Study On Sno₂-Base Traditional Gas-Sensing Material Modification And Gas Sensitive Properties To CO₂

SnO₂ gas sensors are widely used for detecting flammable gas and reductive gas , but little used for detecting CO2 for its inertia. CO₂ need be detected in some areas, such as environment protect, agriculture. Until now, several types of CO₂ sensors, such as capacitive-type, electrochemistry-type, resonance-type and solid electrolyte-type etc, are poor in sensitivity and their devices are complicated, expensive and large energy consume. So doped and coated SnO2 gas sensors for detecting CO₂ must be made by employing nanometer and semiconductorization techniques.In my paper, nano-size SnO2 were prepared by the Sol-gel method. Then the characteristic of the powders were investigated by DSC-TG, XRD, TEM and BET. Thick film elements were made and their surfaces were coated. Sensitivity, selectivity and reliability to CO₂ were detected. Last sensing mechanism of CuO-SnO₂ gas sensors for detecting CO₂ was studied.The prepared nano-size powders had large specific surface area and high surface activation. The grain and specific surface area of powders as annealed at different temperature were different, considered that 600 was rational annealed temperature. SnO₂ gas sensors doped 4mol% CuO had high sensitivity and selectivity for detecting CO2 SnO2 gas sensors coated La2O3 were sensitive for detecting CO₂, but were poor in selectivity. Environmental experimentation of gas sensors indicated that CuO-SnO₂ gas sensors were well in resisting high temperature, low temperature and humidity, SnO₂ gas sensors coated La2O3 were well in resisting high temperature and low temperature, but were poor in resisting humidity. Finally some questions of study were put forward and looked forward to the development of the gas sensor.