Unveiled Performance of Iron-Based Phosphates as Precatalysts for Oxygen Evolution Electrocatalysis

Iron (Fe)-based phosphates are identified as efficient precatalysts, which can be electrochemically transformed into highly active electrocatalysts for the anodic oxygen evolution reaction (OER) in water splitting. The OER performances of the electrochemically generated Fe-based compounds surpass those of the most active Fe-based multimetal oxides and any previously reported crystalline OER electrocatalysts; i.e., the OER-specific activity of the generated electrocatalyst from Fe3O3(PO4) at 1.55 V is 2-fold higher than that of the best conventional catalyst. Postcharacterization of the catalyst layer revealed that Fe3O3(PO4) was presumably transformed to Fe-based (oxyhydr)oxides with phosphorus dissolution.