The Preparation And Application Of Metal-oxide(SnO₂,La₂O₃) Sensing Materials

As a research focus of science and technology, metal-oxide semiconductor sensors have been investigated several dozens years. However, improving gas-sensing properties has been a pursing goal. Recently, doped or functional of conventional sensing materials or synthesized new-style sensing materials have provided new power for the development of sensors.Herein, Ce-doped SnO2 thin films and macroporous SnO₂ thin films have been prepared. In order to obtained high-performance sensors, the gas-sensing properties of SnO₂ thin film were investigated in detail. Moreover, one kind of novelty morphology Au modified cocoon-like La2O3 sensing nanomaterials were synthesized and applied in cataluminescence sensor for the detection of volatile organic compounds. The main contents are summarized as follows:1. Different concentrations of Ce-doped SnO₂ thin films were fabricated via the sol-gel method and dip-coating technique. Furthermore, the influencing factors of gas-sensing properties for butanone, such as cerium concentration, calcination temperature, the layers of thin films and humidity, were investigated. The results indicated that four-layer 1 at% Ce-doped SnO2 thin films calcined at 500 ?C presented the best response to butanone. At the optimal working temperature of 210 ?C, the response to 100ppm of butanone vapor was about 181 in dry air. The gas-sensing results showed that the approach of doping cerium had greatly improved the gas-sensing response and decreased the working temperature. Most importantly, the gas sensor presented selective response to butanone among all investigated gases. Accordingly, the gas sensors based on 1 at% Ce-doped SnO2 thin films have a promising application for the detection of butanone in practical security inspection environment.2. Macroporous SnO₂ thin films sensor was prepared using carbonaceous nanospheres as templates and sol-gel method. The thin films were made up of compact macroporous and nanoporous structure with lager specific surface area. The gas-sensing properties result showed that macroporous SnO2 thin films exhibited better response to ethanol, acetone, tetrahydrofuran and butanone, compared with common SnO2 thin films. Moreover, the gas sensor showed good selectivity, low detection limit, short response and recovery times. 3. One kind of novelty morphology cocoon-like La(OH)₃ precursor enlaced by nanowires were prepared by a simple hydrothermal method using oxalic acid as soft template. The influencing factors of morphology were researched, such as reaction temperature, reaction time, the molar of NaOH and oxalic acid. After modified by gold nanoparticles using ultraviolet irradiation method and calcined, the Au/La2O3 nanomaterials which exhibited good cataluminescence signals were obtained. For the detection of volatile organic compounds, such as acetone, tetrahydrofuran, ethanol, butanone, benzene, chloroform, chlorobenzene, the Au/La2O3 cataluminescence sensor showed stronger intensity compared with pure La2O3 nanomaterials. Accordingly, the gas sensors based on cocoon-like Au/La2O3 nanomaterials have a promising application for the detection of volatile organic compounds and persistent organic pollutants in environmental protection.