Search

Trivalent metal-doped TiO2 thin films have been extensively investigated in gas sensor applications. The trivalent metal dopants are Al, Y and Gd. The trilayer fabrication of a gas sensor consists of a thin film, sputtered TiO2 and Au nanoparticles. The characteristics of the gas sensing properties are strongly correlated with the annealing temperature, film thickness, type of doping and deposition method. The subsequent properties are presented - the crystalline structure, grain size, roughness, strain, stress and defects. Thin films have been developed with concentrations of O2 gas up to 10 sccm. A response time for O2 gas in milliseconds was obtained at room temperature. Al doped TiO2 thin film have a faster response time operating at room temperature compared with other thin films. Oxygen vacancy defects also contribute to the speed of the response time for a gas sensor. [ABSTRACT FROM AUTHOR]

Titanium dioxide (TiO2) has been intensively investigated for solar hydrogen conversion via photocatalytic and photoelectrochemical water splitting. However, the performance of TiO2 photocatalyst for hydrogen generation is low due to the rapid electron-hole recombination and its wide band gap (3.0-3.2 eV) which is only feasible for UV light absorption of solar spectrum. There are various strategies have been used for TiO2 modification to harvest the sunlight and improve the surface chemical reaction between TiO2 and H2O for water splitting. Among the TiO2 modification strategies, intrinsic point defects such as vacancies and interstitials in TiO2 have been proven to improve the TiO2 properties for photo-catalytic activity. In this article, the recent progress achieved in defective TiO2 with intrinsic point defects for photocatalytic hydrogen evolution and photoelectrochemical water splitting has been reviewed. The fabrication methods of defective TiO2 along with their structural, optical, and charge carrier properties have been introduced. It has appeared that the intrinsic point defects are a promising strategy to improve the performance of TiO2 for photocatalytic hydrogen production, and more efforts are stiH needed to improve the TiO2 performance for photocatalytic hydrogen production in this area of research. [ABSTRACT FROM AUTHOR]

A very simple nanocomposite material has been in-situ manufactured from an aqueous polystyrene nanospheres dispersion and cadmium (Cd) metal nanoparticles. The manufacturing was performed by using a high frequency of 40 kHz ultrasonic (US) agitation for 45 minute at atmospheric pressure and at room temperature 20 °C. No chemical reducing agent and surfactant added in this manufacturing technique due to the US could reduce Cd2+ ions of cadmium nitrate tetrahydrate to Cd atomic metals nanoparticles whereas water molecules could act as a pseudo stabilizer for the manufactured material. A thin film was manufactured from aqueous colloidal nanocomposite material of Polystyrene nanospheres/Cd metal nanoparticles (PSNs/CdMNp) fabricated on a hydrophilic silicon wafer. The thin film was then characterized by a JEOL-FESEM for its surface morphology characteristic and by ATR-FTIR spectrometry for its molecular change investigation. It could be clearly observed that surface morphology of the thin film material was not significantly changed under 633 nm wavelength continuous laser radiation exposure for 20 minute. In addition, its ATR-FTIR spectra of wave number peaks around 3400 cm-1 have been totally disappeared under the laser exposure whereas that at around 699 cm-1 and 668 cm-1 have not been significantly changed. The first phenomenon indicated that the hydrogen bond existed in PSNs/CdMNp material was collapsed by the laser exposure. The second phenomena indicated that the PSNs phenyl ring moiety was not totally destroyed under the laser exposure. It was suspected due to the existence of Cd nanoparticles covered throughout the spherical surface of PSNs/CdMNp material particles. Therefore a nice model of material structure of the mentioned PSNs/CdMNp nanocomposite material could be suggested in this research. It could be concluded that this research have been performed since the material structure model of the manufactured PSNs/CdMNp nanocomposite could be drawn and proposed. [ABSTRACT FROM AUTHOR]

Abstract: Porous Polystyrene nanospheres (PSNs)-Cd metal thin film of about 375.72 angstrom (Ǻ) on hydrophilic silicon wafer has been successfully fabricated from its liquid colloidal prepared by 40 KHz ultrasound for 45minute at room temperature. This porous fabrication was aiming to confirm the proposed structure of PSNs based-porous thin film models depicted in Fig.1. Surface morphology of the porous thin film explored with a field emission scanning electron microscopy (FESEM) showed that Cd metals atomic particles might be deposited on the PSNs particles surface so that they could enhance the porosity of the thin film material. Absorption capability of the porous thin film assayed using both ultraviolet-visible (UV-Vis) and infrared (IR) light proved that Cd metals atomic particles were a main part of the porous thin film which could enhance significantly the absorption performance. It could be concluded that both kind of nano- sunken and nano-wells unique binding sites might have been generated inside the pores during fabricating them. [Copyright &y& Elsevier]

Zinc oxide (ZnO) is an emerging optoelectronic material in large area electronic applications that are due to its various functional behaviors. We present the fabrication and characterizations of ZnO nanorods. The ZnO nanorods were synthesized using sol-gel hydrothermal technique on oxidized silicon (Si) substrates. In the fabrication of ZnO nanorods, the oxidized Si substrates were immersed in ZnO aqueous solution for different durations ranging from 3 hours to 5 hours. The surface morphologies of the ZnO nanorods were examined using scanning electron microscope (SEM). In order to investigate the structural properties, the ZnO nanorods were measured using X-ray diffractometer (XRD). The optical properties were measured using ultraviolet-visible (UV-Vis) spectroscopy. The effect of the immerse duration on the material properties of the realized ZnO nanorods will be revealed and discussed in this paper. [ABSTRACT FROM AUTHOR]

The chrysanthemum-like ZnO crystal has been grown by dry oxidation process in the sol-gel method. The samples have been characterised using SEM and XRD. The surface morphology of SEM result shows that the structure is like a chrysanthemum flower. The chrysanthemum-like crystal has been synthesised and composed of one-dimensional nanorods which have hexagonal wurtzite structure. It is also shown that the nanorods were preferentially grown along the [001] direction. In this paper, the growth mechanism and synthesis technique of chrysanthemum-like nanostructured ZnO are explained in detail. [ABSTRACT FROM AUTHOR]