Preparation Of Mesoporous Zno Material And Study On Its Gas Sensing Properties

The thin film gas sensor made of ZnO has advantages of fast response, short recovery time, good selectivity and pollution to environment and so on. ZnO, which is in the field of extensive application of gas-sensitive material. Nano ZnO film of high quality attracts more and more attention in recent years. ZnO thin film surface pore structure makes great effects on its performance.In this paper, nano ZnO thin film is prepared by sol-gel method. Highly-ordered nanocrystaline ZnO porous films are synthesized using zinc acetate Zn(CH3COO)2·2H2O as precursor and organic surfactant (polyethylene glycol (PEG)) as templates . The influence of experimental parameters on the microstructure, surface topography and gas sensitivity of ZnO films is studied.The following is some results:1. The hydrolyzing effect of Zn(CH3COO)2·2H2O is obviously reduced after complex agent's addition . Moreover, a better porous structure is obtained using diethanolamine (DEA) as complex agent .The influence of calcination time is greater than the influence of calcination temperature. The ZnO grain size with increase water temperature rising is not obvious.2. The pore size of the ZnO film with pore structure is more large as Zn(CH₃COO)₂ concentration is increasing. The pore density increases and decreases. The pore size of low molecular weight film is small and the pore density is higher. The pore diameter is large with the addition of PEG. When the temperature is 500℃, the surface of ZnO film is poor porosity holes and the pore density is higher . When the temperature is 70℃, it is favorable to form pore structure.3. Using static prepared gas, we have detected sensor's sensing character with an optimum heating voltage, and the sensitivity to ethanol is higher than to acetone. The best sintering temperature is 500℃. And the best concentration of Zn(CH₃COO)₂ is 0.6 mol/L . With the addition of PEG, the sensitivity of the gas sensor rises first and then reduces. The best optimal dosage is 0.7 g. The Sensitivity of both ethanoc and acetone is rising with the increase of its concentration.