A comparative study on the microstructural feature and band-gap value of FeOOH and α-Fe2O3 films electrodeposited at different temperatures

The morphology, microstructural and optical properties of electrodeposited FeOOH and α-Fe2O3 films were characterized using scanning electron microscopy, X-ray crystallography, Raman spectroscopy, and UV–Vis spectroscopy. The results showed that the chemical composition of as-deposited films is FeOOH which will be transformed into α-Fe2O3 with higher degree of crystallinity by heat treatment process. The increase in electrodeposition temperature results in the formation of films with coarser morphologies (including aggregated equiaxed particles), Such films have larger grain size and lower band gap values in comparison to those that were electrodeposited at lower bath temperatures. The highest average particle size, degree of crystallinity and lowest band-gap value exhibited by α-Fe2O3 films electrodeposited at bath temperature of 70 °C.