Study On Gas Detection Characteristics Of Tin Oxide Doped With Oxides Gas Sensor

Dissolved gases analysis is one of the important methods to process the powertransformer status maintenance, Hydrogen (H2) and carbon monoxide (CO) gases aremain characteristic gases in transformer oil, which can reflect the electric fault oroil-paper insulation problem effectively. Gas sensor detection technique is the key totrace amounts of gases analysis. Semiconductor gas sensor has been wildly used for itslow cost, high sensitivity, easy maintain and many other advantages. To solve problemsof semiconductor gas sensor, such as the bad stability and selectivity, short working lifeand so on, some new gas sensing technologies have been used to on line monitor thegases dissolved in transformer oil, which can satisfy the need of actual engeeringapplication.To study the gas sensor and its gas detection properties deeply is of greatsignificance for promoting the gas detection technology of the sensor. For the detectionproperties of tin oxide doped with copper oxide (CuO) and zinc oxide (ZnO)nanoparticles gas sensors to H2and CO, this paper introduced the fabrication method ofgas sensors and experiments procedure. X-ray Diffraction (XRD)、Field EmissionScanning Electron Microscopy (FESEM)、Transmission Electron Microscope (TEM)、and High Resolution Transmission Electron Microscopy (HRTEM) were used toanalyse the microstructure of CuO-SnO2、ZnO-SnO2and SnO2nanoparticles, then thegas sensing mechanism was analysed. The results show that:①One can draw conclusions through the analysis of morphology characterizationas follows:CuO-SnO2gas sensor shows higher gas sensing property because of theinfluence of heterojunction and absorbed oxygen, as well as the conversation betweenp-n junction and schottky barrier; while the better gas sensing characteristic ofZnO-SnO2nanomaterial is attributed to the formation of ZnO-SnO2heterojunction andthe smaller grain diameter; heterojuction would promote transfer of electrons andenhance the sensing property; however, smaller grain diameter will result in biggersurface area, which offer more reacton area for detected gases and absorbed oxygen.②Compared with SnO2gas sensor, the CuO-SnO2and ZnO-SnO2gas sensorshave higher sensitivity and resolution, and they show good linearity, stability andresponse-recovery characteristic, as well as lower optimum operation temperature to H2and CO. The sensitivity of gas sensor increases with the incease of operation temperature. However, if the operation temperature is too high, which is higher than theoptimum operation temperature, the high temperature can result in the desorption rate ofchemical absorbed oxygen higher than the adsorption rate, at last, the sensitivity willdecrease. At the same time, CuO-SnO2and ZnO-SnO2gas sensors both have a goodselectivity to H2and CO, and this can distinguish H2and CO from CH4、C2H6、C2H4andC2H2easily.③The CuO-SnO2and ZnO-SnO2nanoparticles gas sensors studied in this papereffectively improve the sensing properties to H2and CO gases dissolved in transformeroil, which provides a new idea for studing composite tin oxide gas sensor.