The Studies Of TiO₂ Nanoparticles And Their Composistes For The Photocatalytic Degradation Of Dihydroxybenzenes

nanomaterials are very important semiconductor nanomaterials during the photocatalytic reactions due to their excellent photocatalysis properties, and they have been widely used. However, because of the high photon-generated electron-hole recombination rate, the low quantum efficiency, their easy agglomeration, and the suspended photocatalysts are difficult to recycle, the practical applications of TiO2 nanomaterials are restricted severely.To solve these above problems, we have done a series of experiments to investigate TiO2 based nanomaterials and their precursors for the photodegradation of dihydroxybenzenes, the main contents are as follows:1. The TiO2 nanoparticles and their precursors were successfully synthesized using the hydrothermal and hydrolysis method, respectively. The morphology, structure and phase of the synthesized nanomaterials were characterized by TEM and XRD. The photocatalytic properties of TiO2 nanoparticles and their precursors were studied by the degradation of three types of dihydroxybenzenes in detail. These studies showed that the degradation rates of TiO2 nanoparticles and their precursors were obviously different. Referred to the previously literature and our experiment results, it was made clear that the interaction types between TiO2 nanomaterials (TiO2 nanoparticles and their precursors) and the three types of dihydroxybenzenes. And a catalytically molecular mechanism for different types of dihydroxybenzenes was also discussed in detail.2. The photocatalyst of TiO2/attapulgite composite was synthesized by hydrothermal treatment using the attapulgite as a carrier, and the morphology, structure and phase of the synthesized composite photocatalyst were characterized by TEM and XRD. The photocatalytic properties of the composite photocatalyst were studied by the degradation of three types of dihydroxybenzenes. And the degradation results were compared with the self-prepared anatase TiO2 nanoparticles and the commercial P25 TiO2 nanoparticles. These results showed that the photocatalytic ability of the self-prepared anatase TiO2 nanoparticles is better than the commercial P25 TiO2 nanoparticles, owing to the self-prepared TiO2 nanoparticles having smaller size. And the photocatalytic ability of the composite photocatalyst was inferior to the other two TiO2 nanoparticles because of the low recombination rate. However, this composite photocatalyst settled quickly and was favour for separating and recycling, so it still had values to the practical applications.3. The Au nanoparticles were reduced by sodium borohydride for chloroauric acid, and the photocatalyst of Au-TiO2/attapulgite composite was obtained by using the attapulgite as a carrier and loading Au nanoparticles. The morphology, structure and phase of the synthesized composite photocatalyst were characterized by TEM and XRD. The photocatalytic properties of the composite photocatalyst were studied by the degradation of three types of dihydroxybenzenes. These results showed that the TiO2 and the attapulgite were negatively charged because they were both rich in hydroxyl group, so they couldn't combine tightly. But when adding a cationic surfactant CTAB which was positively charged via the electrostatic interaction, they could combine more effectively. On the other hand, Au nanoparticles were also good catalysts, so after depositing Au nanoparticles, the photocatalytic ability of the composite photocatalyst was enhanced.