Cobalt phosphide microsphere as an efficient bifunctional oxygen catalyst for Li-air batteries

An efficient bifunctional catalyst for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is highly desired for the application of rechargeable metal air batteries. Herein, urchin-like CoP microspheres have been synthesized by a facile hydrothermal method with cetrimonium bromide as soft template. In alkaline solution, the as-prepared CoP catalyzes the ORR with an onset potential of -0.11 V (vs. Ag/AgCl) and a potential gap of 62 mV compared with commercial Pt/C catalyst. Meanwhile, the CoP catalyst exhibits better OER activities than the commercial RuO2 catalyst. Interestingly, when employed as cathodic catalyst for Li-air batteries, the battery shows good discharge capacity of 2994 mAh g(-1) at 100 mA g(-1), high round-trip efficiency of over 90%, excellent rate capability and cycle stability of sustaining 80 cycles without any capacity degradation at a high discharge current density of 500 mA g(-1). (C) 2018 Published by Elsevier B.V.