Studies on anion-induced structural transformations of iron(III) (Hydr)oxide micro-nanostructures and their oxygen evolution reaction performance

Herein, the fundamental studies on the influence of anions, NO3− and SO42−, on the formation of nanostructured α-Fe2O3 and α-FeOOH has been reported. Interestingly, the nitrate (NO3−) endows the formation of α-Fe2O3 while sulphate (SO42−) endows the formation of α-FeOOH. Thus, the prepared α-Fe2O3 and α-FeOOH were systematically characterized by using powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) and Fourier transform infrared spectroscopy (FT-IR). The SEM image reveals α-Fe2O3 and α-FeOOH were composed of microspheres and nanorods respectively. Further, the prepared α-Fe2O3 microspheres and α-FeOOH nanorods were used as potential electrocatalyst to catalyse oxygen evolution reaction (OER) where α-FeOOH nanorods were recognized as best OER catalyst with low overpotential of 333 mV at 10 mA cm−2 and stability over 20 h.