ZnO Gas Sensor And Their Gas Sensing Properties

Zinc oxide, as an exceptionally important versatile metal oxide, has been considered an ideal material for chemical sensors. Because the advantage of zinc oxide are the raw materials easy to get, simplified operational procedure, lower cost,less pollution to environment and so on. The main advantages of the ZnO gas sensor:1. High sensitivity and detect various gases. 2. Simplified operational procedure and lower cost. 3. Small volume and strong components interchangeability. 4. Fine stability and good compatibility. But the disadvantages of the ZnO gas sensor also are obvious: 1. Higher resistance. 2. High working temperature. 3. The risk of detecting gas on the high temperature. 4. Poor selectivity. So that to explore the high-performance ZnO gas sensor has important practical value and significance. By discussing the working mechanism of ZnO has the very high reference value to develop the response of ZnO gas sensor.The different morphology of ZnO was synthesized by template method and microwave hydrothermal method, respectively. And by in-situ doping to improve the gas sensing properties of ZnO hollow microspheres. In this paper, we prepared ZnO hollow microspheres by template of carbon microspheres. The as-prepared products were characterized by field emission scanning electron microscopy, X-ray powder diffraction. The gas sensing properties of as-prepared products were investigated. It was found that the products exhibited high sensitivity toward ethanol at optimum 200?,the sensor is response and recovery time to 100ppm ethanol was only 3s and 16s, respectively.Besides, we report a facile microwave-assisted approach to synthesis mushroom-like ZnO. The products were characterized by field emission scanning electron microscopy,X-ray powder diffraction and transmission electron microscopy.By changing the reaction time and reaction temperature, probes into the mushroom-like ZnO synthesis process,and its growth mechanism are studied. Its gas sensing properties were tested for response to NO2. It exhibited excellent selectivity and high sensitivity to NO2 at low optimum temperature.In the end, the ZnO hollow microspheres that synthesized by microwave hydrothermal in-situ doping with different amounts of Pd and Au to improve its gas sensitive properties. It were characterized by field emission scanning electron microscopy, X-ray powder diffraction and EDX. To compare with the pure ZnO, the products has higher response, less response and recovery time and more excellent selectivity to ethanol. Though the test results we discussed the gas-sensing properties of the inference with doping amount.