Supakorn Pukird

Growth and Characterization of SnO2 Nanostructures by Vapor Transport Technique

Tin dioxides (SnO2) nanostructure can be grown by vapor transport techniques through a vapor-liquid-solid (VLS) mechanism. The gas flowing have been effect on the evolution of various sizes and shapes of nanostructure materials. The crystalline structures of SnO2 materials were investigated by X-ray diffraction (XRD) spectroscopy. XRD patterns of samples exhibited tetragonal phase. The characterization of synthesized products was performed by scanning electron microscopy (SEM). The controlling of process gas flow, showed the various kinds of nanostructures such as nanobelts, nanowires and nanobars of SnO2. The Raman spectra of single-crystalline rutile SnO2 nanostructures were studied, the vibration modes were observed corresponded to the typical feature of the SnO2 nanostructure. A room temperature photoluminescence (PL) spectrum of SnO2 material exhibited visible emission.

Zinc Oxide Nanostructures Synthesized by Thermal Oxidation of Zinc Powder on Si Substrate

ZnO nanowhiskers were formed by a simple oxidation of metallic zinc powder 99.9% at different temperatures from 400-900 °C for 2 hours on the silicon substrate. The result can be obtained after the thermal oxidation process, the ZnO nanowhiskers with different morphologies at different temperatures in which these morphologies and composition of ZnO nanostructures were characterized by scanning electron microscope, (SEM) and X-ray diffraction, XRD. It was found that the products were nanowhiskers, the structure are triangular shapes with average width of 10-50 nm at the root, 10-30 nm at the tip and length in the range of 1-3 μm was observed by SEM. Temperature in the range of 600-700 °C was suitable for the preparation of ZnO nanowhiskers. At higher temperature of 800 °C, the concentrations of ZnO structures become lower and stronger. At the oxidized temperature of 900 °C, ZnO nanowhiskers were not found and surface morphology become to porous. These results indicate that the oxidation rate is faster than the diffusion rate of Zn vapor on the surface of ZnO nuclei.

Performance and Stability of Dye-sensitized Solar Cells with Quasi-solid State Electrolytes base on N-methyl-quinoline Iodide

We have fabricated dye-sensitized solar cells (DSSCs) with quasi-solid state electrolytes base on N-methyl-quinoline iodide and studied the performance and stability of the cells at different temperatures. The quasi-solid state electrolytes were prepared from polymer gel electrolyte based on N-methyl-quinoline iodide and iodine. Pure-anatase nanocrystalline TiO2 films with absorption of standard N719 dye were employed as working electrodes. The maximum efficiency of the solar cells was 4.5 % under incident light of 100 mW/cm2. The cells also showed excellent stability for several months under irradiation of sunlight. The ionic conductivity of the electrolytes and the performance of the cells at different temperatures were presented.

Synthesis of Zinc Oxide Nanowire-Nanowall-Like Hybrid Structures on Graphene

ZnO nanowire-nanowall-like hybrid structure on graphene was synthesized with a simple chemical vapor deposition technique. This was done without a template by utilizing a catalyst to control the growth time and condensation. The surface morphology of nanostructure was characterized by using a field emission scanning electron microscope (FE-SEM). We found that the ZnO nanowire-nanowall-like hybrid structure was uniformly deposited on the graphene. The extremely strong ZnO (0002) peaks were observed by using x-ray diffraction (XRD). This method showed the preferred (0001) orientation and high crystalline quality of the ZnO nanostructures. The optical properties were investigated utilizing photoluminescence (PL). These results showed the strong green-yellow emission attributed to the robust inner reflection and scattering. This simplified method has great potential in synthesizing uniform ZnO nanowire-nanowall-like hybrid structures on graphene. These nanostructures may have important applications in new types of flexible gas sensors or other fields demanding high surface area materials.

Zinc Oxide Nano Walls Synthesized by Chemical Vapor Deposition

ZnO nanowalls were synthesized by chemical vapor deposition at temperature of 650 °C for 1 hour on the silicon substrate. The morphologies of samples were characterized by scanning electron microscopy (SEM). The result from X-ray diffraction (XRD) confirmed that the ZnO nanowalls were vertical c-axis orientation. A room temperature Photoluminescence peak at 378 nm is ultraviolet emission (UV) and the broad peak at wavelengths around 450-650 nm is corresponding to the green emission of ZnO nanostructure. This synthesis may be applicable for gas sensor or solar cells.

