Comparative evaluation of the prospects of using sulfide-conducting solid electrolytes in the composition of sensors for hydrogen sulfide and sulfur dioxide

The article presents a comparative evaluation of the prospects for using sulfur-conducting solid electrolytes CaY2S4 and CaYb2S4 doped with ytterbium sesquisulfide (Yb2S2) as part of solid electrolyte sensors of sulfur-containing gases (hydrogen sulfide and sulfur dioxide). The relationship between the magnitude of the sensor signal and the electrode reactions at the working electrode is considered, taking into account the partial pressures over its components, and the nature of the signals during the detection of H2S and SO2 is substantiated. The intervals of gas concentrations that fall into the group of linear signs depending on the content of the detected gas are determined. It has been suggested that the reason for the low sensitivity of the sensors in the range of P-S < 10(-10) atm is a kinetic nature. As a result of the study, it was found that when detecting a gas containing hydrogen sulfide, the limiting stage is the reaction of adsorption of hydrogen sulfide on the surface of the working electrode (reaction of the first order), and when determining the content of sulfur dioxide, the limiting rate reaction is the desorption reaction of a by-product - oxygen (reaction of the second order). It was carried out a kinetic study of the relationship between the sensitivity of hydrogen sulfide and sulfur dioxide sensors and outlined the sensitivity path of performance sensors. It was found that for the detection of hydrogen sulfide and sulfur dioxide, it is more promising to use the sulfur-conducting solid electrolyte CaY2S4 - x mol.% Yb2S3, where x is 0 to 16 mol.%, the sensor sensitivity is an order of magnitude higher than the use of solid electrolyte CaYb2S4 - x mol.% Yb2S8, where x is 0 to 12 mol.%.