Abstract
Abstract. A new setup for characterization of solid material oxygen exchange and conductivity in a broad oxygen partial pressure range and at elevated temperatures is presented. The development target of this setup is directed towards the detection of ultra-low amounts of exchanged oxygen. For this, electrochemical cells made of yttria-stabilized zirconia (YSZ) were optimized and applied in a flow-through arrangement. The design and process measures enable a lower limit of detection below 100 pmol of exchanged oxygen. Furthermore, the system characteristics concerning oxygen dispersion, titration efficiency and electrode kinetics are described.
Highlights
Oxygen solid electrolyte coulometry (OSEC) performed with electrochemical cells made of yttria-stabilized zirconia is a long-standing method used for gas sensing, material characterization as well as biological or medical measurements of oxygen exchange (Fouletier et al, 1975; Teske et al, 1986; Uhlmann et al, 1999; Sahibzada et al, 2000; Vashook et al, 2012; Stöber et al, 2018)
Applications in liquid coulometry show that this method can provide significantly lower limits of detection (LOD) down to the pmol range or ppb concentrations, respectively
The corresponding ratios of 98.1 % and 99.6 % of recovered oxygen in cell two prove the outstanding precision of the setup for oxygen exchange measurements
Summary
Oxygen solid electrolyte coulometry (OSEC) performed with electrochemical cells made of yttria-stabilized zirconia is a long-standing method used for gas sensing, material characterization as well as biological or medical measurements of oxygen exchange (Fouletier et al, 1975; Teske et al, 1986; Uhlmann et al, 1999; Sahibzada et al, 2000; Vashook et al, 2012; Stöber et al, 2018). The method is based on the measurement of charges or currents for batchlike or flow-through titration of oxygen by solid electrolyte cells based on Faraday’s law. If the coulometric devices are equipped with measuring electrodes which support oxidation reactions in the gas phase by their high catalytic activity, the method can be applied for Faradaic titration of oxidizable gases like hydrogen, carbon monoxide or hydrocarbons (Schelter et al, 2014). In this case, the oxygen gas concentration has to be constant at a much lower value than the combustible concentration to be measured. New design and process optimizations were taken into account
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