Synergistic effect of nitrate content and ethanol on photo-assisted anodic deposition of ceria thin films

Nanocrystalline ceria thin films have been prepared by photo-assisted anodic deposition in two kinds of solutions (water and 70% v/v ethanol-water) containing different sodium nitrate concentrations (0, 0.15, 0.20, 0.25 and 0.30 mol l− 1) onto 316L surface. The synergistic effect of nitrate content and ethanol on the formation of ceria films was studied with scanning electron microscopy, ellipsometry, X-ray diffraction, and Raman, UV-visible, and X-ray photoelectron spectroscopy. Results show that the current density, film thickness, particle size and Ce(IV) content increase with increasing nitrate concentration in water solution whereas decrease in 70% v/v ethanol-water solution. When the nitrate concentration is higher than 0.25 mol l− 1, the positive function of nitrate on the growth of ceria films is more prominent than ethanol. The action mechanism of nitrate on the photoelectrochemical deposition of CeO2 in two different solutions has been discussed in details.