IMPROVEMENT IN ACETYLENE SENSING PROPERTIES OF ZINC OXIDE NANOWIRES EMBEDDED WITH GOLD NANOPARTICLES

Abstract

In this work, acetylene sensing properties of ZnO nanostructures were investigated and compared to ZnO nanowires embedded with gold nanoparticles. Firstly, zinc films were thermally oxidized to form ZnO nanowires (ZnO NWs) at 700°C for 10 hours. Next, gold nanoparticles (Au NPs) were embedded onto the surface of ZnO NWs by photoreduction of HAuCl₄ under UVA irradiation (wavelength of 365 nm) for 10 minutes. ZnO NWs and ZnO NWs/Au NPs were then fabricated as acetylene sensor with active area of 9 mm². Au electrodes were patterned on the sensing layer by screen printing of electrical conductive gold paste. Finally, sensing properties were investigated at 0.1-2.5 Vol.% acetylene mixed normal atmospheric air and observed at operating temperature of 250-450 °C. It was found that the morphology of ZnO nanostructures were comprised of nanowires branched into their ZnO bases. The cylindrical diameter of ZnO nanowires was 50-200 nm. After photodeposition, 1.53 atom% of Au NPs were embedded onto their ZnO nanowires. The result ofacetylene sensing investigation showed that an embedding Au NPs onto ZnO NWs caused to increase the sensor response of about 1.7088, whereas ZnO NWs had the sensor response of about 1.0201. Accordingly, the improvement of sensor response can be explained in terms of the reaction rate constant by considering the catalytic effect of Au.