The Preparation Of Titanium Dioxide Nanobelts/Nanowires And Their Photocatalytic Properties

Semiconductor photocatalytic technology has attracted a wide attention for its outstanding advantages in environmental protection and water treatment. TiO₂ is one of the commonly used semiconductor photocatalyst due to a relatively higher light-harvesting efficiency and photoinduced electron transfer rate. However, its practical application is limited by several factors, for example, low quantum efficiency, wide band gap, as well as hard to recovery for suspension system. Therefore, it is of great importance to develop the supported TiO₂ photocatalyst with easy to recycle, high efficiency and sensitivity to visible light.In this paper, a series of TiO₂ nanobelts were successfully synthesized using the commercial TiO₂ powders（P25） as the raw material. Meanwhile, TiO₂ nanowires were prepared using Ti foil as the raw material. The as-prepared TiO₂ nanobelts/nanowires were modified with Ag metals. The samples were characterized using different detection methods including TG-DSC, XRD, SEM, UV-Vis etc. In addition, we comparatively studied the photocatalytic performance of samples, and discussed the growth mechanism of TiO₂ nanobelts/nanowires and the photocatalytic mechanism of the Ag modified TiO₂ nanobelts/nanowires membrane. Based on the above-mentioned experimentation, we can partly solve the problem such as the low solar energy utilization, difficulty in separation and recycle.（1） TiO₂ nanobelts were prepared successfully by hydrothermal method using commercially TiO₂ nanometer powders（P25） as the raw materials. A rational growth mechanism of nanobelts has been proposed according to nanobelts’ morphological variation obtained by adapting the concentration of NaOH. The experimental results show that the photocatalytic performance of TiO₂ nanobelts significantly decline compared to the P25 which can be attributed to the decrease of specific surface area though they can solve the difficulty in separation and recycle.（2） TiO₂ nanowires membranes were prepared by using the three-step method with titanium plate as the titanium source. The optimal hydrothermal process parameters were obtained, that is 12 M NaOH, reaction in 210 ℃ for 12 h. The ion exchange process was carried out in 0.1 M HCl solution at 50 ℃ for 6 h then calcination at 650 ℃. The results show that the samples have strong response to ultraviolet light except visible light.（3） Photoreduction was used to prepare Ag surface modified TiO₂ nanowires membranes. The effect of different AgNO3 concentration on morphology, optical properties and light catalytic performance of Ag/TiO₂ nanowires membranes was discussed. It is found that the light absorption properties of Ag modified TiO₂ nanowires membranes have strong response to ultraviolet light and visible light. The photocatalytic degradation result of MO shows that the sample with Ag modified possesses higher photocatalytic efficiency both in ultraviolet and visible light.