Study On The Preparation And Gas Sensing Properties Of Volatile Organic Compounds (VOCs) Sensors

In recent years, the demand of sensors for safety control and environmental monitoring has been expanded enormously. Especially, more and more people pay much attention on the detection of volatile organic compounds (VOCs) such as formaldehyde, pyridine, trichloroethylene, benzene, toluene, ethylene, etc.. The volatile organic compounds (VOCs) are much harmful to living things. For example, the aromatic hydrocarbons such as benzene, has been found to be responsible for the leucocythemia and lung cancer. And they are frequently encountered in every day life. For example, they exis in unleaded gasoline, paint, etc. So, it is necessary to develop a cheap and portable technique to detect or measure these kinds of substances, in the air.In this thesis, the VOCs gas sensing materials are prepared by solid state reaction method and sol-gel method respectively using TiO₂, Al₂O₃, SnO₂,In₂O₃ and Cr₂O₃ powders as raw materials. The ceramics gas sensors are made from above sensing materials prepared by means of traditional ceramics gas sensor processing. And the gas properties of these sensors are measured. The optimal composition of the sensing materials and the optimal sensor processing are obstained.The results demonstrated that the ceramic sensors made from TiO₂ mixed SnO₂, In₂O₃ or Cr₂O₃ powders respectively are all sensitive to benzene, and the sensors made from TiO₂ mixed with SnO₂ powders have the best sensitivity to benzene. The ceramic sensors made from TiO₂ mixed with In₂O₃, or Cr₂O₃ powders respectively show good response to acetone. The ceramic sensors made from TiO₂ mixed SnO₂ or Cr₂O₃ sensors show good sensitivity to formaldehyde and the Cr₂O₃ -mixed sensors...