Zn/CoP polyhedron as electrocatalyst for water splitting and Zn-air battery

Abstract

High efficient electrocatalytic activity towards oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are very critical to renewable energy technologies such as water splitting、rechargeable Zn-air battery. As a promising class of catalysts, the transition metal phosphide that are considered as promising substitutes to noble metal based catalysts. In this work, the N-doped polyhedral Zn/CoP porous material was obtained by high-temperature pyrolysis of Zn/ZIF67 as precursor. The optimized Zn/CoP sample possessed outstanding bifunctional activity of OER and HER in 1 M KOH, it also possesses HER activity in 0.5 M H2SO4. The Zn/CoP electrode with meso/macropores can act as both an anode and a cathode to fabricate an electrolyzer for overall water splitting, it was able to achieve a current density of 10 mA cm−2 at a cell voltage of 1.41 V with remarkable stability. Meanwhile, the corresponding rechargeable Zn-air battery based on Zn/CoP air cathode also exhibit an open circuit voltage of 1.43 V, low charge-discharge voltage gap (0.96), high power density (93.6 mW cm−2), and strong cycle stability, making it a suitable alternative to take the place of precious metal catalysts for practical utilization.