Electrocatalytic effects in gas sensors based on low-temperature superprotonics

The behavior of low-temperature hydrogen sensors based on the PbO2/heteropoly compound/Pt electrochemical cells, where heteropoly compound is H4SiW12O40·nH2O or MexH3−xPW12O40·nH2O (Me = Li, Na, K, Rb, NH4, x = 0, 2, 3), in H2–Ar and H2–air atmospheres was studied. All heteropoly compounds studied were shown to be electrocatalytically active in reactions involving hydrogen. The dependences of the emf of the sensors with different electrolytes on the hydrogen concentration (calculated relatively to the standard hydrogen potential in inert media or to the air potential in oxygen-containing media) are identical for all the electrolytes used. The rate of emf relaxation of the sensors upon the impulse admission of hydrogen depends, on the contrary, on both the anion nature (increases in the series from compounds of 12-silicotungstic acid to 12-phosphotungstic acid compounds) and the cation nature, increasing with an increase in the cation size in the series of alkaline metal cations. on our studies, we proposed the electrochemical solid-state sensor, which can determine hydrogen concentrations from 10−2 to 5 vol.% in inert gases and air without maintaining constant temperature and hydrostatic regimes in the temperature interval from −60 to +60 °C.