| Smell is one of the most important features of materials. The demands for volatile dectetion promoted the rapid development of gas sensors. Gas sensors are widely used in many fileds, such as air contamination dectetion, food quality monitoring, public security check, and disease diagnosis. Metal oxide sensor is the most widely used gas sensors for its high sensitivity, low cost, convenient to use and easy to micromation. However, its biggest disadvantage is selectivity insufficient. Metal oxide array is a powerful approache to obtain good selectivity, but there are many work to do for optimizing a gas sensor array. For example, how to choose the best combination of materials and how to find out the suitable operation conditions(such as temperature) for a certain application.Surface modification is one of the ways to promote metal oxide gas sensing properties through material synthesis, which could not only change the surface depletion layer distribution but also adjust the surface chemical activity of metal oxide. What's more, there are many elements could be chose from for surface modification. So, surface modification is an easy, effective and flexible method to optimize the gas sensing properties of metal oxide materials. Furthermore, under differente operation conditions, such as light and temperature, metal oxide have differente gas sensing capabilities. For instance, metal oxide gas sensor has an optimum operating temperature, its selectivity could be improved by temperature programming, and its sensitivity under indoor temperature could be enhanced by optical excitation, and so on. Therefore, the performance of metal oxdie gas sensors based three materials were adjusted by surface modification with more than 30 elements in this work. Moreover, their gas sensing abilities for hazardous gas dectetion, cereal mildew dectetion and strange ordor dectetion of leather under differente operating conditions were tested through high-throught material screening experiments. Besids, selectivity analysis and array optimization were carried on. As the gas sensing properties of metal oxide depend on surface chemical reactivity, this paper attempted to establish an effective access for acquiring the chemical adsorption and desorption activation energies of chemisorption oxygen on the metal oxide surface. And the selectivity differences of the metal oxide gas sensing films were analyzed based on these chemical reaction parameters.Firstly, gas sensors based on Sn O2?WO3 and Zn O was surface modificated by 34 elements. Their responses under differente temperatures to 9 hazardous gases were tested on a self-manufactured high throughput screening platform. The effects of the basis material and doping elements to the sensing properties of the gas sensors were analyzed by clustering method. Besides, a metal oxide sening array was optimized for the detection of hazardous gases.Secondly, the response-feature patterns to cereal and leather volatile of gas sensors which were based Sn O2, Zn O and WO3 nanopaticles and surface modificated by 32 chemical elements were tested by a heaspace E-nose. The effects of the basis material and doping elements to the response-feature patterns of the analyte were analysied. Furthermore, two materials with talent gas sensing capacities were optimized for the detection of each species of samples.Finally, a theoretical model for calculating the oxygen adsorption and desorption activation energy of metal oxide was established in this paper. And, the oxygen adsorption and desorption activation energy of Sn O2, Zn O and WO3 based gas sensing films were tested through temperature programming techniques. The relationships between the elements for surface modification and the oxygen adsorption/desorption activation energy were discussed. Moreover, the selectivity differences of metal oxide gas sensing materials were talked about based on the chemical reaction pamameters. |
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