Synthesis, Modification And Gas-sensing Of Nano-ZnO

Nanomaterials are applied widely in the fields of solar cells, nanogenerator, drug carrier, sensors and catalysis due to their unique properties. Recently, the research on gas-sensing of nanometer semiconductor has attracted people’s attention. At present, the report of materials related to gas-sensing focus on investigation of the gas response of ethanol, carbon monoxide, hydrogen and methane gas. However, less research on the gas-sensing of volatile organic compounds under low temperature and low concentration (e.g., amine, aldehyde, etc.) is found. Therefore, it is very important for human health and environmental protection to synthesize the efficient gas-sensing materials for detecting harmful volatile substances with low-concentration.For the existing problems of low selectivity and stability in detecting harmful substances, nanometer zinc oxide was synthesized and modified based on the design of experiment routes, and the gas responses to aldehyde and amine were investigated. The effects of structure, morphology of zinc oxide and metal modification on the gas-sensing also studied. The main research contents and conclusions are as follows:(1) Nanosized zinc oxide with pencil-like morphology was prepared and the gas-sensing properties were studied. The effects of time, temperature, ratio of reactants on the structure and gas-sensing properties were explored and the growth mechanism of pencil-like nano-ZnO was proposed. The results show that the pencil-like nano-ZnO with larger length-diameter ratio shows good gas sensing to dimethylamine in low concentration condition.(2) Nano-ZnO was synthesized and in-situ modified with copper, manganese and cobalt. The influence of metal types and the doping amount on the structure and the sensitivity was studied and the mechanism was described. The results show that there is obvious influence of manganese on the size and morphology of nano-ZnO. By optimizing the doping amount, the gas sensitivity to dimethylamine can be improved.(3) The net-like nano-ZnO was successfully synthesized by hydrothermal method, and the influence of the hydrothermal time, calcination temperature and the ratio of reactants on the morphology and sensitivity of the nano-ZnO were studied. The results show that, the right hydrothermal time is beneficial to the formation of the ZnO net structure, the higher the calcination temperature is beneficial to crystallization, reactant ratio of product influences gas sensitive.(4) Nano-ZnO was synthesized and in-situ modified with lanthanum, tin and cobalt. The influence of metals and the doping amount on morphology and the sensitivity were studied. The results show that, the doped lanthanum can improve the selectivity to acetaldehyde, the doped tin can improve the selectivity to Ethanolamine, the introduction of cobalt can improve the selectivity to triethylamine.