A Study On Microwave Controllable Synthesis Of Zinc Oxide And Its Gas Sensing Properties

Zinc oxide is a kind of gas sensing material with wide applications and excellent performance,whose sensing property is closely related to its morphology and structure.Exploring the controllable synthesis of zinc oxide and the relationship between micro-morphology and gas sensing properties is very important to promote the manufacturing of gas detectors with superior performance.In this thesis,a series of zinc oxide particles with controlled morphologies were made through two kinds of microwave synthesis methods.Then,the effects of synthesis conditions to the microstructure of zinc oxide were studied.Finally,gas sensing properties of the zinc oxide were measured and evaluated.Microwave hydrothermal method was used to synthesize sphere-like,rodlike and plate-like zinc oxide particles,of which the structures and morphologies can be precisely controlled by adjusting the composition in the mixed solvent.The zinc oxide precursors with different morphologies were prepared by microwave-assisted synthesis under atmospheric pressure,by controlling the dosage of urea in zinc nitrate solution.The flower-like zinc oxide with micro-nano hierarchical structures was obtained by simple calcination of zinc oxide precursors.By comparing the gas sensing performance of zinc oxide with different morphologies,several gas sensors with excellent ethanol detection properties,whose sensitivity can reach to 250 and response time is about 10 s,have been successfully constructed and their response mechanisms have been explained.This work is innovative in the following points that the adjustment of the morphology of zinc oxide can be realized by adjusting the composition in the mixed solvent or the concentration of the precipitant in the progress of microwave synthesis.Furthermore,by improving the ceramic tube brushing process,consistency of the gas sensors is increased.Based on the predecessors' work,the data of gas sensing test is deeply excavated,and the gas sensing performance of the sensors is analyzed by using the graph of the response curves in the phase space.