Electrosynthesis of copper phosphide thin films for efficient water oxidation

A copper phosphide (Cu ₃ P) thin film is synthesized on a Ni foam using a one-step electrodeposition method at room temperature and annealed at 300 °C in Ar atmosphere. The Cu ₃ P film is amorphous and has a flat morphology with surface voids. It works as an electrocatalyst for water oxidation in an alkaline 1 M KOH electrolyte. It exhibits excellent catalytic oxygen evolution reaction with an overpotential of 310 mV, Tafel slope of 88 mV/dec, and good stability over 20 h of operation at 10 mA/cm ² . The excellent OER performance is due to its large electrochemically active surface area and low charge transfer resistance at the catalyst-electrolyte interface after the annealing.