Synergistically enhancing electrocatalytic activity of Co2P by Cr doping and P vacancies for overall water splitting

Designing high-performance and earth-abundant bifunctional catalysts for electrocatalytic water splitting remains a great challenge. Herein, a novel electrode composed of Cr-doped Co2P with P vacancies nanowire arrays (denoted as CrCo2P(Vp) NWs) grown on nickel foam was fabricated via a hydrothermal and successive calcination method. The Cr doping and vacancy engineering synergistically enable the exposure of more active sites, optimize electronic structure, and accelerate the charge transport capability, thus enhancing the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performances. As a result, the obtained Cr0.4Co2P(Vp) NWs catalyst exhibits superior catalytic activities in 1.0 M KOH solution with low overpotentials of 37 mV at −10 mA cm−2 for HER and 253 mV at 20 mA cm−2 for OER, respectively. Furthermore, using Cr0.4Co2P(Vp) NWs as a dual-function catalyst only requires 1.54 V voltage at 10 mA cm−2 for overall water splitting. Notably, the Cr0.4Co2P(Vp) NWs catalyst displays satisfactory stability with only a small attenuation of 3.2% after 50 h in a constant current testing. This study highlights the synergistic effect between doping and anion-vacancies in the enhancement of electrocatalytic activities and provides a feasible strategy to design effective, earth-abundant, and stable bifunctional electrocatalysts for water splitting.