Kinetic analysis of low concentration CO detection by Au-loaded cerium oxide sensors

Abstract

Owing to its high toxicity, even at very low concentration, early detection of carbon monoxide (CO) is imperative. We have fabricated sensors comprising gold nanoparticle-loaded cerium oxide (Au–CeO₂). The morphology and elemental composition of the sensing material have been characterized using XRD, FESEM, TEM and XPS. The performance of the Au–CeO₂ sensors has been studied for the detection of CO in the concentration range of 10–30 ppm in air. The response and recovery transients of conductance have been modeled using two-site Langmuir adsorption kinetics. In the presence of 30 ppm CO, the calculated response times for two energetically different adsorption sites, CeO₂ surface and Au/CeO₂ interface are 9 s and 7 s, respectively. Finally, an exponential correlation between the gas concentration and the time constants has been derived.