Iron and Oxygen Codoped Cobalt Phosphide Solvothermally Prepared from a Metal–Organic Framework for Oxygen Evolution

The preparation of highly active and low-cost electrocatalysts is a major challenge for water electrolysis. Here, iron and oxygen codoped cobalt phosphide nanoparticles (O–Co1–xFexPy, x = 0–0.42) are prepared by reacting metal–organic framework with phosphorus under solvothermal conditions. When electrochemically catalyzing the oxygen evolution reaction (OER) in 1 M KOH, O–Co0.58Fe0.42Py supported on the nickel foam exhibits the best activity, with only 232 mV overpotential to reach 10 mA cm–2 OER current densities. O–Co0.58Fe0.42Py is robust toward the long-term OER, and surface phosphide layers transform to (oxy)hydroxides during the OER. O–Co1–xFexPy also shows better OER activity than Co3O4 nanoparticles and commercial IrO2. The abundant electrochemically active sites exposed by the highly porous morphology and the electron interactions between Co and Fe that accelerate the OER intermediate adsorption process could account for the observed high OER activity.