Morphology Development And Gas Gensing/Electro-optic Properties Research Of Oxide Semiconductors

Environmental pollution and energy shortage are the two bottleneck problems which restrict the social and economic development of our country. In recent years, people's daily life and physical health has been seriously affected by the frequent ash haze pollution, which need to be controlled from the spurce. The main reason for the formation of ash haze is that Nitrogen Oxides?NOx?, Sulfur Oxide?SOx?, volatile organic compounds?VOC? and etc. will form the solid particles through atmospheric reaction in the air. Therefore, both real-time monitoring of the pollution gas concentration in the source and real-time and quick monitoring of the pollution gas in the air are very meaningful for the air pollution control and prediction.Gas sensor display a great potential application in pollution Sources Monitoring and atmospheric environment monitoring. Especially, gas sensors based on semiconductor oxides have the advantages of high response, tunable selectivity, high reliability, all solid state, small type and cheap price. So, it is a hot topic in the field of gas sensor study.On the other side, as the alternative energy of fossil energy and clean energy, the study of solar cell has received much concern. Among the various types of solar cell based on different principles, Dye-sensitized Solar Cell?DSSC? has the advantage of high theory efficiency, simple process, environmental friend, low price and etc., and it is also a hot topic in the field of photovoltaic study.In DSS, as the semiconductor oxides of photoanode, the microstructure/morphology will affect the photoelectric conversion efficiencies. Therefore, this thesis focused on the nanostructure of semiconductor oxides and systematically studied and designed the sensing/photoelectric properties through fulfillment of the controllable preparation. Self-assembly flower-like ?-Fe₂O₃ spheres and Co doped In₂O₃ nanofibers were prepared through a hydrothermal and electrospinning method respectively, and the gas sensing properties concerning these nanostructure was also studied; flower-like TiO₂ spheres was prepared through a hydrothermal method, and the photoelectric properties was investigated when it was made as photoanode. The detail research contents are as follows:?1?Flower-like ?-Fe₂O₃ was prepared and the gas sensing properties was evaluated: Fe Cl3·6H2O was used as the Fe source and polyvinylpyrrolidone?PVP? as the surfactant. The hydrothermal time was 12 h at 120?. Finally, through sintering at 600? for 2 h, pure flower-like ?-Fe₂O₃ could be obtained. The sintering tube type gas sensors based on the as-prepared materials was fabricated. The sintering condition was 400? for 2 h. The evaluation results indicated that the gas sensors based on the self-assembly bundle-flower-like ?-Fe₂O₃ exhibited high response to the target gas of acetone. The optimal working temperature is 200?, and the gas response was about 11.3 to 80 ppm acetone. Compared with commercial ?-Fe₂O₃ powder, the gas response has been obvious increased.?2? Co doped In₂O₃ nanofibers was prepared by electrospinning method, and the gas sensing properties were characterized: Indium nitrated was used as the In source, PVP and DMF was used as the solvent, and cobaltous acetate was used as the dopant to prepare the precursor solution of electrospinning. At the voltage of 16-22 k V, different Co doping nanofiber precursor was prepared. Through sintering at 500?. The experiment results indicated that the gas sensor had the highest response to acetone when the doping content of Co was 3%. The optimal working temperature is about 30 to 100 ppm acetone.?3?Flower-like TiO₂ nanospheres were synthesized through a hydrothermal method. The as-prepared materials was used as the photoanode of DSSC, and the effect of such structure to photoelectric conversion efficiency was investigated. Tetra-n-butyl titanate was used as Ti source, isopropanol as solvent, and diethylene triamine as the surfactant to prepare the precursor solution. Then, the solution was hydrothermally treated at 200? for 24 h. Finally, the precipitation was sintered at 450? for 2 h and pure flower-like TiO₂ nanomaterials could be obtained. When the final product was used as the photoanode of DSSC, the photoelectric conversion efficiency could be greatly improved compared with commercial P25?one kind of TiO₂ nanoparticles?.