Well-Aligned ZnO Nanorods Assisted with Close-Packed Polystyrene Monolayer for Quartz Crystal Microbalance

Zinc Oxide (ZnO) is known to be a promising material for sensing devices due to its piezoelectric properties. Recently, Quartz crystal microbalance (QCM) has emerged as widely promising sensor platforms owing to their high sensitivities and ease of measurements. In particular, the alignment of ZnO nanostructures into ordered nanoarrays is expected to improve device sensitivity due to the large surface area which can be utilized to capture significant quantities of gas particles. We synthesized nanostructures by adjusting the interval distances of the arranged ZnO nanorods using polystyrene (PS) monolayer. At this time, the diameter of polystyrene is 800 nm. Therefore, ZnO nanorods were grown on a quartz substrate with a patterned PS monolayer using a hydrothermal method. ZnO nanorods coated with polyvinylidene fluoride (PVDF) were fabricated and used for the detection of dimethyl methylphosphonate (DMMP) vapor. QCM was based on the frequency shifts due to the adsorption of DMMP vapor on the surface of the modified electrodes. By controlling interval distance of ZnO nanorods, the nanostructure was coated by PVDF. These results improve the sensitivity of QCM. The ZnO nanostructures were characterized by X-ray diffraction (XRD), Atomic force microscope (AFM), Field-emission scanning electron microscopy (FE-SEM), Energy dispersive X-ray spectroscopy (EDS) and Quartz crystal microbalance (QCM).