Development of a porous layer catalytically activated for improving gas sensors performances

A screen-printed thick film was developed to be overlapped to a gas sensing device for preserving it from contamination and degradation occurring in hostile environments, and also for improving its selectivity to a single pollutant gas when exposed to a complex atmosphere. This protective layer incorporated Al2O3 doped with Cs or Ba oxides as a catalyst material for eliminating gaseous interfering species, precisely CO2, to improve sensor response to CO. The best performances were obtained by depositing two, successive layers: the lower one, made of an alumina sol with a dispersed commercial α-alumina powder, just plays the role of protecting the sensitive material and electrodes from degradation, while the upper layer was obtained by the deposition of a screen-printable ink made of doped-alumina powders and is able to selectively adsorb CO2, just allowing CO to interact at the sensing material surface.