Integration of partially phosphatized bimetal centers into trifunctional catalyst for high-performance hydrogen production and flexible Zn-air battery

The development of robust and efficient trifunctional catalysts showing excellent oxygen evolution reaction (OER), oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) kinetics has been challenging. Herein, we prepared a hybrid iron and cobalt-based metal alloy phosphide on a phosphorus and nitrogen co-doped carbon substrate (FeCo-P/PNC) as a catalyst using a one-step Pregulation method. The catalyst exhibited a positive half-wave potential of 0.86 V versus the reversible hydrogen electrode (RHE) for ORR, and low overpotentials of 350 and 158 mV for OER and HER, respectively, to achieve a current density of 10 mA cm^-2. Density functional theory calculations demonstrated the dominant role of P in both FeCo phosphide and carbon matrix, which led to the good ORR, OER and HER kinetics. The assembled aqueous and flexible Zn-air batteries with FeCo-P/PNC as the air cathode displayed excellent peak power densities of 195.1 and 90.8 mW cm–2, respectively, as well as outstanding charging-discharging performance, long lifetime, and high flexibility. Moreover, the self-powered overall water-splitting cell exhibited a low working voltage of 1.71 V to achieve a current density of 10 mA cm^-2, confirming its excellent multifunctional OER/ORR/HER activity. [Figure not available: see fulltext.]