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

Diah Susanti,Hariyati Purwaningsih,Lukman Noerochiem,George Endri Kusuma,Ridhwan Haliq

doi:10.5539/mas.v9n7p114

Diah Susanti, Hariyati Purwaningsih + Show 3 more

Open Access

https://doi.org/10.5539/mas.v9n7p114

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Abstract

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.

Highlights

Carbon monoxide (CO) gas is one of gases which harmful to human life
As we have discussed in the previous report (Susanti et al, 2014(d)), according to the TGA/DSC measurement of ZnO gel after hydrothermal process, we found two exothermic peaks at 530°C and 600°C shown the beginning of ZnO crystal and phase formations
CO gas sensor has been prepared from thin film of ZnO synthesized via hydrothermal process, spin-coated on top of glass substrate and followed by calcination at various temperatures 500, 550 and 650°C

Summary

Introduction

CO gas is one of gases which harmful to human life This gas is colorless, odorless and insoluble in water. In our previous work (Susanti et al, 2014(a) and 2014(c)), we have used WO3 semiconductor as a material for CO gas sensor. Besides WO3, ZnO is a semiconductor having many applications including gas sensors (Calestani et al, 2010, Hung, et al, 2010 and Liu, et al, 2008) and Dye Sensitized Solar Cell (DSSC) Susanti, et al, 2014(d). It has a band gap of 3.37 eV at room temperature (Tak et al, 2013), wider than WO3 of 2.6 – 3 eV (Gillet et al, 2004). The advantages of having a large band gap are capabilities to survive on high voltages and large electric fields and to operate at high temperature

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