Use of cyclovoltammetry for selective solid electrolyte sensors

Titelangaben

Ruchets, Anastasiya ; Donker, Nils ; Schönauer-Kamin, Daniela ; Moos, Ralf ; Zosel, Jens ; Guthe, Ulrich ; Mertig, Michael:
Use of cyclovoltammetry for selective solid electrolyte sensors.
2019
Veranstaltung: 2nd Cross-Border Seminar on Electroanalytical Chemistry (CBSEC) , 10.4.-12.4.2019 , Budweis.
(Veranstaltungsbeitrag: Kongress/Konferenz/Symposium/Tagung , Vortrag )

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Abstract

Up to now, solid electrolyte sensors (SES) have mainly been operated with stationary methods such as potentiometry, amperometry or coulometry. These methods are not suitable for selective determining of several redox-active components in gas mixture. In contrast,dynamic methods such as pulse polarization, CV or impedance spectroscopy can use different kinetics of the electrode reactions and allow to detect individual components independently. This is demonstrated here with a commercial SES based on yttria-stabilized zirconia, which was tested with cyclovoltammetry (CV) in gas mixtures containing redoxactive gases such as H2, O2 and water vapor.Cyclic voltammograms were recorded at an SES with a potentiostat at different scan rates (10-1000 mV/s), ranges (-0.7 and -0.1 V vs. air reference), sensor temperatures (650-750 °C), gas flow rates (10-50 sccm) and gas concentrations of the components mentioned above in N2(0-200 vol.-ppm). The results show that both H2 and O2 can be measured quantitatively and with high selectivity at different H2O concentrations. Hydrogen related oxidation peaks are found at low scan rates of 20 mV/s, while oxygen reduction peaks arise at high scan rates above 200 mV/s. Furthermore, H2 related peaks are found at 700 °C at 10 ml/min and at 750 °C at all investigated flow rates, while oxygen peaks were measured in the complete temperature range. This enables selective determination of H2 and O2 in non-equilibrated mixtures. The peaks found for these components obey the Randles-Ševčik equation in distinguished concentration ranges.