Preparation Of In₂O₃-based Nanomaterials And Study Of NO₂ Gas Sensing Properties

As one of the main air pollution sources,NO₂,mainly comes from factory wastes,automobile exhaust emissions and fuel combustion by-products.According to data reported by the National Institute for Occupational Safety and Health（NIOSH）,chronic exposure to high levels of NO₂ can be a serious health hazard.Therefore,it is rewarding for the development of society and human health to create an efficient and convenient NO₂ sensor.In₂O₃,a typical n-type semiconductor with high conductivity and good physicochemical properties,has been widely used in recent years for the detection of NO₂ gas.In this paper,In₂O₃ based nanomaterials were prepared by solvothermal method and chemical precipitation method.The sensing mechanism of the sensor for NO₂ was verified by in-situ DRIFT testing.The research in this paper focuses on the following areas:（1）Hollow tubular In₂O₃gas sensor was synthesised by a simple solvothermal method using indium acetylacetonate as a raw material.The results show that the material had a response value of 812 for 5 ppm NO₂gas at the lower test temperature（92 ^oC）,a response time of 50 s and a recovery time of 39.4 s.（2）Flower-like Cl doped In₂O₃ gas sensing materials were prepared by ionic liquid-assisted synthesis,the response of the sensor to 5 ppm NO₂ was 425.9,and the recovery time was 69 s at 50 ^oC.In addition,the response/recovery curves of the material to NO₂gas and the in-situ DRIFT test under different atmospheres were used to verify the sensing mechanism of the material to NO₂gas under UV light.（3）In₂O_3-x（OH）_y nanoparticles were synthesised using a simple chemical precipitation method using In（NO₃）₃ as the reaction material,the sensing performance of the sensor for NO₂ was investigated.Compared to the previous two sections,the optimum test temperature was reduced to room temperature,with a response value of94.06 for 5 ppm NO₂gas at 25^oC,a response time of 20 s and a reduced detection limit of 50 ppb.In addition,the response mechanism of the sensor to NO₂ gas was further validated by in-situ DRIFT testing at room temperature.