APPLICATION OF KEGGIN TYPE PHOSPHOTUNGSTOVANADIC HETEROPOLY ACID AS SENSITIVE MATERIAL FOR CARBON MONOXIDE SENSOR

Abstract

The possibility of using Keggin-type wolframvanadium heteropoly acid with the formula H5[PW10V2O40] as a sensitive material for the development of thin-film resistometric sensors for carbon monoxide is considered. In order to test the applicability of the selected heteropoly acid to solve the problem, thin films were obtained from an aqueous solution of the above-mentioned heteropoly acid by irrigation. Heteropolyacid films were formed on a dielectric citall substrate with metal interpenetrating nickel electrodes. To determine the sensitivity of a film consisting of heteropolyacid to carbon monoxide gas, a change in the electrical resistance of the film was recorded depending on the concentration of carbon monoxide in the air. An approximate alarm threshold was determined when the concentration of carbon monoxide approaches the maximum permissible concentration of the working zone, which is 20 mg/m3, in order to assess the possibility of developing signaling devices based on resistometric sensors, where the selected heteropoly acid can be used as a sensitive reagent. The conditions of interaction of carbon monoxide with the selected heteropoly acid are determined. These conditions consist in activation of a sensitive film consisting of heteropoly acid by ultraviolet radiation in the wavelength range from 230 to 290 nm. The proposed mechanism of interaction of heteropolyacid with carbon monoxide is considered and an explanation of the change in the number of charge carriers in a film consisting of heteropolyacid is proposed. The principal possibility of using a Keggin-type heteropoly acid with the formula H5[PW10V2O40] as a sensitive material for creating resistometric sensors for carbon monoxide without using catalytically active elements based on platinum, palladium or rare scattered elements is proved.