Preparation Of Oxide Sensitive Materials By Biotemplate And Their Gas-sensing Properties

Gas sensors are widely used in gas detection such as atmospheric pollution gases, poisonous and harmful gases, flammable and explosive gases. Among various kinds of gas detection method, the semiconductor oxide gas sensors have received much attention. Semiconductor oxide as the core part, its composition, morphology and grain size have a direct correlation on its gas sensitive performance. Porous hierarchical structures are ideal structures of gas sensitive materials. However, because of the limitation of synthesis process and technical, construction of porous hierarchical structure still have some problems, such as simple structure, single type, lack of consistency and order, etc. Biotemplate takes complex diverse species in nature as templates, using the induction or limiting of specific surface chemical functional groups to well copy the morphology and microstructure of original template in the process of synthesis, and achieving highly hierarchical porous, consistency and ordered structure of new material finally. In this paper, preparation of oxide sensitive materials by biotemplate and study their gas-sensing properties. Paper content as followed as below:Take cotton wool as template to prepare fibrous SnO2 materials, combining with three different preparation method of solvent thermal, ultrasonic and impregnation. Characterization of its morphology and structure and test its gas sensitive of SnO2 materials by above mentioned preparation method, test results show that the material prepared by impregnation method have a higher ethanol sensitivity. Based on above mentioned impregnation method and cotton wool template, different concentrations of CeO2 doping on SnO2 based materials are produced and TG/DSC, XRD, SEM, EDS, TEM, BET and FTIR are characterized. Gas sensing properties test shows that acetone sensitivity of material enhance by adding Ce element, and sensitive mechanism of composite materials are analyzed.Preparation of surface three-dimensional porous skeleton mesh SnO2 and Al doping materials by rape pollen biotemplate and characterization microstructure and composition of prepared materials. Ethanol sensitivity of prepared materials are test, the results show that ethanol sensitivity and selectivity of materials are improved and working temperature is reduced at the same time by doping of Al element.By using grapefruit exocarp as template to prepare lamellar and plicated membranes SnO2 materials and the morphology, microstructure and electronic state of as-prepared materials are characterized. Then mechanism of template synthesis is studied and formaldehyde gas sensing properties are tested. It can be seem from gas sensitive test results that as-prepared SnO2 gas sensor shows low detection temperature and high sensibility, selectivity and stability to formaldehyde gas, humidity has an effect on its sensitivity at the same time. Based on above mentioned grapefruit exocarp template, different concentrations of precious metal Pd doped SnO2 materials are fabricated and its microstructure and electronic state are characterized. Formaldehyde sensing properties of Pd doped SnO2 materials show Pd doped effectively reduce the working temperature. The sensitive mechanisms of Pd doped SnO2 materials is studied. Grapefruit exocarp is also used as template to build WO3 material. Exploration of the template synthesis mechanism and characterization of its microscopic characteristics. Gas sensitive properties of WO3 material are processed and results show that WO3 material have high toluene response value and good selectivity.Biotemplated SnO2 materials templated by cotton wool, rape pollen and grapefruit exocarp are contrastive analyzed according to characterization results of XRD, SEM, EDS, BET, average particle size, pore size distribution, porosity and so on. The templated synthesis processes of materials prepared by biotemplate have been preliminarily expounded. At the same time, the gas sensing properties of as-prepared biotemplated SnO2 materials, such as sensitive gas, response value, optimum working temperature, selectivity and long-term stability, are contrastive analyzed. Then a preliminary explanation about the gas-sensing differences of SnO2 materials templated cotton wool, rape pollen and grapefruit exocarp is given from respects of the surface structure, particle size, hole and specific surface area.