Tailoring the Electrochemical Hydrogen Evolution Activity of Cu3P through Oxophilic Surface Modification

•The surface oxophilicity of Cu3P is tuned by a simple electrochemical oxidation.•Hydrogen evolution with 160 mV overvoltage at 10 mAcm−2 in alkaline medium.•A net gain of 90 mV was obtained at a current density of 10 mAcm−2.•Cu3P displays a stable activity in alkaline medium over 24 hours.