Dissertation > Mathematical sciences and chemical > Chemistry > Inorganic Chemistry > Chemical elements and inorganic compounds > Inorganic synthetic chemistry

Study on the Preparetion and Performance of ZnSnO3and CuPc/ZnO Gas Sensitive Materials

Author WenYun
Tutor LouXiangDong
School Henan Normal
Course Applied Chemistry
Keywords Dissolution-Pyrolysis Method ZnSnO3 surfactant CuPc/ZnO gas sensitiveproperties
CLC O611.4
Type Master's thesis
Year 2012
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“The Internet of Things” is known as another wave of global information industry after computer,internet and mobile communication. The sensors, as one of the important part of the perception layer, arethe base unit and the direct means to get the required information of IOT. The gas sensors are one kind of itand widely used in the design of bionic system such as electronic tongue, electronic nose etc. The gassensors have the important practical significance in the use of environmental monitoring and protection.ZnSnO3is a composite oxide semiconductor gas sensitive material, and it has good gas sensitiveproperties to reducing gas such as CH3CH2OH, H2S etc. First in this experiment, the SnO2precursor wasprepared by dissolution-pyrolysis method. Then the SnO2precursor and Zinc salt were reacted and calcinedto obtain the products in different conditions. Through the gas sensitive test, the kind of surfactant, theconcentration of surfactant, the temperature of calcining, the kind of dopant and the doping ratio wereconfirmed. On the other hand, the organic/inorganic hybrid materials are new type multifunctionalmaterials too, and this article preliminary discussed the preparation and gas sensitive properties of theCuPc/ZnO hybrid materials.(1) The SnO2precursor was obtained using citric acid and tin grain as raw materials bydissolution-pyrolysis method. The SnO2precursor and Zn(CH3COO)2·2H2O were mixed and reacted underthe assisted of the surfactant PVP, CTAB, PEG600, PEG1000and PEG2000, respectively. The compositeoxides precursors were obtained after drying and burning the as-obtained solutions. At last we got theproducts by calcining the composite oxides precursors at600℃. The XRD tests show that the products areZnSnO3powders, and the SEM images show that the products are loose spongy structure. Among theseproducts the product assisted by CTAB is the best loose.The gas sensitive tests of all calcined samples indicate that the ZnSnO3powder assisted with CTABhas the optimal effect. First, the optimal working temperature to detect H2S gas is255℃, lower than290℃,the temperature of the product without surfactant assisting; Second, the sensivity to100ppm H2S gas isenhanced to369.6, while the increased range to CH3CH2OH gas is smaller. So the selectivity is strengthenvery much, as to34.2of the selectivity factorKH2S/CH3C H2OH. In the meanwhile, The product with CTABhas a good sensitivity and selectivity to5ppm H2S.(2) Using CTAB as the selected surfactant, the influence to the gas sensitivity of the products ofCTAB’s concentration and the calcining temperature of composite oxides precursors was studied. TheCTAB’s concentration was0.2M,0.4M and0.6M, respectively. And the calcining temperatures ofprecursors were400℃,500℃,600℃,700℃and800℃, respectively. The XRD tests show that the mainlycomposed of calcining products at500℃,600℃and700℃are ZnSnO3powers. The gas sensitive tests tothese three kinds of samples show that the product assisted with0.2M CTAB and calcined at600℃has the ptimal gas sensitivity. Among all these samples it have the highest sensitivity to100ppm H2S gas and theoptimal selectivity factorKH2S/CH3C H2OHbetween H2S and CH3CH2OH gas.(3)Use0.2M CTAB as surfactant and600℃as calcining temperature, using La(NO3)3·6H2O andCe(NO3)3·3H2O as dopant and1%,3%,5%,7%and9%(mol) of Zn as doping ratio, the ZnSnO3powderwas doped by rare earth elements. The gas sensitive tests of the products show that the optimal doping ratioof these two rare earth elements is3%(mol). Among these deped materials the3%doped products have theoptimal sensitivity to100ppm H2S gas, decrease the optimal working temperature more, from255℃to210℃, and maintain the good selectivity at the same time. In the same doping ratio3%, the sensitivity to100ppm H2S gas of the material doped by Ce is increased more than that doped by La. However, thematerials doped by La is better than those doped by Ce from aspects of the selectivity.(4)The CuPc and the chloroform solution of ZnO nanoparticles were synthesized respectively. Thenthe CuPc/ZnO hybrid materials with different w(ZnO) were obtained using solution method. The XRD testsshow that the characteristic peaks of ZnO are more and more obviously with the increasing of w(ZnO) inCuPc/ZnO hybrid materials. This indicates that ZnO would separate from the CuPc/ZnO hybrid materialsand exist alone when w(ZnO) is up to a certain limit.The gas sensitive tests to these CuPc/ZnO hybrid materials show that the material of w(ZnO) is10%has the highest sensitivity. It can detection the low concentration of Cl2, and has a good selectivity andresponse characteristic, but the recovery time is relatively long.

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