Ethanol sensor based on ZnO nanostructures prepared via microwave oven

The main demanding aim for many researchers is to reduce the operating temperatures as well enhance the sensing performance of metal oxide based alcohol gas sensor. Increasing the surface to volume ratio by controlling the morphology is one of the possible methods to reduce operating temperatures of sensing nanomaterials. A microwave-assisted method has been used for effecting the formation of porous nanostructure of metal oxide materials, such as CoO and SnO₂, in powder form. Here, by adopting the unique performance of a microwave-assisted-method, we realized the formation of highly porous ZnO nanostructures directly on the substrate surface, instead of in solution. The formation of ZnO nanoporous was confirmed by XRD, FE-SEM and XPS characterizations and subsequently tested for alcohol sensing performance. In addition, XRD revealed that ZnO nanoporous exhibited strong tendency to grow along (100) while generally retained the wurtzite framework. Ethanol sensing test was carried out at temperatures ranging from 25°C to 310 °C. This paper reports the gas sensing performance of ZnO synthesized as a porous nanostructure prepared by microwave method. In order to study the effect of the synthesis method and the morphology, ZnO nanorod was synthesized using a conventional hydrothermal method with comparable height with ZnO nanoporous (approximately 380-400 nm). The effects of these two different morphologies on alcohol sensing performance were investigated and discussed. The concentrations of alcohol can be detected at lower operating temperature using ZnO nanoporous sensor comparing to ZnO nanorod. The advantage of these experimental results is that the structure has significant effect on operating temperature as well as the performance of gas sensor.