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

Abstract

The unique CoS 2 @N-doped carbon hybrids with core-shell structure could effectively improve oxygen bifunctional catalysis for Zn−air batteries. • The ZIF-L (Zn,Co) template-sacrificing and two-steps pyrolysis synthesis method. • Unique CoS 2 @ N -doped carbon hybrids with core–shell structure and small-size pores. • The bifunctional oxygen catalyst with long-term stability for rechargeable Zn-air battery. 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 CoS 2 @ N -doped carbon (CoS 2 @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 CoS 2 nanoparticles, the unique core–shell structure and small-size pores, the optimal CoS 2 @NC-60 is demonstrated to exhibit excellent ORR- and OER- catalytic activity. In particular, the ORR of CoS 2 @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, CoS 2 @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 CoS 2 @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.