Growth of SiC and SiO2 Nanostructures Prepared from Rice Husk Ash Using Carbon-Metal Assisted

This work suggested the growth of SiC and SiO2 nanostructures from heating of rice husk ash and carbon-metal assisted. The rice husk was boiled in 1 M hydrochloric acid solution with temperature of around 90 °C for 1 hour, and then washed in distilled water and dried under the sun. The dried acid-treated rice husk was burned in the furnace with normal air for 1 hour, then high purity SiO2 was produced. The high silica ash mixed with Cu or SnO2 powder and coconut shell charcoal were grounded for mixtures powder. The mixtures powder and Si substrates were placed on the alumina boat and put in the middle of furnace. The furnace was heated at high temperature under atmosphere of argon gas. The heated products and Si substrates were studied by X-rays diffraction and scanning electron microscope. The SiC and SiO2 nanostructures were observed.

Studies on the Preparation and Gas Sensing Properties of SnO2 Nanostructures at Room Temperature

The SnO2 nanostructures have been synthesized by carbon-assisted growth at 800 oC for 3 hours. Using high pure tin powder as the source materials. The synthesized products were investigated by stereo microscope, X-rays diffraction (XRD) and scanning electron microscopy (SEM). XRD patterns show that the prepared products are tetragonal-structures with the lattice constant a = 0.4718 nm and c = 0.3187 nm. SEM images indicate that SnO2 nanowires are about tens of micrometers in length, 80-100 nm in width. The diameter of SnO2 nanoparticles vary from 10 nm to 100 nm. The synthesized products are high sensitivity and fast response time to ethanol gas at room temperature.

Gas Sensing Properties of CuO Nanostructures Synthesized by Thermal Evaporation of Copper Metal Plate

CuO nanostructures were synthesized by thermal evaporation method. Using Cu metal plate at temperature of 400oC for 24 hrs in one atmosphere of oxygen and studied structural and gas sensing properties. The CuO nanostructured were investigated by the stereo microscope (image analyzer), X-ray diffraction, scanning electron microscope. The diameter of CuO nanowires vary from 10 nm to 50 nm and length of several 10 micrometers. The sensitivity of CuO nanostructures and response were performed at room temperature for ethanol and CO2 sensor.

The Effects of Substrate Temperature on Optical Properties and Surface Morphology of Nickel Phthalocyanine Thin Films Grown by Organic Evaporator System

Thin films of Nickel Phthalocyanine (NiPc) are prepared at a base pressure of 10-6 mbar using Organic Evaporator System. The films are deposited onto the glass substrate at various temperatures of 100 0C, 120 0C, 140 0C and 160 0C. Crystalline of NiPc thin films was investigated by X-ray diffraction (XRD) spectroscopy. XRD patterns exhibit to become aggravated crystalline films as monoclinic structure. Surface morphology of NiPc thin films was characterized by field emission scanning electron microscope (FE-SEM). FE-SEM micrographs indicate that fiber-like morphology of NiPc is enhanced with increasing substrate temperature. The optical absorption spectra of these thin films are measured. Present studies reveal that the Q-band of NiPc thin films appears as the change of electron energy level. Absorption spectra obtained from UV-vis of deposited NiPc are declined as the substrate temperature is risen.

Fabrication of three-layered ZnO-CuO-SnO2 hybrid nanostructures n-p-n hetero-junctions

ABSTRACT Three-layered ZnO-CuO-SnO2 hybrid nanostructures n-p-n hetero-junctions were synthesized for the first time by 3-step chemical vapor deposition on SiO/Si substrates. Starting materials made of Cu, Zn and Sn powder mixed with carbon charcoal were heated at various temperatures and pressures under atmosphere of O2 and Ar. The prepared samples were investigated by field emission scanning electron microscope (FESEM), X-rays photoemission spectroscopy (XPS), and I-V characteristic curves. The results reveals the formation of CuO hollow microspheres with branching lines, ZnO nanowires, and SnO2 nanorods in which establish the three layers of the hetero-junctions. I-V characteristics exhibit rectifying behavior of hetero-layered semiconductors.