Ionic liquids as phosphorus sources for preparation of cobalt phosphide and multiple heteroatom-doped mesoporous carbon with high electrocatalytic activity toward oxygen reduction reaction

Abstract

There is growing interest in the research of electrocatalysts for oxygen reduction reaction (ORR), which is the key issue for the commercialization of zinc-air (Zn-air) battery. Except precious metal based electrocatalysts, heteroatom-doped carbon materials, as one promising catalyst, also show excellent catalytic activity for ORR. In this work, cobalt phosphide (Co2P) and nitrogen, fluorine and phosphorus co-doped mesoporous carbon is synthesized in one step by a phosphorus-containing ionic liquids assisted route. Owing to the synergy effect of Co2P and functionalized mesoporous carbon, the catalyst exhibits a high half-wave potential of 0.86 V (vs reversible hydrogen electrode) which is about 30 mV positive than commercial Pt/C, coupled with outstanding stability. At last, the discharge potential of the primary zinc-air battery based on this catalyst is 1.1 V at a constant current density of 50 mA cm−2 (150 mV higher than Pt/C electrode) while the capacity is about 800 mAh g−1Zn. At the same time, the superior power density is also realized for the zinc-air battery using this catalyst (180 mW cm−2).