Photoassisted anodic electrodeposition of ceria thin films

This study investigated the effect of UV light irradiation on a Pt working electrode during the anodic electrodeposition of ceria (CeO2) thin films in an aqueous solution containing Ce3+. UV light irradiation on the Pt anode induced the formation of holes in the valence band of anodically preformed CeO2 nuclei, which serve as photoabsorbers. The resultant holes oxidized Ce3+ to CeO2 at the CeO2/Solution interface as well as at the bare Pt surface. That is, CeO2 itself acted as a sensitive layer for photoelectrochemical deposition. Although the current efficiency was reduced by the UV irradiation, the deposition amount and crystal size of CeO2 clearly increased as compared to the dark process. It was verified that the oxygen saturation of the electrolyte solution was also effective in enhancing the deposition. In this paper, the photoelectrochemical deposition mechanism of CeO2 is discussed in detail, and the positive effects of photoirradiation on film quality are demonstrated.