Metal Oxide Structure Regulation And Its Gas Sensing Enhancement Strateg

Real-time monitoring of toxic and harmful gases by gas sensors is a permanent requirement in many fields.The gas sensor based on metal oxide semiconductor（MOS）has the advantages of simple structure,low cost,easy manufacture,high sensitivity and rapid response,and have become the core of gas sensors.The innovation of nanotechnology leads to the creation of MOS sensing materials with more diversity,which is conducive to the application of sensors to more complex working environments.In this thesis,the structure and component of MOS are regulated aiming at improving the sensor functions.The relationship between the materials structure and the gas sensing performance was studied,which provided new ideas for the development of gas sensors.（1）WO₃ thin film was prepared by thermal evaporation method.The effect of temperature on the surface morphology and structure of WO₃ thin film was studied.The films annealed at500 ℃ have the best performance to triethylamine（TEA）,including very high response,good selectivity,fast response and low detection of limit.The excellent sensor performance was attributed to the enhanced adsorption of oxygen species due to the presence of abundant oxygen vacancies and the large specific surface area of the material surface.（2）Co₃O₄/AgO nanorod heterostructure was synthesized by wet chemical method,which was used as sensing materials for TEA detection at low temperature.The AgO loaded heterostructure showed enhanced gas sensing performance,which was 2-3 times higher than that Co₃O₄ sensor.The reduced optimal operating temperature expands the application of Co₃O₄ sensor at low temperature.In addition,it also showed low limit of detection and excellent reproducibility.The enhanced performance was attributed to the catalysis and electronic sensitization of AgO nanoparticles.（3）A large 2D layered Ni/In MOF precursor was prepared by ultrasonic synthesis.In₂O₃modified NiO nanoparticles were obtained by high temperature annealing,and the NiO/In₂O₃heterostructure was applied to NO₂ detection.Besides,the effect of In₂O₃ content on gas sensing performance was studied.It is found that In₂O₃ modification enhances the gas sensing performance of NiO nanoparticles.The sensor has excellent selectivity for NO₂ gas at low temperature and good detection ability for low concentration NO₂.