Multi-Walled Carbon Nanotubes/Graphene Oxide Composites for Humidity Sensing

Based on good dispersion of multi-walled carbon nanotubes (MWCNTs) in graphene oxide (GO) solution, MWCNTs/GO composite film was fabricated on a quartz crystal microbalance (QCM) by a simple drop-casting method. The composite responds quickly to relative humidity changes. The QCM with MWCNTs/GO coating showed the highest sensitivity among the QCMs coated with different films (MWCNTs, GO, and MWCNTs/GO). By monitoring changes in both the resonant frequency and impedance of the QCM sensors, it is found that the motional resistance and the quality factor (Q) of the QCM with MWCNTs/GO film have remarkable changes as compared with the QCM with GO film, which is suspected to be related with the viscosity of the sensing film. Meanwhile, the addition of MWCNTs may enlarge the distance between the GO sheets in composites and might be beneficial to the diffusion of water molecules. This study demonstrates that the MWCNTs/GO composite could be used for high sensitive humidity detection.