High-selectivity eco-friendly hydrophilic gas sensor using the functional groups of graphene oxide coated on an aluminum oxide nanostructure

Abstract

We propose an optical gas sensor using anodic aluminum oxide (AAO) and a graphene oxide (GO) layer to detect hydrophilic gas. In the proposed sensor, GO reacts with the induced gas to cause a change in the refractive index of the AAO surface, which can be optically detected by measuring the reflected wave on the surface of the device. By using the high reactivity of GO to hydrophilic gases owing to reactors such as hydroxyl and carboxyl groups, the GO-coated AAO-based sensor showed high sensitivity of 15 a.u./ppm for the hydrophilic gas, dimethylamine gas, and low sensitivity for the hydrophobic, toluene. The AAO was fabricated by second anodization, a hard anodization, and the GO layer was easily fabricated by using the spin-coating method. Through analysis of scanning electron microscopy, atomic force microscopy images and energy dispersive X-ray microanalysis, the GO thin film formed on the AAO was confirmed, demonstrating that a sensor with high selectivity for hydrophilic gas was fabricated.