Low-Temperature Detection of Carbon Monoxide With Enhanced Sensitivity Using Ag-Loaded ZnO/rGO—Modeling, Simulation, and Validation

Rapid monitoring of carbon monoxide (CO) is crucial because of its detrimental effects on human health and other living organisms. Metal oxide semiconductor (MOS) nanostructures are identified as promising materials for gas sensors, but they have several limitations, such as inadequate selectivity, high operating temperature, and substantial power consumption. This article presents the design, simulation, and evaluation of a CO gas sensor that utilizes silver-loaded zinc oxide/reduced graphene oxide (ZnO/rGO). Operating conditions for the sensor have been optimized for high performance and fast response/recovery times. An optimized load of 1.5 wt.% of Ag into ZnO/rGO with a weight ratio of 2:1 allows the sensor to detect CO with a response magnitude of 6.26 even at a temperature as low as
$30~^{\circ }$
C. Furthermore, it shows a response time of 25 s and a recovery time of 49 s when exposed to a CO concentration of 30 ppm. The incorporation of 1.5 wt.% Ag into ZnO/rGO also improves its selectivity toward CO against various interfering gases. The improvement in sensor performance is attributed to the high surface area of rGO, which promotes the adsorption of CO gas molecules and the catalytic effect of Ag content which reduces the activation energy. The simulation result agrees well with the experimental data, demonstrating superior sensitivity at low temperatures. This research can facilitate identifying appropriate sensing materials and optimal designs for high-performance gas sensors and forecast their behavior before the fabrication process begins.