Growth and Characterization of ZnO, SnO2 and ZnO/SnO2 Nanostructures from the Vapor Phase

Abstract

Zinc oxide (ZnO), tin dioxide (SnO 2 ) and compounds ZnO/SnO 2 (ZTO) nanostructures have been synthesized successfully from the vapor phase without a catalyst using three different approaches. XRD analyses showed that ZnO with a wurtzite crystal structure, SnO 2 with a rutile crystal structure and zinc stannate (ZnSnO 3 ) and/or dizinc stannate (Zn 2 SnO 4 ) were condensed from the vapor phase when Zn and/or Sn metal powders or their oxides individually or mixed were used as the starting materials. The formation of either zinc or dizinc stannate was controlled by the Zn/Sn ratio and growth technique. SEM and TEM investigations showed that ZnO grew mainly in the form of wires, rods and belts. These are believed to be originated from the common tetrapod structure of ZnO. While SnO 2 grew in the form of tetragonal rods with rectangle-like cross section and nanoparticles, ZTO grew in the form of nanobelts. The final length, width and thickness were as low as 40, 10 and 5 nm, respectively. The driving forces for growth of nanowires, nanorods, nanobelts, and nanoparticles were found to be vapor density or supersaturation, temperature, pressure and location of deposition from the source materials. The optical absorbance and photoluminescence spectra of all samples showed excitonic character at room temperature implying good crystal quality, and high photocurrent properties suggesting possible applications in nanoscaled functional devices such as optoelectronics and gas sensors.

Enhanced Ethanol Gas Sensing Properties of SnO2-Core/ZnO-Shell Nanostructures

“…In some cases, vacuum conditions [ 38 ] and strict temperature control [ 39 ] are necessary for the formation of nanowires in the vapor phase, because some materials may not sublimate under ambient pressure (normal atmosphere). An effective way to generate the necessary vapor phase under ambient pressure is to add activated carbon [ 40 ]. In our previous work [ 41 ], we reported the formation of SnO 2 -core/ZnO-shell nanowires at a growth time of 30 min and hierarchical SnO 2 -core/ZnO-shell nanostructures at a growth time of 120 min.…”

Fabrication of Microfibre-Nanowire Junction Arrays of ZnO/SnO2 Composite by the Carbothermal Evaporation Method

“…Prior to each deposition run, time was allowed for the tube to heat up to the predefined temperature of 1100 o C. Initially, commercial zinc oxide (ZnO, 99.999%, Alfa Aesar), tin dioxide (SnO2, 99.999%, Alfa Aesar) and graphite powder (C, 99.999%, Alfa Aesar) with a weight ratio of 1:1:2 were intimately mixed by grinding the powder mixture for 15 minutes and then used as the source material. The graphite was used in a threefold excess 3X [25], where X is the stoichiometric amount needed for the reduction of 1 mol of ZnO or SnO2. During the deposition, nitrogen gas was introduced into the furnace tube at a flow of 2 L/min.…”

Multiporous nanofibers of SnO2by electrospinning for high efficiency dye-sensitized solar cells

“…[18][19][20] Considerable efforts have been devoted to develop its nanostructures with diverse morphologies and aspect ratios with an aim to enhance the specic surface area and further improve their properties. Nonconventional morphologies of SnO 2 , such as tetrapods 21 and owers, 13 have been synthesized from colloidal solutions with improved properties compared to their particulate or 1D analogues. SnO 2 nanowires and nanotubes are also developed using electrospinning technique with improved properties.…”