Chokchai Kahattha

Synthesis and characterization of carbon nanotube/zinc oxide composites

ZnO/CNT composites were successfully prepared by sol-gel method based on zinc acetate 2-hydrate (Zn(CH3COO)2·2H2O), absolute ethanol (C2H5OH) and diethanolamine (HN(CH2CH2OH)2, DEA) as a solvent and sol stabilizer. Carbon nanotube with 0.1, 0.3 and 0.5 %w/v were loaded into the prepared sol. Then the mixed sols were dried at 100 °C and annealed at 300, 350 and 400 °C in ambient air. The crystalline structure and surface morphology ZnO/CNT composites were characterized by XRD and SEM. The preliminary results shown that the ZnO/CNT composites with CNT-doped 0.1 %w/v exhibited hexagonal wurtzite structure with (100), (002), (101), (102) and (110) peak orientation plane for all annealed temperatures. In addition, ZnO grain sizes increased with annealed temperatures. SEM results shown that ZnO covered the CNT surface.

Effect of Sonication Time and Calcination Temperature on Physical Properties of Titanium Dioxide Synthesized via Sonochemical-Assisted Process

Titanium dioxide nanoparticles (TiO2) were successfully synthesized via a sonochemical-assisted process using titanium isopropoxide as the titanium sources and calcination process at 300-500 °C. The effect of sonication time and heat treatment temperature on structural and nanostructure properties of the nanoparticles were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM) and transmission electron microscope (TEM). The XRD and Raman results indicated that the crystalline of as-sonochemically synthesized TiO2 nanoparticles corresponded to anatase phase of TiO2 after sonication for 30 mim. The high quality crystalline anatase phase and increasing of crystalline size can be obtained after calcinations process.

Influence of annealing temperature on optical properties of fluoride doped tin oxide films grown by the sol-gel spin-coating method

ABSTRACT Fluoride-doped Tin Oxide (FTO) thin films were deposited on glass and silicon substrates by the sol-gel spin-coating method using stannic chloride pentahydrate (SnCl4·5H2O) and ammonium fluoride (NH4F) as starting precursors for Sn and F sources. As-deposited films were annealed at different temperatures ranging from 300–600°C. The effect of annealing temperature on structural and optical properties of FTO thin films including crystallinity, surface morphology, optical transparency, optical reflectivity and optical band gap are investigated by X-ray diffraction, scanning electron microscopy and UV-VIS spectrophotometry. The XRD results suggest that the prominent peak in the (110) orientation can be indexed to the polycrystalline SnO2 structure without any impurity phase caused by fluoride doping. The transmittance spectra of fluoride-doped tin oxide thin films show good transparency in the visible region with noticeable variation in its structural and optical reflectance properties depending on annealing temperature.

Titanium dioxide/Vanadium oxide nanocomposites synthesized via sonochemical and hydrothermal process for energy storage application

V₂O₅/TiO₂ nanocomposites were synthesized via sonochemical and hydrothermal process. At first, titanium dioxide (TiO₂) nanopowders were synthesized by sonochemical process using titanium isopropoxide as a titanium source. Meanwhile, hydrothermal process was carried out to modify the structure of commercial V₂O₅ powder to be nanorod-like structure V₂O₅ with increasing specific surface area. Structural and morphological properties of the composites were characterized by XRD and SEM, respectively. The XRD results indicated that the crystalline of the composites corresponds to anatase and orthorhombic structures of TiO₂ and V₂O₅, respectively. The significant variation of charge storage properties of the nanocomposites under ultraviolet irradiation were obtained by varying V₂O₅ content in the composite. Results suggest that V₂O₅ loaded into the nanocomposite play a key role as a storage material of photoelectron generated by TiO₂ illuminated under ultraviolet.

Effects of Reductant on Physical Properties and Formation of Vanadium Oxide Compounds Prepared by Hydrothermal Route

Vanadium oxide nanostructures were successfully synthesized by hydrothermal process using V2O5 as a starting source material. The process was conducted at 120°C for 48 h using different reductants including n-butanol and acetylacetone. The essential physical properties of as-synthesized products were characterized by XRD, FT-IR spectroscopy, SEM and TEM. The XRD and Raman results revealed that the crystalline structure and phase of the samples are highly dependent on the reductant types. The SEM images enclose that as-prepared samples possess different morphologies depending on different reactant. The phase transformation from V2O5 to VO2 can be also carried out by this process with assistance of these reactants.