Norsuria Mahmed

Room Temperature Synthesis of Magnetite (Fe3-δO4) Nanoparticles by a Simple Reverse Co-Precipitation Method

Magnetite (Fe3-δO4) nanoparticles with the size less than 30 nm have been synthesized by using a simple reverse co-precipitation method at room temperature. During the process, ferrous sulfate (FeSO4•7H2O) powder was used as an iron precursor, and ammonium hydroxide (NH4OH) as a precipitating agent. The experiment was carried out in ambient atmosphere without any surfactant added. In this method, the base solution for the precipitation process was adjusted to have a pH value suitable for the formation of the magnetite phase. The iron salt precursor was added into the solution during the synthesis by two different synthesis protocols. The phase, morphology and magnetic characteristic of differently synthesized magnetite particles were characterized by using an X-ray diffraction (XRD), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM). The morphologies of the particles were spherical or irregular in shape depending on the synthesis protocol used. Magnetic measurement shows that the particles are ferromagnetic at room temperature with relatively high saturation magnetization and low hysteresis. The saturation magnetization and magnetic hysteresis of the particles varied with preparation reaction conditions and the resulting oxidation state of the particles.

Self-Cleaning Technology in Fabric: A Review

This article gives an overview on photocatalytic self-cleaning technology on fabric resulting from titanium dioxide (TiO2) and zinc oxide (ZnO) as photocatalyst which decompose the organic stain into water and carbon dioxide (CO2) in presence of UV light source. The self-cleaning concept is useful in various application including the textiles materials which are normally used in daily life. This technology also can be developed in other application for instance medical textiles, athletic wear, and military uniform and also outdoor fabrics. Additionally, it is beneficial as it effectively conserves water and improves the appearance of the environment and in long term it will reduce energy, laundry cost and time as well.

Review on thermal insulation performance in various type of concrete

Thermal insulation concrete building plays an important role in environment sustainability especially energy saving buildings. Buildings are one of the largest consumers of energy worldwide. Therefore, significant energy saving can be realized by buildings with proper materials, design and operation. Thermal insulation systems are nowadays mostly applied for such building envelopes where the materials of load bearing structure such as concrete do not have a substantial thermal insulation capability. Thermal insulation in concrete are materials or combinations of materials that are used to provide resistance to heat flow, should have low conductivity for building application in order to represence of a temperature gradient, has an important effect on the heat exchange between the building interior and the ambiance. The aim of this paper is to review the thermal properties include thermal conductivity and specific heat on various types of concrete.

Influence of Hydrochloric Acid Concentrations on the Formation of AgCl-doped Iron Oxide-Silica Coreshell Structures

Silver chloride (AgCl) nanoparticles with the average size of about 45 nm have successfully been doped onto the iron oxide-silica coreshell surfaces by a simple room temperature wet chemistry method under ambient atmosphere. The Stöber process has been used to make the coreshell structure, followed by adsorption of Ag+ species on silica surface prior to the addition of hydrochloric acid (HCl) and polyvinylpyrrolidone (PVP). The concentration of HCl acid that was used to induce the growth of AgCl particles was varied from 0.12 mM to 12x103 mM of concentrations. Results showed that at a very high concentration of HCl (12x103 mM), large AgCl agglomerates (0.3-0.6 microns) with irregular cubic-like morphology were obtained while at a very low, 12 mM HCl concentration, 30-50nm AgCl particles having a uniform cubic morphology were observed. Concentrations below 12 mM result in irregular and nearly spherical morphology of AgCl particles with a smaller size (28-60 nm). UV-Vis absorption of the composite materials showed absorption in the visible wavelength indicating that Ag nanoclusters might coexist together with AgCl particles.

Effect of Annealing Temperature on Silver Doped Titanium Dioxide (Ag/TiO2) Thin Film via Sol-Gel Method

This study is conducted to investigate the effect of different annealing temperature on the growth of Silver doped Titanium Dioxide (AgTiO2) nanocrystalline thin films.AgTiO2 nanocrystalline thin films on silicon wafer have been prepared by sol–gel spin coating. The thin films were characterized for surface morphology and phase analysis by Scanning Electron Microscope (SEM) and X-ray diffraction (XRD. The films prepared by titanium tetraisopropoxide (TTIP) as the precursor under pH of 3.5 ± 0.5 and with annealing temperature of 300, 400, 500 and 600°C for 2h soaking time. X-Ray diffraction shows that only Ag/TiO2 thin film annealed at 600°C have anatase TiO2 phase. From SEM micrograph, there are cracks and pulled out thin film from the substrate, which were gradually minimize as the annealing temperature increase.

The Effect of Temperature on Anatase TiO2 Photoanode for Dye Sensitized Solar Cell

Dye sensitized solar cell (DSSC) is a well-known photovoltaic device that is used for low power application. One of the main components for DSSC is semiconductor material photoanode which will provide the pathway for electron transportation and thus determine the energy conversion efficiency of the DSSC. The most commonly used material for the semiconductor photoanode is titanium dioxide (TiO2). TiO2 is a semiconductor material with wide bandgap material that is existed in three crystalline phase; rutile, anatase and brookite. This paper emphasizes the best annealing temperature for commercialized TiO2, 98% anatase powder where the temperature varies from 300 oC – 600 oC. Through this research, the best annealing temperature for anatase TiO2 photoanode is at 420 °C (0.094%) with the crystallite size of 18.76 nm and particle size of 19 nm that is favorable for the dye attached and thus enhances the energy conversion efficiency of the DSSC.

Synthesis and Characterization of Ag/TiO2 Thin Film via Sol-Gel Method

Ag/TiO2 thin films were prepared via sol-gel spin coating method. Structural, surface morphology and optical properties were investigated with the addition of two different amount of silver (Ag). X-ray diffraction pattern shows the sample with pure TiO2, the only phase presence was brookite TiO2. When the Ag content added into the solution, the phase existed for the samples with TiO2 doped 0.5g Ag and TiO2 doped 1.0g Ag were anatase TiO2 with no peak corresponds to Ag phase. The surface morphology of film was characterized by scanning electron microscopy (SEM). The films were annealed at 450 °C and it shows non-uniform films. The films have a large flaky and cracks film which was attributed to surface tension between the film and the air during the drying process. When the solution of sol was added with Ag content, it shows the porous structure with flaky-crack films. With the increasing of the Ag content from 0.5g to 1.0g, the structure is more porous and it is good for the photocatalytic activity. The UV-Vis spectra shows that the film exhibits a low absorbance which was due to the substrate is inhomogeneously covered by the flaky-crack films.

Synthesis of Nanosized Silica and Silver-Doped Silica Nanoparticles for Heat Transfer Fluids Applications

The nanosized silica (SiO2) with the size less than 100 nm have successfully been prepared by hydrolysis and condensation of tetraethyl orthosilicate (TEOS) via a modified Stöber method at room temperature. The experiment was conducted by controlling the amount of the catalyst used, i.e., ammonium hydroxide (NH4OH). The morphology observation of the synthesized silica nanoparticles was conducted by using a transmission electron microscope (TEM). It was found that the size of the silica depending on the amount of the catalyst used, with homogenous size ranging from 10 to 360 nm. The doping of silver nanoparticles was done by mixing the synthesized silica with the silver ions (Ag+) solutions. Then the sample was annealed for 75 min which results in the nucleation of the silver nanoparticles less than 20 nm onto the silica surfaces, depending on the temperature used.