A highly selective CO sensor using LaMnO3 electrode-attached zirconia galvanic cell

Abstract For enhancing the selectivity of a CO sensor, which comprises a zirconia galvanic cell and functions in accordance with a mixed electrode potential, perovskite-type oxides, LaMO3 (M = Mn, Cr, Fe and Co), have been found to be promising electrode materials. All these materials give higher sensitivity to CO than to H2. The sensor attached with LaMnO3 electrodes exhibits a quick response (i.e., less than 10 s to reach 90% of the steady-state e.m.f. value) at 400°C. Its e.m.f. to 2000 ppm CO is 6–18 times higher than that to the same concentration of H2, CH4 or C3H8. Such high selectivity to CO seems to reflect that the catalytic activity of LaMnO3 is higher for the oxidation of CO than for that of H2, CH4 or C3H8.

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