Electrophoretic deposition films, crystal structures, optical properties, and photocatalytic activities for double-perovskite oxide Ba \(_{2}\) Ce(Bi \(_{1-x}\) Sb \(_{x}\) )O \(_{6}\) were demonstrated. Photocatalytic oxide films of Ba \(_{2}\) Ce(Bi,Sb)O \(_{6}\) were synthesized by electrophoretic deposition technique from fine powder samples. The parent sample crystalized in a monoclinic single-phase structure. For the intermediate and end-member samples, multiple phases accompanied by monoclinic and cubic structures were stabilized in our preparation technique. X-ray photoelectron spectroscopy measurements on the x = 0.0 and 1.0 powder samples were performed, to examine the valence state of B-site cations. Indirect bandgap energies were estimated to be 0.80 eV at x=0.0 and 2.82 eV at x=1.0 from optical spectrum measurements through Kubelka–Munk transformation. These findings were well explained by band structures on the basis of density functional theory. We revealed that the band structures, crystalline sizes, and multivalent B-site cations play a significant role in the observed photocatalytic improvements. Photocatalytic performances of Ce-based deposition thick films were discussed in comparison with their properties of powder samples.
