Photocatalytic reduction of carbon dioxide over Cu/TiO 2 photocatalysts

摘要

The photocatalytic reduction of CO~(2)with H~(2)O was investigated using Cu/TiO~(2)photocatalysts in aqueous solution. For this purpose, Cu/TiO~(2)photocatalysts (with 0.2, 0.9, 2, 4, and 6?wt.% of Cu) have been synthesized via sol-gel method. The photocatalysts were extensively characterized by means of inductively coupled plasma optical emission spectrometry (ICP-OES), N~(2)physisorption (BET), XRD, UV-vis DRS, FT-IR, Raman spectroscopy, TEM-EDX, and photoelectrochemical measurements. The as-prepared photocatalysts contain anatase as a major crystalline phase with a crystallite size around 13?nm. By increasing the amount of Cu, specific surface area and band gap energy decreased in addition to the formation of large agglomeration of CuO. Results revealed that the photocatalytic reduction of CO~(2)decreased in the presence of Cu/TiO~(2)in comparison to pure TiO~(2), which might be associated to the formation of CuO phase acting as a recombination center of generated electron-hole pair. Decreasing of photoactivity can also be connected with a very low position of conduction band of photocatalysts with high Cu content, which makes H~(2)production necessary for CO~(2)reduction more difficult.