Semiconductor metal oxide sensor for hydrogen sulphide operating under non-stationary temperature conditions

The aim of the work was to create a selective gas sensor for hydrogen sulphide. As a result of adding ammonia to the zinc acetate solution, centrifuging the obtained zinc hydroxide and subsequent calcination, a polydisperse zinc oxide powder with a grain size of 5–50 nm was obtained. The material was characterized using X-ray phase analysis and transmission electron microscopy. Subsequently, silver nitrate and terpeniol were added to the zinc oxide nanopowder to form a paste. The gas-sensitive material was obtained by applying the resulting paste on a special dielectric substrate and subsequent calcination, as a result of which the terpeniol burned out, and the silver nitrate turned into an oxide (the mass fraction of the silver was 3%). A non-stationary temperature mode for the operation of the sensor was selected, in which, after rapidheating of the sensor to 450 °C (2 seconds), slow (13 seconds) cooling to 100 °C occurred. Each subsequent heating-cooling cycle with a total period of 15 seconds began immediately after the end of the previous cycle. The use of an unsteady temperature mode in combination with the selection of the composition of the gas-sensitive layer made it possible to obtain a response of 200 for a hydrogen sulphide concentration of 1 ppm. Along with an increase in sensitivity, a significant increase in selectivity was also observed. The cross-sensitivity for the determination of hydrogen sulphide and other reducing gases (CO, NH3, H2) was more than three orders of magnitude. Thus, this sensor can be used to detect hydrogen sulphide even in the presence of interfering components. The use of highly selective sensors in the tasks of qualitative andquantitative analysis can significantly simplify the calibration in comparison with “electronic nose” devices. Devices based on highly selective sensors do not require the use of mathematical methods for processing multidimensional data arrays.