Response of Catalytic Hydrogen Sensors at Low and Negative Ambient Temperatures

The purpose of this letter is to prove that the reaction of hydrogen combustion in a catalytic sensor can occur at room temperature. This letter was designed to examine the response of catalytic hydrogen sensors to heating voltage (S-characteristics) as the ambient temperature is changed from 17 °С to -48 °С. A platinum group catalyst based on Pt and Pd composite with molar ratio Pt:Pd = 1:3 was used as a catalyst. It was shown that the sensor starts responding to hydrogen upon zero heating voltage at 17 °С. When the ambient temperature decreases, an initial section appears on the dependences of the sensor response to hydrogen. This section contains no response and expands rightwards to the area of higher heating voltages from 0 to 442 mV as the ambient temperature decreases from 17 °С to -48 °С. This research identified the threshold temperature at which catalytic hydrogen combustion starts in a sensor with a Pt+3Pd composite catalyst. This temperature was found to fall in the range of 17-22 °С.