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.