STUDY OF THE ACTIVITY OF THERMOCATALYTIC HYDROGEN SENSORS AT NEGATIVE AMBIENT TEMPERATURES

The response of thermocatalytic hydrogen sensors with platinum group catalysts (Pt+3Pd and Ir) to heating voltage (S-shaped patterns) was studied at ambient temperatures from 17 ºС to (–48) ºС. It has been shown that for sensors with a Pt+3Pd catalyst, a decrease in the ambient temperature leads to a shift in the onset of the reaction of catalytic hydrogen combustion from 0 mV to 442 mV. The threshold temperature at which the catalytic combustion of hydrogen begins is determined and lies in the range of 17–22 ºС. It is shown that for iridiumbased catalysts, the response of hydrogen sensors does not depend on the ambient temperature, and combustion starts at 1.5 V, which corresponds to a temperature from 222 ºС to 190 ºС when the ambient temperature changes from 17 ºС to (–48) ºС, respectively.