Ferromagnetic Transformation of α-Fe2O3 via Co Doping for Efficient Water Oxidation under Magnetic Field

The introduction of a magnetic field has great potential for enhancing oxygen evolution reaction (OER) performance, but it requires the catalyst to be ferromagnetic and there is a lack of understanding of the fundamental mechanisms. Herein, we achieved the transformation of non-ferromagnetic α-Fe2O3 into ferromagnetic Co0.14FeOx by Co doping. Compared to α-Fe2O3, the OER activity of Co0.14FeOx considerably increased under a magnetic field of 3000 Oe and is proportional to the magnetic field strength within a certain range. This can be ascribed to the external magnetic field enhancing the degree of the magnetic moment ordering of Co0.14FeOx, which improved electron spin polarization.