Preparation and characterization of composite semiconductor photocatalyst Cu/MoO3-TiO2

The composite semiconductor MoO3-TiO2 was prepared by sol-gel method and a new type Cu/MoO3-TiO2 photocatalyst was prepared by an isovolumetric impregnation method. The surface structure, particle size and photoabsorption performance of the catalyst were characterized by X-ray diffraction (XRD), laser Raman spectroscopy ( LRS), temperature- programmed reduction (TPR), infrared spectroscopy ( IR), transmission electron microscopy (TEM) and ultraviolet- visible diffuse reflectance spectroscopy (UV-Vis DRS). The results showed that the supporting of MoO3 on bulk TiO2 restrained the increase of TiO2 crystal diameters and its change from anatase to rutile. The average particle size of the catalyst was 10 similar to 20 nm and MoO3 dispersed on the TiO2 support surface with one monolayer of non-crystalline phase. The dispersion threshold value of MoO3 on TiO2 support was 10 %. The blue shift of photoabsorption edges was observed clearly after the addition of MoO3 on the TiO2 surface. The crystallite MoO3 appeared and the photoabsorption performance decreased when the MoO3 amount was more than the dispersion threshold. The formation of Mo-O-Ti bonds in the catalyst promoted the transfer of photo-generated current carriers between MoO3 and TiO2. Loading of metal Cu on the composite semiconductor MoO3-TiO2 improved the transformation from the tetrahedrally coordinated Mo species to the octahedrally coordinated Mo species.