Comparative study on the properties of ZnO nanowires and nanocrystalline thin films

Abstract

The microstructural, morphological, optical and water-adsorption properties of nanocrystalline ZnO thin films and ZnO nanowires were studied and compared. The ZnO thin films were obtained by a sol–gel process, while the ZnO nanowires were electrochemically grown onto a ZnO sol–gel spin-coated seed layer. Thin films and nanowire samples were deposited onto crystalline quartz substrates covered by an Au electrode, able to be used in a quartz crystal microbalance. X-ray diffraction measurements reveal in both cases a typical diffraction pattern of ZnO wurtzite structure. Scanning electron microscopic images of nanowire samples show the presence of nanowires with hexagonal sections, with diameters ranging from 30 to 90 nm. Optical characterization reveals a bandgap energy of 3.29 eV for the nanowires and 3.35 eV for the thin films. A quartz crystal microbalance placed in a vacuum chamber was used to quantify the amount and kinetics of water adsorption onto the samples. Nanowire samples, which have higher surface areas than the thin films, adsorb significantly more water

Structural and morphological investigation of (R)-α-phenylethylammonium-oxalate in bulk vs. nanowires on a modified substrate surface

“…ZnO structure is of the same, wurtzite type, both in nanowires and thin lms. 21,22 Atomic force microscopy (AFM), as one of the most popular scanning probe microscopy methods, enables imaging topography of almost any type of surface, such as polymers, ceramics, and composites. The substrate surface greatly affects the analysis of the sample, therefore, deposition on a very rough substrate disables the straightforward small particle size analysis.…”

Nanostructured ZnO thin films prepared by sol–gel spin-coating

“…Nanocrystalline ZnO is a material of great practical relevance because of its potential applications to the development of new gas and humidity sensors [1][2][3], UV detectors, optoelectronic devices [3,4], nanogenerators [5], etc. In addition, the porosity developed in ZnO thin films obtained by sol-gel favors other useful applications as substrates for catalysis, electrodes for solar cells, and for sensing of guest structures and biocompatible organic components.…”