In-situ growth of CoNi bimetal anchored on carbon nanoparticle/nanotube hybrid for boosting rechargeable Zn-air battery

Exploring highly efficient non-precious metal based catalysts for bifunctional oxygen electrode is crucial for rechargeable metal-air batteries. In this study, with MOFs as precursors, a facile coprecipitation method is designed to realize in-situ growth of the CoNi anchored carbon nanoparticle/nanotube (CoNi/N-CNN) hybrid, which can achieve the simultaneous maximum exposure of both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) active centers. Benefiting from the unique structure, the CoNi/N-CNN catalyst exhibits excellent electrocatalytic performance for ORR (Eonset = 1.183 V, E1/2 = 0.819 V) and a low operating voltage of 1.718 V at 10 mA cm−2 (Ej=10) for OER. Delightfully, the home-made rechargeable Zn-air battery with CoNi/N-CNN delivers a high discharge power density up to 209 mW cm−2, and an outstanding charge–discharge cycling stability. The boosted bifunctional electrocatalytic activity can be ascribed to the strong coupling effect between Co/Ni center sites and defect-rich N-anchored carbon featured with porous and nanotube structure, which can introduce uniformly dispersed active sites, tailored electronic configuration, superb conductivity and convenient charge transfer process. The hybrid non-precious bimetal based electrocatalyst provides the possibility to develop the low-cost and high-efficient ORR/OER bifunctional electrocatalysts in rechargeable metal-air battery.