Constructing Stable Bifunctional Electrocatalyst of Co─CoNbO 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─CoNbO is reported, containing lattice interlocked Co nanodots and CoNbO 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 CoNbO, while Co acts as an electronic regulatory unit. The SMSI interface promotes dynamic electron transfer between Co/CoNbO, and the reversible active sites of Nb/Nb 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 and can stably run 2050 cycles at 10 mA·cm⁻. Moreover, the constructed solid-state ZAB also shows leading cycling stability in comparison with the previous studies.