactic to build Co/Co9S8 heterojunctions with larger work function difference (ΔΦ) as bifunctional eletrocatalysts for high-efficiency zinc-air batteries (ZABs). Impressively, Co/Co9S8@NSC shows a higher half-wave potential (E1/2) of 0.88 V for ORR and a lower overpotential (Ej=10) of 137 mV at 10 mA·cm-2 for OER. Moreover, ZABs based on Co/Co9S8@NSC electrocatalysts exhibit an impressive power density of 267.83 mW·cm-2 and robust cyclability over 1000 h at 10 mA·cm-2. The experiments and theoretical studies elucidate that the interface-induced electric field effect facilitates the redistribution of interfacial charge, thereby improving the covalency of the Co-S bond. Additionally, it effectively promotes charge transfer and optimizes adsorption of oxygen intermediate in both ORR and OER.