The optical, structural and photoelectrochemical characteristics of porous hematite hollow spheres prepared by DC magnetron sputtering process via polystyrene spheres template

Porous hematite (α-Fe₂O₃) hollow sphere structures have been fabricated on fluorine-doped SnO₂ (FTO) glass substrate by DC magnetron sputtering process via polystyrene spheres (PS) latex as templates. The influences of deposition time and PS template on optical, structural and photoelectrochemical characteristics have been investigated. The as-obtained samples after annealing in ambient atmosphere were analyzed by scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Raman spectra, UV-visible spectra and electrochemical analysis. After annealing, all samples revealed only hematite characteristics in the Raman spectra. TEM images confirmed the porous hollow sphere structures which deposited for 20 and 30 min via PS templates. Based upon our observations, the porous α-Fe₂O₃ hollow spheres deposited for 30 min had a better photoelectrochemical performance with photocurrent density of about 1.4 mA/cm² at 0.6 V vs. SCE. This value was about 3 times higher than the no modified film (reference sample). Observed higher photocurrent density was likely due to a hollow sphere structure and a suitable thickness causing a higher charge carrier concentration and a lower charge transfer resistance.