Operando Studies on gas sensors

In order to understand their interaction with the gases, two types of sensitive materials are investigated - semiconducting metal oxides (SMOX) and polymers. In both cases, all investigation techniques are used in sensor operation conditions (operando) meaning that the samples are fabricated in the same way in which the real sensors are (e.g. the SMOX are deposited as polycrystalline, thick, porous films onto substrates provided with electrodes and heaters) and are studied in real-life like conditions (heated between 200 and 400 °C for the SMOX, at normal pressure, in the presence of humidity and of the target gases).

Most of the operando experiments are performed in-house; for SMOX they include: DC resistance, AC impedance spectroscopy, work function changes (Kelvin probe), catalytic conversion, Hall Effect and Diffuse Reflectance Infrared Fourier Transformed Spectroscopy (DRIFTS) measurements. In cooperation with ETH Zuerich and Karlsruher Institut für Technologie (KIT), operando XAS studies are performed regularly at the European Synchrotron Radiation Facility (ESRF) at Grenoble.

More information about operando studies on SMOX: AG Weimar.

In the case of the polymers, the in-house operando techniques are: AC impedance spectroscopy, cyclic voltammetry, work function changes, mass changes by using quartz micro-balances (QMB) and transmission IR spectroscopy measurements.

More information about operando studies on Polymers: AG Weimar.