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Study on the Gas-sensing Properties and Sensing Mechanism of Nanosized In2O3

Author: ZhanZiLi
Tutor: JiangDengGao
School: Zhengzhou University
Course: Chemical processes
Keywords: In2O3 Microemulsion Nanomaterials Gas sensor Gas Sensing Properties Sensing mechanism
CLC: TB383
Type: PhD thesis
Year: 2003
Downloads: 580
Quote: 2
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Abstract


Semiconductor gas sensor because of its simple structure, low cost, high sensitivity, and mature technology, so that the combustible gas, toxic gas leak detection alarm, environmental gas monitoring and other fields has been widely used. SnO 2 , Fe 2 O 3 , ZnO traditional semiconductor material and technology workers has been carried out since the 1960s The extensive and in-depth research the SnO 2 -based gas sensor has been great development in the civil and industrial applications. But so far, the semiconductor gas sensor there are still poor selectivity, high power consumption, environmental temperature and humidity effects, and their understanding of the sensing mechanism is not very clear, thus limiting the development and application of gas sensor. Semiconductor gas sensor, the new gas sensing Nano In 2 O 3 synthesis gas sensing performance and sensing mechanism related issues were more systematic study. Reads as follows: In this paper, laser transmission method to study the phase behavior of the non-ionic surfactant Triton X-100 microemulsion system, the effects of the oil phase (hydrocarbons), the cosurfactant temperature and salinity on W / O (oil-in-water type) microemulsion regional impact of screening a microemulsion system for the synthesis of inorganic nanomaterials. The system has a large W / O microemulsion region, and large amounts of water solubilized by the impact of salinity and pH, and is the ideal synthesis of inorganic nanomaterials microemulsion system. A microemulsion synthesis of nano In 2 O 3 process route, research the influence In 2 O < / sub> particle size of a variety of factors, to optimize the synthesis conditions. Under optimized conditions prepared In 2 O 3 , is spherical, particle size distribution within a very narrow range. Particle size, the average particle diameter of the smallest particles can be controlled under a certain degree of 6.44nm, the maximum diameter of 42.00nm. Nano In 2 O 3 gas sensing performance study results show that In to 2 O 3 on the H 2 , iC 4 H 10 and C of 2 H 5 OH has a more high sensitivity, and low resistivity, and high catalytic activity, an ideal material for the study of a new low-power gas sensors. In this paper, In 2 O 3 smaller resistivity and high catalytic activity characteristics of new low-power gas sensor research. For the first time developed a new low-power hotline combustible gas gas sensor and hotline C 2 H 5 OH gas gas sensor. Both gas sensor are the traditional beside the thermal gas sensor compared to reduce power consumption by more than half, with good resistance to environmental temperature and humidity interference ability to solve the next hot-gas sensors and long-term existence of these two problem, while the developed components also have high sensitivity, response - shorter recovery time, and good stability. Both gas sensor has been put into production in Henan Hanwei Electronics Co., and users praise the domestic market has not seen the sales of the hot gas sensor. Surface modification technology developed low power Hotline H 2 gas sensors and LPG (liquefied petroleum) gas Chinese Abstract sensitive components. H: gas sensor H: high sensitivity and good selectivity, elements of the environmental temperature and humidity effects, good stability. LPG gas sensor power consumption (75mw) is much lower than the next to the hot gas sensor (700 Troubles), the component in response to a short recovery time, better stability, and laid the foundation for development of portable gas detector. Hotline gas sensor in recent years began to research a new type of semiconductor gas sensor, there is no analysis of its sensing mechanism is reported. Its sensing mechanism of this article analysis, discusses the factors that affect the sensitivity of the gas-sensitive element, next to the basic sensing mechanism of the hot gas sensor with traditional thermal type the same as the gas-sensitive element, is also relying on the target gas and the surface of the gas-sensitive material the negative oxygen ions adsorbed on the reaction (0 and 02 first-class), consume some of the negative oxygen ions, causing the resistance value of the gas sensing material changes to achieve the purpose of detecting the target gas. Hot gas sensor sensing mechanism indirectly heated gas sensor is also different from the theoretical analysis of the factors that impact the Hotline-type gas sensor sensitivity, sensitivity formula is derived. I.e. the target gas and the gas-sensitive material adsorbed on the surface of the reaction of oxygen ions not only makes the resistance value of the sensitive element is reduced, and the compensation element of the resistance value increases, the sensitivity of these two aspects of the effect of the element has a contribution, whose common effect the results so that the wire-type gas sensing element has a high sensitivity, the same due to the presence of a compensating element, the environmental temperature and humidity is not only affect the resistance of the sensitive elements and also affects the resistance of the compensating element, and the impact on the sensitive element and the compensating element is the same trend. (simultaneously increases or decreases), the effect of the temperature and humidity of the sensitive element has been partially compensated, so the hot type gas sensing element bad environment temperature and humidity is less affected. The study found that the catalytic performance of its gas sensing performance of gas-sensitive materials are closely related to, directly affect components of the catalytic activity of the sensitivity of size. The catalytic activity is too high, then the outer layer of the target gas in the gas-sensitive material to be reacted away, can not affect the resistance value of the inner layer of the gas-sensitive material, the element sensitivity but low, and the catalytic activity is too low, then the target gas can not be adsorbed oxygen The ion-generating chemical reaction, also showed low sensitivity. Therefore, we think that the ideal situation is when the target gas diffusion into the gas-sensitive material innermost reacted, then the highest sensitivity of the device.

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