Study On Synthesis And Performance Of TiO₂ Composites

Energy crisis and environmental pollution has become a global issue demanding prompt solution. Photocatalytic degradation technology as one of the measures for environmental pollution, will be to take advantage solar energy into chemical energy and high density electrical energy in the temperate conditions, and can use sunlight directly catalytic degradation of organic pollutants in the air or water. Titanium dioxide（TiO₂） due to its high photocatalytic performance, high stability and non-toxic characteristics has become the most potential photocatalyst. However, TiO₂ have limitations in practical applications. First of all, the band gap energy of TiO₂ is 3.2 eV, only when it absorbs UV which wavelengths less than 380 nm it can show the catalytic activity, while in sunlight of solar spectrum UV accounted for only 3-5%; Second, low rates in electron transfer and high rates of electron-hole pair recombination. For this defect, this paper explore the synthesis methods and synthesis conditions of TiO₂ materials, doped with carbon nanotube（CNT）, carbon quantum dots（CDS） form a TiO₂ composite material to improve the photocatalytic properties and electrochemical properties of TiO₂ materials.1. Using one step high temperature thermal decomposition method, hydrothermal method and microwave hydrothermal method with different particle size and photocatalytic activity of TiO₂ photocatalyst materials. Then used these composite degradation to certain concentration of methyl blue, investigate the reaction temperature, reaction time on the material crystal structure, optical properties, specific surface area and the influence of the photocatalytic activity of different synthesis methods.Respectively to find out the optimum synthesis conditions of various synthetic methods. The results showed that both three synthesis methods can prepared anatase TiO₂, among them, using the hydrothermal method under the conditions of hydrothermal treatment temperature at 180 °C for 12 h TiO₂ reflect smaller particle size and the best photocatalytic activity.2. Different weight addition of TiO₂/CNT nano composites was prepared by hydrothermal method, their crystal structure and morphology characteristics were characterized. Through the degradation of organic pollutants- Sudan（I）, comparing the photocatalytic activity of the nano composites materials with pure TiO₂ materials. The composite with 0.3% CNT content showed the best catalytic activity, and its reaction activation energy was calculated as 39.54 kJ/mol from experimental rates. Half-life shorten from 9.82 to 3.81 minutes. The degradation products of Sudan（I） with different irradiation durations were characterized by Fourier transform infrared spectroscopy, and a degradation reaction process was proposed. Mean while, electrochemical performance of the best proportion nano composite material and the pure TiO₂ material also been tested.3. Different weight addition of TiO₂/CDS nano composite prepared by electrolytic method and hydrothermal method, their crystal structure and morphology characteristics were characterized. Through the degradation of organic pollutants- phenol, comparing the photocatalytic activity of the nano composites materials with pure TiO₂ materials. The composite with 0.5wt% CDS showed the best catalytic activity, and its reaction activation energy was calculated as 63.71 kJ/mol from experimental rates. Half-life shorten from 150.68 to 32.54 minutes. Mean while, electrochemical performance of the best proportion nano composite material and the pure TiO₂ material also been tested.