Development Of Acetylene Gas Sensor Based On The Nano-materials Of Titanium Dioxide

Acetylene gas widely exists in oil shale pyrolysis gas and transformer oil dissolved gas.It has become one of the current research priorities because of its extremely low explosion limit and wide explosion range.Acetylene gas sensor plays an important role in detecting acetylene gas released during the pyrolysis of oil shale and on-line monitoring dissolved gas of transformer oil.Semiconductor gas sensors are widely used in many gas sensors,but they also have some disadvantages of current semiconductor gas sensors,such as slow response-recovery time and poor stability.TiO₂ nanomaterials were prepared by sol-gel method with tetrabutyl titanate,ZnO/TiO₂nanomaterials were prepared by hydrothermal method.The structure and morphology of the nanoparticles were characterized by X-ray diffraction,scanning electron microscopy and BET,and two kinds of nanomaterials were made into a side-heating gas sensor.CGS-8 intelligent gas-sensitive analysis system was used to detect the gas performance of the gas sensor to acetylene.The comparison of the test results show that the response to acetylene reach up to 4.74at the concentration of 200 ppm for the TiO₂ nanomaterial sensor,its response time is 8 s while recovery time is 2 s.The response to acetylene can reach up to 9.9 at the concentration of 200ppm for the TiO₂ nanomaterial doped with 10%ZnO nanomaterial sensor,its response time is 5 s while recovery time is 2 s.The response time and stability of the gas sensor are improved obviously by doping ZnO.The main research works are as follows:?1?TiO₂ nanomaterials were prepared by sol-gel method,it were characterized by XRD,SEM and so on.The results show that the nanomaterials calcined are anatase and rutile mixed crystals at 600?,the particle boundary is clear,and there is basically no agglomeration phenomenon.The nanomaterials were made into a gas sensor and tested for its response to acetylene gas.The test result shows that when calcined at 600?,the gas sensor has a best gas sensitivity to acetylene when the working temperature is 280?.?2?Four groups of TiO₂ nanomaterials doped with different proportions?5%,8%,10%,12%?of ZnO were prepared by hydrothermal method and characterized by XRD,SEM and BET SEM images show that the surface of TiO₂ nanoparticles is smooth and uniform in size with slight agglomeration.There are voids between the particles,and the arrangement is loose,while the particle size is larger than TiO₂ nanoparticles.The nanomaterial was made into a gas sensor and tested for its sensitivity to acetylene gas.The test results show that the gas response of ZnO/TiO₂ gas sensor is better than TiO₂ gas sensor.The best doping ratio is n?ZnO?:n?TiO₂?=10% and the optimal working temperature is 280?,the response to 200 ppm acetylene gas can reach up to 9.9.The gas sensors were placed at the aging station for 0-30 days,then its stability was tested.The results show that the sensitivity of the sensor to acetylene gas changes gently with the increase of ZnO doping ratio which proved that the sensors have a good stability.?3?The gas sensing mechanism of TiO₂ nanomaterials and ZnO/TiO₂ nanomaterials were discussed.The gas-properties improving when TiO₂ nanomaterials are doped with ZnO nanoparticles,which improve the agglomeration phenomenon of TiO₂ nanomaterials,increase the specific surface,provide more electrons for the nanomaterials,and improve the speed of adsorption and desorption.