Zinc Oxide (ZnO) is considered as the most promising metal oxide because of its numerous utilization in different fields. One of the most important application of ZnO is for gas sensing. In order to improve the sensitivity of materials, it is observed that high aspect ratio nanowires possess better sensing capability due to the high surface area and uniformity. The purpose of this study is to fabricate high aspect ratio ZnO nanowires by vacuum die casting and using Anodic Aluminium Oxide (AAO) as a template and to investigate their gas sensing performance.
Firstly, AAO was fabricated by two-step anodization from aluminium. Then after observing AAO nano porous structure in SEM showing that the average pore diameter is 100nm, zinc was injected into AAO pores by vacuum die casting. The casting was carried out at the temperature of 500°C for 40 minutes respectively. Finally, the Zinc along with AAO is oxidized to form Zinc Oxide nanowires. The optimal condition for oxidation of zinc was found out to be 420°C for 48 hours. After dissolving AAO with acid ZnO nanowires were collected. Finally, ZnO nanowires were spread over silicon substrate to observe electrical properties and gas sensing.
The porous structure of AAO was observed under SEM. Then after zinc casted into AAO, SEM was performed to observe success of casting. EDS and XRD analysis were also performed after oxidation of Zinc. EDS, XRD and TEM were also performed to further verify the purity of ZnO nanowires after dissolving AAO with acid. The average diameter of ZnO nanowires is 100nm. IV curves of different samples were obtained to further classify the ZnO nanowires and study the electrical behavior of single nanowire. Finally, gas sensing response were observed for 500ppm of H2 gas. From the observation, it can be concluded that ZnO nanowires fabricated by vacuum die casting has a potential to be utilized for nanowires gas sensing device.

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