LaOCl has recently been proposed as an alternative material to perform a resistive solid state based CO2 gas sensor. After the main sensing characteristics of LaOCl material have been tested, the sensing mechanisms which describe the interaction with CO2 need to be sorted.
In this topic, TPD -thermal programmed desorption- measurements introduce meaningful information about available types of adsorption sites as well as the way in which key species are chemisorbed onto the material surface.
In this work we will present TPD experiments performed on two different LaOCl samples obtained through different synthesis routes.
From previous studies, the role of hydrated carbonate-like species is known to be a key point in the sensing mechanisms, thus, the desorption peaks of CO2 and water are specially examined.
TPD experiments show two differentiated CO2 peaks, on one hand a low temperature peak likely due to the physisorption and, on the other, a higher temperature peak associated with an analogous H2O one that confirms the presence of above-mentioned carbonate-like hydrated species.
Morphological and structural characterisation of samples has been performed using several techniques like XRD, TEM and XPS. These studies highlighted important morphological differences between samples. In fact we named the samples according to the shape of their particles: stick-shaped and quasi-spherical.
Results will be discussed and related with the morphology and structure of each sample and, finally, sensing mechanisms will be proposed.
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