Phosphorous-doped carbon coordinated iridium diphosphide bifunctional catalyst with ultralow iridium amount for efficient all-pH-value hydrogen evolution and oxygen reduction reactions

Abstract

Ultralow noble metal loading catalyst is one of the current main research trends for hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR). In this context, we synthesize the phosphorus-doped carbon covered IrP2 catalysts (IrP2@PC) with Ir amount merely about 1 wt% by an extremely simple way. It possesses remarkably high HER performance, exceeding commercial Pt/C and most reported transition metal catalysts in the whole pH range. In alkaline electrolytes, it shows an ultralow overpotential of 10 mV at a current density of 10 mA·cm−2, almost 100% Faradaic yield for hydrogen production, and continuous discharge stability for more than 10 h. At the same time, in acidic and neutral electrolytes, its overpotentials at the same current density are as low as 15 and 32 mV, respectively. Interestingly, linear Sweep Voltammetry (LSV) data present that, under alkaline conditions, IrP2@PC also possesses a half-wave potential of 0.81 V, extremely close to commercial Pt/C catalysts, indicating that the catalyst also possesses outstanding ORR performance.