Effect of Incorporating Graphene Oxide in ZnO and Study of the Thermistor Applications of ZnO-RGO Film

Abstract

This research reported the effect of incorporating graphene oxide in the hybrid of ZnO and investigated the thermistor applications. ZnO-RGO were synthesized by the hydrothermal method and spin coated on glass to obtain the thin film. The SEM micrograph of ZnO-RGO showed mini ZnO nanorods decorated and formed on the RGO sheet. The adherence of the nanorods were improved as the loading mass of GO increased in the composite. ZnO-RGO had thermal sensing response of 3.1 respectively at 573K and showed improved electrical conductivity as temperature increased. ZnO sensors logged a negative temperature coefficient (NTC) value of 0.00236 /K and a sensitivity value of 0.01392 Ω/ K while ZnO-RGO had a NTC value of 0.00248139 /K (which is higher than values obtained in literature for silver and palladium based graphene composites) and a sensitivity value of 0.00769 Ω/ K. A value of 0.0561eV was obtained for the activation energy of ZnO sensor while 0.0615 eV was obtained for ZnO-RGO. This research has confirmed that incorporating GO in ZnO increased the activation energy of ZnO-RGO thermistor, and consequently increased the thermal sensing response thus resulting in improved thermal sensing properties of ZnO. With an improved NTC, sensor response and activation energy, ZnO-RGO can replace Pd based RGO and Ag nanoparticles based RGO as thermistors.