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Abstract: Acetic acid (HAc) aqueous was used as solvent in wetness impregnation to prepare CeO2-modified γ-Al2O3 support. With the help of HAc, the dispersion of CeO2 on γ-Al2O3 is significantly improved and the size of CeO2 nanoparticles can be controlled through tuning the concentration of HAc aqueous. XPS analysis shows that the percentages of Ce3+ in CeO2 nanoparticles will vary with the size. Then we load CuO on the as-prepared CeO2-modified γ-Al2O3 support and choose NO reduction with CO as a probe reaction to investigate the influences of impregnation solvent on the catalytic properties. The results demonstrate that the CuO/CeO2/γ-Al2O3 prepared in the solvent with volume ratio of 20:1 (H2O:HAc) has the highest activity in NO+CO reaction. Combing the structural characterizations and catalytic performances, we think that the size of the CeO2 nanoparticles should be a key factor that affects the activities of CuO/CeO2/γ-Al2O3. Furthermore, CuO dispersed on CeO2 nanoparticles with an average size of ca. 5nm should be the highest active sites for NO+CO reaction. [Copyright &y& Elsevier]

Abstract: Titania hollow spheres were synthesized via the styrene-methyl methacrylate copolymer (PSMMA) spheres as templates in conjunction with the sol–gel method without any surfactant or polyelectrolyte. Uniform TiO2 hollow spheres were made up of loosely aggregated anatase-phase nanoparticles. Compared to TiO2 nanoparticles (NPs), TiO2 hollow spheres exhibited a higher photocatalytic activity for the degradation of methyl orange (MO), which may be attributed to their larger specific surface area, more abundant porous structure and larger band-gap energy. In addition, the hollow spheres catalysts can be recycled. [Copyright &y& Elsevier]