Fabrication of shape-controlled α-Fe₂O₃ nanostructures by sonoelectrochemical anodization for visible light photocatalytic application

In this study, various α-Fe₂O₃ (hematite) nanostructures were prepared on Fe foils by sonoelectrochemical anodization method. The principal component of the electrolyte was ethylene glycol contained 0.3 wt.% NH₄F. The α-Fe₂O₃ surface shapes have been controlled by varying the water volume ratios (WVR) in electrolyte solution. The α-Fe₂O₃ samples were characterized by field emission scanning electron microscopy, energy-dispersive x-ray spectroscopy, grazing incidence x-ray diffraction, and UV-vis absorbance spectra. As the variation of WVR, the α-Fe₂O₃ samples showed different surface morphologies of nanoparticles, nanorods, nanoporous, and nanoleaflets. The visible light photocatalytic activity of the α-Fe₂O₃ nanostructures was investigated by degradation of methylene blue, and the α-Fe₂O₃ nanoporous sample showed the best photocatalytic performance.