Highly selective solid electrolyte sensor for the analysis of gaseous mixtures

The operation principle of a commercially available solid electrolyte sensor was modified with respect to applications in flowing gaseous mixtures containing H2 and O2. For this purpose the generally applied coulometric or potentiometric operation mode was replaced by cyclic voltammetry. By varying the sensor temperature, electrode area and potential scan rate, the conditions for the characteristic peak formation for every gas component were determined. While hydrogen oxidation peaks arise at potential scan rates up to 100 mV s−1, oxygen reduction peaks develop between 200 and 1000 mV s−1. A linear relationship between peak area/peak height and concentration was found at concentrations ϕ (H2) < 100 vol. ppm and ϕ (O2) ≤ 500 vol. ppm. It could be demonstrated that hydrogen can be measured selectively at catalytically highly active Pt electrodes even in gas mixtures with comparably high oxygen concentrations by using cyclic voltammetry.