| Nano-sized titanium oxide (TiO2, titania) has been intensively investigated due to its outstanding physical and chemical properties in photocatalytic applications for the protection of the environment, such as wastewater treatment, and air purification. A number of investigations related to such photodegradation reactions have been carried out using suspensions of TiO2 powders in polluted aqueous solution. Unfortunately, some difficulties have been met in practical environmental applications using pure TiO2 powders. Recently much work has been carried out to immobilize TiO2 particles as thin films onto various substrates such as TiO2/AC, TiO2/zeolite and TiO2/pumice etc. It has been demonstrated that the light adsorption of the supporting materials play important role in determining photocatalytic degradation rates of several aqueous pollutants, and the surface morphology of the substrate materials including the particle shapes and arrangement, would greatly affected the properties of TiO2 thin films.In our early work, we have reported spikes-like silicon surface morphology induced by femtosecond laser pulses irradiation. Compared with unstructured silicon, the light absorption of the microstructured silicon (MS) was significantly enhanced, and the geometric structures on the silicon surface play an important role in the below-band gap enhanced light absorption. The remarkable optical properties of MS open up new possibilities for application in optoelectronic and detectors fields. In addition, the MS is a potential substrate of the thin films, due to its good characteristics of physical stability and greater surface areas. In the present work, the MS were used as a substrate for TiO2 thin films. We found that the photocatalytic activity of TiO2/MS composites could be greatly improved, which because of the MS shows larger surface areas is more effective in sorption of dye molecules and the spikes formed on the silicon surface improved the light utilization efficiency. |
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