Preparation And Photocatalytic Degradation Performance Of TiO₂ Based Hybrid Photocatalysts

Photocatalytic technology based on semiconductor catalysts provides an effective and environmental friendly solution to today's serious water pollution of organic substances. TiO₂ attracts considerable interest in photocatalytic researches because it is non-toxic, cheap, easy to get, chemically stable, and powerful in deep oxidation. However, its large band gap, low quantum efficiency, and difficulty in recycling restrict its wide application in industry. Focusing on the above problems, we synthesized reduced graphene oxide modified ultra-long TiO₂ nanotube and TiO₂ nanowire array film. It can reduce the recombination probability of photo-induced electrons and holes because of the excellent electron conductivity of reduced graphene oxide. On the other hand, AgCl nanoparticles were anchored on the surface of TiO₂ microspheres to improve the photoresponse ability to visible light. Analysis methods such as XRD, SEM, FTIR, DRS, BET et al. were used to study the structure and property of the composite photocatalyst. The organic dye Rhodamine B and methyl orange were photodegraded to evaluate the photocatalytic activity of the composite photocatalyst.The main results and conclusions in this study are summarized as following:?1? The ultra-long titanate nanotube was synthesized by stirring hydrothermal method and its growth process was studied. Then the titanate nanotube was mixed with graphene and vacuum annealed to make ultra-long TiO₂ nanotube/reduced graphene oxide composite photocatalyst. The results show that the photocatalytic activity of the composite photocatalyst with 3% reduced graphene oxide reaches the maximum and the photodegradation rate is 2.2 times of the pure TiO₂ nanotube.?2? The reduced graphene oxide/TiO₂ nanowire arrays film was achieved using dipping method, voltage deposition, and thermal evaporation apparently, all followed by argon annealing. The composite film synthesized by thermal evaporation has the best photocatalytic activity, and the degradation rate is 2.9 times of the pure TiO₂ nanowire arrays film. Furthermore, the photocatalytic activity of the TiO₂ nanowire arrays film increases with the increasing of reduced graphene oxide but an excess of reduced graphene oxide leads to a decrease of photocatalytic activity.?3? AgCl nanoparticles were adhered onto the surface of TiO₂ microspheres by ion exchange method to synthesis AgCl/TiO₂ microspheres plasmonic photocatalyst. The maximum photocatalytic activity was achieved when the sample was heated at 400 °C. After 150 min illumination, 96.4% methyl orange could be degraded by composite photocatalyst with 400 °C treatment, while only 34.1% methyl orange can be degraded by Ag/AgCl.