CO Gas Detection on Pt∣YSZ∣Pt Solid Electrolyte Sensors by Methods Based on Dynamic Voltage Variations

Title data

Ruchets, Anastasiya ; Donker, Nils ; Zosel, Jens ; Schönauer-Kamin, Daniela ; Moos, Ralf ; Guth, Ulrich ; Mertig, Michael:
CO Gas Detection on Pt∣YSZ∣Pt Solid Electrolyte Sensors by Methods Based on Dynamic Voltage Variations.
In: Journal of the Electrochemical Society. Vol. 168 (2021) Issue 11 . - No. 117506.
ISSN 1945-7111
DOI: https://doi.org/10.1149/1945-7111/ac2fc5

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Abstract in another language

CO detection with a dynamically operated solid-electrolyte sensor (SES) was investigated at 700 °C–750 °C in the concentration range between 0 and 150 vol.-ppm CO. Dynamic voltage variations by electrochemical impedance spectroscopy, cyclic voltammetry, and square-wave voltammetry showed a pronounced sensitivity to the presence of carbon monoxide in gas mixtures in the investigated concentration range at optimized experimental conditions. Specific differences of CO detection in reducing and oxidizing conditions are described in detail. Selectivity to oxygen, nitrogen monoxide, and hydrogen are discussed. Since the methods can also be used to selectively determine oxygen, nitrogen oxide and hydrogen, they open up new possibilities for complex multiple gas analysis.Solid electrolyte sensors (SESs) based on oxide ion conductors are already in use to monitor exhaust gas components, such as carbon monoxide, hydrocarbons, and nitrogen oxides. Their application range could be extended significantly if they become more selective to the different gaseous components. While potentiometric SESs with catalytically highly active electrodes establish the thermodynamic equilibrium, and therefore, allow to measure the equilibrium oxygen partial pressure p(O2)eq the selective detection of redox active gas components with such sensors requires kinetic discrimination at the electrode/electrolyte interfaces. One possibility to enable the selective detection of combustibles like CO, hydrocarbons, or H2 with SES is to establish a mixed potential at electrodes with tailored catalytic activity. Other approaches utilize constantly polarized electrodes 1,2 or sinusoidally polarized electrodes (AC impedance measurements) for CO detection with improved selectivity. 3 These sensing techniques were applied at gas-symmetric electrodes (working and reference electrode in the same atmosphere) as well as at electrodes in separated atmospheres (air reference electrode). 4 Since successful selectivity improvement could be demonstrated for other analytes like NOX with stepwise polarization voltage variation, 5 the question arose whether those techniques could be also applied for CO detection. This work was directed on the application of stepwise dynamic voltage variations such as cyclic voltammetry (CV) and square-wave voltammetry (SWV) on a tubular Pt∣YSZ∣Pt sensing system with air reference electrodes. Impedance spectroscopy (EIS) was conducted for comparison as well.