Low temperature carbon monoxide gas sensor based on Ag-Co3O4 thick film nanocomposite

Co3O4 nanoparticles (NPs) were prepared via a facile coprecipitation method. The carbon monoxide (CO) sensitivity of the as-prepared material was studied at different temperature (50-200 °C) and at different gas concentration (5-1500 ppm). In order to improve the sensor sensitivity, silver (Ag) NPs were loaded on Co3O4 nanoparticles through solution impregnation technique. The crystalline structure, thickness, morphology and elemental composition of the sensing films were characterized by XRD, FE-SEM and EDX analysis. Our results indicated that Ag NPs addition has increased the sensitivity of the Co3O4 NPs based CO sensor. Improving effect of Ag was discussed through activation energy evaluation and energy band diagram. It was concluded that Ag NPs addition, has facilitated CO sensing by decreasing the activation energy and also through the electronic mechanism in the energy levels of Ag-Co3O4 heterocontact.