Co2P/CoP hybrid as a reversible electrocatalyst for hydrogen oxidation/evolution reactions in alkaline medium

Due to the rapid development of alkaline polymer electrolyte fuel cells and water splitting, it is becoming increasingly urgent to develop non-precious metal electrocatalysts for the hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) in alkaline medium. Herein, Co 2 P/CoP hybrid is synthesized from cobalt carbonate hydroxide (CoCH) precursor, and further evaluated for the electrocatalytic HOR and HER in alkaline electrolytes. Specifically, benefiting from the reasonable hybrid structure that integrate suitable hydrogen adsorption energy of CoP and excellent conductivity of Co 2 P, Co 2 P/CoP hybrid exhibits excellent catalytic activities. The Co 2 P/CoP@NF hybrid has impressive HER activity, with a current density of −10 mA cm −2 at the overpotentials of −61 mV and the Tafel slope of 55.1 mV dec −1 , which can compete with recently reported transition metal phosphides and cobalt-based catalysts. In addition, the exchange current density of Co 2 P/CoP@NF hybrid is ~ 0.82 mA cm −2 for HOR, which is close to commercial Pt/C catalyst (~1.14 mA cm −2 ).