Preparation of TiO2-MoO3 nano-composite photo-catalyst by supercritical fluid dry method

A series of TiO2-MoO3 nano-composite photocatalysts were prepared by supercritical fluid dry method (SCFD) and an impregnation technique with TiCl4 and (NH4)6Mo7O24.4H2O as the starting materials. The catalysts were characterized by the means of XRD, TEM and UV-Vis. Methyl orange was used as model compound for the evaluation of their catalytic activities. The results indicated that the photo-catalyst prepared by SCFD had the advantages of small size (12.84 nm), narrow distribution and good dispersivity. The presence of small amount of Mo in composite catalyst gives rise to the red shift of its absorbance wavelength, decrease of its energy gap and increase of the utility of visible light. Furthermore, higher surface acidity of the photo-catalyst was obtained as the result of the addition of MoO3. Compared with pure TiO2, the catalytic activity of the TiO2-MoO3 nano-composite photo-catalyst was improved significantly. As the doping concentration of the composite catalysts was controlled at 0.6% (molar percentage), 100% degradation of methyl orange was achieved with in 1.2 h irradiation time.