| Today, the environmental problem is a major challenge faced by human society. In recent years, the technology using semiconductor material as the photocatalyst to degradate contaminants provides us with an effective way to control environmental pollution, and the photocatalytic technology can handle toxic and hazardous substances in the water to achieve the purpose of improving the ecological environment and resource utilization. Titanium dioxide and silica is the commonly used semiconductor materials. They have good photochemical properties, so they have good prospects in photocatalyst. Titanium dioxide is an N-type wide band gap semiconductor, It contains of three kinds of crystal forms, namely anatase, rutile and brookite, and their band gap are 3.4 eV,3.2 eV and 3.0 eV. In addition, Titanium dioxides also have good chemical stability, which are preferred as photocatalyst semiconductor material. Silica is an N-type wide band gap semiconductor, and its band gap is between 3.5 and 4.0 eV, which is wider than titanium dioxide. Silica mainly contains of orthorhombic and tetragonal structure which is also known as rutile. The conductivity of non-stoichiometric titanium oxide is higher than titanium dioxide, especially Magneli phase Ti4O7 that its conductivity is up to 1995 S/cm. In this experiment, we prepared the porous titanium dioxide and silica and obtained high specific surface area and strong light absorption properties, so as to improve the photocatalytic properties of the material. This paper carried out the following work:1. Monodisperse PMMA microspheres with diameters of 200 nm,240 nm,300 nm, 350 nm and 390 nm were synthesized. PMMA colloidal crystal templates were prepared by centrifugation and water bath drying at constant temperature. SnO2 sol was synthesized by sol-gel process, infiltrated into the PMMA templates by immersion technique. After drying and heating, the three-dimensional macroporous (3 DOM) SnO2 was obtained, while treated it with TiCl4 solution. The samples were characterized by XRD, SEM, Raman, XPS and UV-vis techniques. At the end, we use the SnO2-3DOM as a catalyst applied to the photodegradation of methylene blue (MB) and methyl orange (MO) in UV-visible light, we find that the SnO2-3DOM have a high photodegradation efficiency of MB up to 80% an hour later and the photodegradation efficiency of the SnO2-3DOM treated with TiCl4 solution was about 59% and the rate constants are 0.0251 and 0.0142; however the SnO2-3DOM almostly have no degradation of MO.2. TiO2 sol was synthesized by sol-gel process, infiltrated into the PMMA templates with diameters of 240 nm,300 nm,350 nm and 390 nm by immersion technique. After drying and heating, the three-dimensional macroporous TiO2 was obtained. The samples were characterized by XRD and SEM techniques. At the end, we use the TiO2-3DOM as a catalyst applied to the photodegradation of methylene blue. We find that TiO2-3DOM which the diameter of PMMA microspheres with diameters of 390nm have highest photodegradation efficiency of MB up to about 98.13% two hours later, and the rate constant is 0.0329.3. We prepared porous TiOx by reducing TiO2 three-dimensional macroporous materials in a hydrogen furnace at 1050℃ for 2 h, and the flow rate of hydrogen is 180 ml/L. The samples were characterized by XRD and SEM techniques. We found the prepared material of TiOx appears one-dimensional morphology, and the main phase is Ti9O17, additionally containing Ti4O7, Ti5O9, Ti7O13 and other non-stoichiometric titanium oxide. |
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