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