Constructing Stable Bifunctional Electrocatalyst of Co─Co ₂ Nb ₅ O ₁₄ with Reversible Interface Reconstitution Ability for Sustainable Zn‐Air Batteries

Transition metal and metal oxide heterojunctions have been widely studied as bifunctional oxygen reduction/evolution reaction (ORR/OER) electrocatalysts for Zn-air batteries, but the dynamic changes of transition metal oxides and the interface during catalysis are still unclear. Here, bifunctional electrocatalyst of Co─Co₂Nb₅O₁₄ is reported, containing lattice interlocked Co nanodots and Co₂Nb₅O₁₄ nanorods, which construct a strong metal-support interaction (SMSI) interface. Unlike the recognition that transition metals mainly serve as ORR active sites and metal oxides as OER active sites, it is found that both ORR/OER sites originate from Co₂Nb₅O₁₄, while Co acts as an electronic regulatory unit. The SMSI interface promotes dynamic electron transfer between Co/Co₂Nb₅O₁₄, and the reversible active sites of Nb⁴⁺/Nb⁵⁺ realize bidirectional adsorption/migration of intermediates, thereby achieving dynamic reversible interface reconstitution. The electrocatalyst shows a high ORR half-wave potential of 0.84 V, a low OER overpotential of 296.3 mV, and great cycling stability over 30000 s. The ZAB shows a high capacity of 850.6 mA h·gZn^-1 and can stably run 2050 cycles at 10 mA·cm⁻². Moreover, the constructed solid-state ZAB also shows leading cycling stability in comparison with the previous studies.