The Effect of Calcination Temperature Variation on the Sensitivity of CO Gas Sensor from Zinc Oxide Material by Hydrothermal Process

Carbon monoxide (CO) is a poisonous gas and could be lethal towards human. A sensitive CO gas sensor isnecessary to prevent accidents caused by CO gas. ZnO is a semiconductor material having many applicationsincluding gas sensors. However ZnO is rarely reported to be used as CO gas sensor material. Therefore, in thisresearch, CO gas sensor has been prepared from ZnO material synthesized via hydrothermal process at 100°C for24 hours using ZnCl2 powder and NH4OH solution. The resulted ZnO gel was subsequently dried andspin-coated on a glass substrate. The ZnO-coated glasses were then calcined at various temperatures of 500°C,550°C, and 600°C for 30 minutes. Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD),Brunauer-Emmet-Teller (BET) analysis were used to characterized the morphology, structure and active surfacearea of ZnO. The sensitivity of the ZnO material towards CO gas was measured using a potentiostat in achamber with operating temperatures 30°C, 50°C, and 100°C with each of gas concentration 10 ppm, 100 ppm,250 ppm, and 500 ppm. It was found that the sample calcined at 550oC showed the highest sensitivity towardsCO gas (0.82) due to the highest active surface area (47.2 m2g-1). It was also observed that the sensitivityincreased with the increasing of operating temperature and CO gas concentration.