Comparison of CO(2) Reduction Performance with NH(3) and H(2)O between Cu/TiO(2) and Pd/TiO(2)

The aim of this study is to clarify the effect of doped metal type on CO(2) reduction characteristics of TiO(2) with NH(3) and H(2)O. Cu and Pd have been selected as dopants for TiO(2). In addition, the impact of molar ratio of CO(2) to reductants NH(3) and H(2)O has been investigated. A TiO(2) photocatalyst was prepared by a sol-gel and dip-coating process, and then doped with Cu or Pd fine particles by using the pulse arc plasma gun method. The prepared Cu/TiO(2) film and Pd/TiO(2) film were characterized by SEM, EPMA, TEM, STEM, EDX, EDS and EELS. This study also has investigated the performance of CO(2) reduction under the illumination condition of Xe lamp with or without ultraviolet (UV) light. As a result, it is revealed that the CO(2) reduction performance with Cu/TiO(2) under the illumination condition of Xe lamp with UV light is the highest when the molar ratio of CO(2)/NH(3)/H(2)O = 1:1:1 while that without UV light is the highest when the molar ratio of CO(2)/NH(3)/H(2)O = 1:0.5:0.5. It is revealed that the CO(2) reduction performance of Pd/TiO(2) is the highest for the molar ratio of CO(2)/NH(3)/H(2)O = 1:1:1 no matter the used Xe lamp was with or without UV light. The molar quantity of CO per unit weight of photocatalyst for Cu/TiO(2) produced under the illumination condition of Xe lamp with UV light was 10.2 μmol/g, while that for Pd/TiO(2) was 5.5 μmol/g. Meanwhile, the molar quantity of CO per unit weight of photocatalyst for Cu/TiO(2) produced under the illumination condition of Xe lamp without UV light was 2.5 μmol/g, while that for Pd/TiO(2) was 3.5 μmol/g. This study has concluded that Cu/TiO(2) is superior to Pd/TiO(2) from the viewpoint of the molar quantity of CO per unit weight of photocatalyst as well as the quantum efficiency.