CoSe2/Co nanoheteroparticles embedded in Co, N co-doped carbon nanopolyhedra/nanotube as efficient oxygen bifunction electrocatalyst for Zn-air batteries
Transition metal selenide-based materials have been demonstrated as one of the promising electrocatalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), yet the design of high efficient and stable electro-catalyst still remains a long and arduous challenge. Herein, a predesigned hybrid Zn/Co zeolitic imidazole framework is used to fabricate CoSe2/Co nanoheteroparticles embedded within hierarchically porous Co, N co-doped carbonnanopolyhedra/nanotube (CoSe2/Co@NC-CNTs) through facile one take measure of controlled carbonization and selenization procedures.As expected, the optimized CoSe2/Co@NC-CNT-1 displays outstandingelectrocatalytic performance in ORR and OER, with an onset potential of 0.95 V vs. RHE, a half-wave potential of 0.84 V vs. RHE for ORR and a potential of 1.69V vs. RHE for OER at 10 mA cm-2. It also exhibits excellent long-term stability and methanol resistance ability, which are superior to commercial 20 wt% Pt/C catalyst. Notably, the assembled Zn-Air battery with CoSe2/Co@NC-CNT-1 shows a low charge-discharge voltage gap (0.696 V at 10 mA cm-2) and high peak power density (100.28 mW cm-2) with long-term cycling stability. These superior performances can be ascribed to the synergistic effects of the highly active CoSe2/Co nanoheterostructure, hierarchically porous structure with large surface area, high electrical conductivity and uniformdoping of Co and N.