Engineering Ni3+ inside nickel selenide as efficient bifunctional oxygen electrocatalysts for Zn–air batteries

Abstract

Developing a high-efficienct, low-cost and stable non-noble-metal-based bifunctional electrocatalyst for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) as oxygen electrode material in the rechargeable zinc–air battery is crucial in renewable energy conversion technologies. In this work, nitrogen-doped hollow carbon sphere (NHCS) decorated with various nickel selenide (NixSe) nanoparticles had been designed and successfully prepared. Among them, the Ni0.85Se–NHCS with the highest percentage of Ni3+ could serve as a new efficient bifunctional electrocatalyst toward ORR/OER (with an onset potential of 0.850 V for ORR and a potential of 1.583 V at 10 mA·cm−2 for OER) in an alkaline medium. Furthermore, the assembled Zn–air battery coupled with Ni0.85Se–NHCS electrode has excellent discharging–charging performance and long lifetime. This work provides a valuable understanding on transition metal non-oxide electrocatalysts and expands the applications of selenide-based materials.