Low-humidity sensing properties of diamine- and β-cyclodextrin-functionalized graphene oxide films measured using a quartz-crystal microbalance

The low-humidity sensing properties of functionalized graphene oxide (GO) thin films with COOH, CONHC2H4NH2, CONH(C2H4)3NH2 and β-cyclodextrin (β-CD) functional groups were studied by using a quartz crystal microbalance (QCM). The functionalized GO thin films were characterized by atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR). Water vapor molecules were easily adsorbed by the functionalized GO thin film with COOH functional group, but barely adsorbed by the film with the CONH(C2H4)3NH2 functional group owing to the difference between the difference in the stability of the hydrogen bonds between water molecules and functionalized GO thin films. Adsorption dynamic analysis and molecular mechanical calculations (of the association constant) were performed and the functional groups on the GO were found to affect their humidity-sensing properties (sensitivity), especially at low humidity.