Preparation Of Zinc Oxide And Indium Oxide Nanomaterials And Their Gas Sensitivity To NO

NO is an important atmospheric pollutant,mainly from industrial by-products and automobile exhaust emissions,which is the main cause of acid rain and ozone layer depletion.The regulations on occupational safety and health clearly indicate that more than 25 ppm will affect gene transcription,etc.NO can also damage mucous membranes and respiratory tract,causing harm to human body and environment.Therefore,it is very important to develop gas sensors with high sensitivity,selectivity and reliability for real-time monitoring of NO.Gas sensors play an important role in many aspects of today's society and have made great progress with the development of nanoscience and nanotechnology.The results show that gas-sensitive materials are the key to influence the performance of gas sensors.Metal oxide semiconductor?MOS?is the preferred material for gas sensors,such as ZnO,In₂O₃,SnO₂ and WO₃.They not only have high sensitivity,fast response,but also good stability and simple structure.However,to solve the problems in practical applications,metal oxide sensors also face some limitations,such as high operating temperature,long response and recovery time and poor selectivity.However,metal oxide based gas sensors face some limitations,improving the performance of sensors is still an urgent problem to be solved.In this paper,improving performance and reduce the reaction temperature sensor,taking zinc oxide and indium oxide as research objects,a simple and environmentally friendly solid grinding and hydrothermal synthesis strategy is adopted.Through the material morphology to improve the metal oxide semiconductor sensing performance,reduce the detection temperature,and explore its NO sensing mechanism.Based on this,relevant research is carried out.The specific research contents are as follows:?1?coral-like zinc oxide?ZnO?material was prepared by solid phase heating method without solvent in green,and the gas sensor for detecting NO at room temperature?21±2??was realized.In the experiment,zinc acetate was used as the zinc source and oxalic acid was used as the carbon source to prepare zinc oxide,which showed a higher selective response to NO at room temperature.Studies have shown that the ratio of zinc acetate and oxalic acid has an important effect on the sensitivity of gas sensors made from zinc oxide:When the ratio of zinc acetate to oxalic acid in the reaction system was 1:1,coral-like particles with 15-45 nm nanoparticles are obtained.Smaller particle size can provide more gas adsorption sites and improve the sensitivity of gas sensor.As the precursor produces zinc oxalate during grinding,and zinc oxalate releases CO₂ during the calcination process,the resulting ZnO powder has a porous structure,which is conducive to the rapid adsorption and desorption of gas.Moreover,the pores produced by the linear molecules of CO₂ are consistent with the structure of the NO molecule,which realizes the selective detection of NO.The detection concentration of zinc oxide?ZnO?sensor at room temperature is 5-100 ppm NO,the sensitivity to 40 ppm NO is as high as23.59,and the response and recovery time are 331 s and 1285 s respectively.?2?A one-step hydrothermal method is used to prepare a rod-shaped indium oxide?In₂O₃?for detecting NO gas,and a gas sensor for detecting NO at room temperature?21±2??.In the experiment,the change of urea content during the reaction process affects the sensitivity of the gas sensor.When the molar ratio of urea to indium nitrate was 10:1 and 0.0076 g sucrose,the nanorods with the diameter of 11.0±0.8 nm and many uniform sizes on the nanorod pores with a specific surface area of 12.36 m²/g were obtained.The results show that rod-shaped indium oxide has a high sensitivity to NO gas,the sensitivity to 1 ppm NO is 2.67,the minimum detection limit is 500 ppb.It has good repeatability and stability,the relative standard deviation of sensor stability within 3 days is 0.72%.