Selective determination of hydrogen by the metal oxide sensor
Abstract
Semiconductor sensors are commonly used to solve the important practical problem of determining the concentration of hydrogen in the air. Their disadvantage is the low selectivity, which can lead to a false alarm when the analytical device enters the atmosphere of other gases-reducing agents, for example, ethanol vapor, ammonia and so on. To increase the selectivity, the temperature modulation in combination with the selection of the gas-sensitive sensor layer was used. Due to the temperature modulation, the volume of information about each analyte was increased, because its features associated with the kinetics of sorption on the sensor surface, with the kinetics of the chemical interaction between the reducing analysts and chemisorbed oxygen, with the kinetics of the desorption of chemical interaction products were revealed. However, the information obtained in the experiment about the qualitative composition of the medium is contained in the obtained kinetic data in an implicit form, while the procedure for conducting a qualitative analysis using low-selective sensors has remained undeveloped to date. In this paper, a method of qualitative analysis was proposed, based on the determination of empirical coefficients in the equation relating the concentration of the analyte gas to the sensory response (electrical resistance) for different moments of time during the measurement cycle.
The use of temperature modulation in combination with the selection of the gas-sensitive layer composition allowed to increase the sensitivity of the quantitative analysis by one or two orders of magnitude (depending on the range of hydrogen concentrations).
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References
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