Research On Gas Sensor Based On Metal Oxide Composite Material

With the rapid development of science and technology and economy in the world,the process of industrialization is speeding up,petrochemical industry,energy exploitation technology and automobile industry are booming,and people’s living standard is moving towards high technology and intelligence.However,while high-tech and economic development bring convenience and intelligent life,it also causes the continuous deterioration of ecological environment and large-scale air pollution.These problems increasingly threaten the survival and development of mankind.Ammonia is a colorless and has a strong pungent odor gas,harmful to the human body,more than a certain concentration can be fatal.Above the explosive concentration,an explosion occurs.The main sources are experimental and industrial production.In daily life,ammonia gas is mostly produced during construction.Precursor chemicals have the property that they can be used as raw materials or auxiliary materials to make drugs.Methyl ethyl ketone,is a synthesis of easy to make poison raw materials.How to detect and monitor trace or even trace gases in real time is a difficult problem for researchers.Gas sensors are components that output electrical signals corresponding to the changes in the type and concentration of gases.They are mainly made of special materials and detection elements that are particularly sensitive to certain gases.Used to detect some VOCs(volatile organic compound)gases.Metal oxide semiconductor gas sensors can detect toxic and harmful gases.It has the advantages of quick response,simple structure,high sensitivity,low cost and easy to use.Semiconductor gas sensors based on metal oxides are important and are widely used in systems and safety monitoring,environmental protection,disease diagnosis,and process control.Using semiconductor gas sensors based on metal oxides to detect pollutants,toxic and flammable gases for environmental monitoring is a cost-effective and reliable method.Among many metal oxides,molybdenum trioxide nanorods are selected in this paper.The gas sensitive performance of the sensor is improved by using precious metal doping.Based on molybdenum trioxide nanorods,the nanoparticle modified nanorods were synthesized with SnO2 nanorods.It further improves the selectivity of the sensor and reduces the working temperature of the sensor.Based on TiO2,the nanoparticle modified nanorods were formed by combining with SnO2 nanocrystals,showing good selectivity.In this paper,SEM,EDS and XRD are used to analyze the morphology,microstructure and gas sensitive properties of the materials in detail.The main research contents are as follows:(1)In this paper,MoO3 nanorods were synthesized by hydrothermal method and further modified by precious metals to form Au@MoO3.Gas tests were conducted on pure MoO3 and Au@MoO3 sensors respectively,and both sensors showed excellent gas sensitive characteristics to ammonia gas.Au@MoO3 has a significantly higher response to 100 PPM ammonia gas than pure MoO3,and has strong anti-interference ability to other gases.(2)In this paper,the SnO2/TiO2 composite was prepared by hydrothermal method.Its microstructure was nanorods modified by many nanoparticles.Gas-sensitive tests were performed on the SnO2/TiO2 composite sensor,which showed excellent gas-sensitive characteristics to ammonia gas.Moreover,the combination of MoO3 and SnO2 reduced the optimal working temperature of the sensor.The response of SnO2/TiO2 nanomaterials to 100 ppm ammonia gas is significantly higher than that of pure MoO3,and the anti-interference ability of SnO2/TiO2 nanomaterials to other gases is relatively strong.(3)In this paper,SnO2/TiO2 material was synthesized by hydrothermal method,and its micro structure was composed of nanorods modified by nanometer points.In the methyl ethyl ketone gas test experiment,the prepared materials showed excellent sensitivity,good selectivity,short response time and recovery time and long-term stability of the response to methyl ethyl ketone in the gas sensitivity test results.The lower detection limit can reach ppb level.The SnO2/TiO2 composite material has great application prospect on methyl ethyl ketone sensor.