CoS2 nanoparticles-embedded N-doped carbon hybrid derived from ZIF-L as bifunctional oxygen electrocatalysts for rechargeable Zn-air batteries

Zeolitic imidazolate frameworks (ZIFs) with controllable tunability of compositions and morphologies are identified as efficacious self-sacrificial precursors to prepare functionally-oriented nanostructured materials. Pressingly, we urgently need to use highly efficient bifunctional oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) electrocatalysts for the enhancement of rechargeable metal air batteries research. Herein, the unique CoS2@N-doped carbon (CoS2@NC-X) hybrids are successfully achieved via direct calcination and sulfurization of 2D leaf-like bimetallic imidazole framework (ZnCo-ZIF-L). Owing to the synergic effect between intrinsic activity of CoS2 nanoparticles, the unique core-shell structure and small-size pores, the optimal CoS2@NC-60 is demonstrated to exhibit excellent ORR- and OER- catalytic activity. In particular, the ORR of CoS2@NC-60 not only possesses a half-wave potential of 0.84 V (compared to RHE), but also has a limiting current density of 5.18 mA cm-2. Furthermore, CoS2@NC-60 possesses an overpotential (compared to RHE) of 350 mV required to drive the current density of 10 mA cm-2. As a validation, the CoS2@NC-60 catalyst is intended for use in rechargeable Zn-air batteries, where it has the outstanding long-term stability (550 h) and an exceptional power density (170.6 mW cm-2). This facile synthetic strategy renders a feasible way to further probe non-noble metal electrochemical catalysts.