METHOD OF PRODUCING SENSITIVE ELEMENTS BASED ON SILICON-CARBON COMPOSITES AND MAKING GAS SENSORS BASED THEREON

摘要

FIELD: chemistry.;SUBSTANCE: invention relates to production of porous silicon-carbon composites by pyrolysis of silicon-resorcinol-formaldehyde aerogels and can be used to create sensitive elements of measuring devices of gas sensors used in chemical industry, as well as for production of semiconductor gas sensors based on chemoresistive effect and intended for detection of nitrogen oxides and ammonia vapours in air based on said sensors. Method of producing sensitive element of gas sensor, which operates based on chemoresistive effect, consists in combined formation of organic and inorganic sol and placing contacts in sol, followed by gelation, followed by replacement of water in the pores of the water with an organic solvent in the temperature range of 20 to 70 °C, drying of obtained gel in supercritical carbon dioxide medium and pyrolysis of obtained silicon-resorcinol-formaldehyde airgel at temperature of 700 °C in an inert gas medium to obtain silicon-carbon composites. If necessary, the manufactured sensitive element can additionally undergo acid activation in a medium of hydrofluoric acid for 24 hours with further washing with distilled water until reaching neutral pH and atmospheric drying. Also disclosed is a gas sensor based on a sensitive element made according to the proposed method.;EFFECT: invention provides manufacturing of highly sensitive gas sensor, which enables to detect presence of ammonia in concentration of not less than 0_125 % by volume and nitrogen oxides in concentration of not less than 1 % by volume.;3 cl, 1 tbl, 3 dwg