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.