To improve the CO
2-reforming performance of TiO
2 photocatalyst, various metals were supported by means of photodeposition on coated TiO
2 film prepared by sol-gel and dip-coating method, and CO
2-reforming performance of such coated TiO
2 film was evaluated. When Pd was supported on the surface of coated TiO
2 film on Cu tube, the effect of the supported metal was not fully realized, because the coated TiO
2 film was separated from the Cu tube by embrittlement in the process of supporting the metal. When the coated TiO
2 film was prepared by dissolving TiO
2 powder with the supported metal in TiO
2 sol solution, the CO
2-reforming performance of coated TiO
2 film with Pd supported on TiO
2 powder was the highest among coated TiO
2 films with Cu, Pd or Pt supported on TiO
2 powder. The performance of reforming a gaseous mixture of CO
2 and H
2O into CO and hydrocarbon was promoted by decreasing firing time from 420 s to 180 s irrespective of supported metal type. With the aid of supported metal, the concentration of produced CO, the intermediate in the production of CH
4, increased with the concentration of produced CH
4, resulting in improved CO
2-reforming performance of coated TiO
2 film.
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