The sheet-like nano TiO2 particles were prepared by using hydrothermal method, and were characterized by X-ray diffraction（XRD）, infrared spectroscopy（IR）, and transmission electron microscopy （TEM）. It is found that the nanoparticle sizes and crystallinity increase with the increase of hydrothermal temperature from 150 ℃ to 160 ℃, and then to 180 ℃. With the increase of particle sizes, the absorption capacities and photocatalytic abilities of as-prepared TiO2 particles for crystal violet become better and better. The nano TiO2 with big particles is more stable than that with small particles, although its initial photocatalytic activity is relatively lower compared with that of the small particle samples.
The Ag particles were photodeposited on TiO2 powder surface. The X-ray diffraction （XRD）, Raman spectroscopy, transmittance electron microscopy （TEM）, UV-vis diffused reflection spectroscopy （DRS）, X-ray photoelectron spectroscopy （XPS）, and photoluminescence （PL） spectrophotoscopy were used to investigate the structure and morphologies of the samples. It is found that the loaded Ag particles have no effect on the XRD patterns, and the Raman scattering becomes much stronger due to the surface Raman enhancing effect. The TEM images show that the TiO2 grains are in the shape of short sticks, and the spherical Ag particles with hexagonal structure are adhered to the TiO2 grain surface tightly. XPS result shows that the loaded Ag particles can not affect the chemical states of Ti and O, and they are mainly in the form of metal Ag. A wide plasmon absorption appears on the UV-vis spectra after Ag photodeposition. The loaded Ag further greatly decreases the PL intensity, which partly indicates the electron transfer from TiO2 to Ag. The photocatalytic activities firstly increase with the content of loaded Ag, and then sharply decrease. Finally, the photocatalytic mechanism related to Ag-loaded TiO2 powders was discussed in detail.
