Advanced Materials Research Vol. 832

Abstract: Zinc acetate as starting material along with diethanolamine as a stabilizer and isopropyl as a solvent were used in ZnO precursor preparation while p-type silicon was used as a substrate in this work. ZnO thin films were deposited on silicon wafer by spin coating deposition method. Samples were annealed at different temperature in range 500°C to 800°C. In other to study the surface morphology of thin film, Field Emission Scanning Microscopic (FESEM) was employed for every sample. It was found that, the thin films are composed by ZnO nanoparticles with size of about 18.3 nm to 32.95 nm. Topology of ZnO thin films was characterized by atomic force microscopy (AFM). In other to study the photoluminescence properties, 325 nm of xenon lamp was used as sources within range of 350 nm and 600 nm. It is found that two peaks are appears for the entire sample with the high intensity peak at 373 nm originated from the contribution of near band edge recombination from ZnO and low intensity at 573 nm was corresponding to ZnO defects.

Abstract: In recent years much attention has been devoted to natural antioxidant which has shown health benefits to human. Most researchers propose that two-thirds of thirds of the worlds plant species have a medicinal value and a great antioxidant potential. Polygonum minus or kesum is a traditional Malaysian plant used as flavoring agent and recommended for digestive disorders as well as stomach pain. The leaves are often eaten fresh as a vegetable (salad and ulam), especially among the Malay communities for preventive health care. There is a several researchers have been reported that P. minus contains a high level of antioxidant activities. Therefore, P. minus was seen to have a potential and interesting plant for antioxidant evaluation. The aim of this study is to represent previous studies that have been conducted on P. minus for antioxidant activities and also to suggest a method to enhanced antioxidant activities using nanotechnology.

Abstract: Conventional optimization method was conducted for the removal of lead from aqueous solution by used of intercalated malate layered double hydroxides. The effects of various parameters such as contact time, amount of adsorbent dosage and the pH of the lead solution are studied. The extent of lead ions removal increased with the increased in contact time and amount of malate-Mg-Al used however, the percentage removal was decreased with the increased in concentration and pH. The fundamentals of lead removal from aqueous solution by used of malate-Mg-Al can be explained by the formation of complexes between the malate and Pb²⁺ ions. The results from this study indicated that layered double hydroxide intercalated with malate could be used as potential adsorbent for the removal of lead ions from aqueous solution.

Abstract: ZnO in various nanostructures forms have been widely studied for the application such as in solar cells, light emitting diodes, UV sensors and so on. In this paper, we have successfully deposited ZnO nanotetrapods using thermal chemical vapour deposition (TCVD) technique on layer-by-layer ZnO seeded catalyst, with Zn powder and O₂ gas as source materials. We demonstrate that by using double furnace TCVD system, ZnO nanotetrapods can be deposited at lower temperature than the vapour temperature of the Zn powder. In this paper we report the effect of different deposition temperature (450 °C to 600 °C) on the surface morphologies, crystalline structure and optical properties of the ZnO nanotetrapods. FE-SEM micrographs show that the length of the nanotetrapods arms decreases with the increase of the deposition temperature. PL spectra show that the visible emission are very low compared to the UV emission which indicates that the ZnO tetrapod have very low intrinsic defect. The highest UV emission intensity is given by the sample deposited at 500 °C.

Abstract: Quantum dots (QDs) have a great potential to be applied as a biosensor to detect cancer cells because of their properties such as high photoluminescence, photo stability, narrow peak of luminescence, etc. However, cadmium sulphide (CdS) quantum dots are toxic and hydrophobic, making it impossible to be applied into biomaterials. A template is needed to make CdS QDs nontoxic and hydrophilic. The optical properties of these QDs are needed to be protected. To achieve this purpose, the template for CdS QDs has been designed by capping CdS QDs with apo-ferritin shells before aligning them onto cylindrical perpendicular PS-b-P2VP template, with the aim of locating CdS QDs appropriately in sequence. A host-guest system can be developed.

Abstract: In general, Iodine doping concentration can affect the conductivity of the CNTs and explicitly the efficiency of organic solar cells. Iodine is a p-type dopant and when doped into MWCNTs it form an electron acceptor in the form of (I₃)^- or (I₅)^-. Therefore, electron transfer from Iodine to MWCNTs can generate free hole carriers. This free hole carriers is then collected by the electrodes. However, the generated free carriers depend on the concentration Iodine being used. It can be seen that as the concentration of Iodine increase from undope, 40 mg, 60 mg and 1 g, the I-MWCNTs are well dispersed in the polymer matrix. The results obtained reveal that the films are smooth as the concentration of Iodine increased. This shows that the agglomerations of the CNTs are less when there is more Iodine being doped with the CNTs. It can also be observed that as the Iodine concentration increased the film thickness decreased. In this work, the possibility to get efficiency with thickness of less than 60 nm is proved and the obtained efficiency with thickness about 51 nm at 1 g Iodine doping has been recorded with 8.01 x 10^-4 %.

Abstract: This paper discussed the physical and electrical properties of annealed and non-annealed CNTs in nanocomposited MEH-PPV:CNTs. By comparing these two types of CNTs, it is proven that annealed CNTs showed improvement in both properties compared to the non-annealed CNTs. The main improvement related to the physical properties from one aspect, influence the electrical of the nanocomposited MEH-PPV:CNTs thin film. The non-annealed CNTs with diameter size 8-9 nm is lessen to 5-6 nm after annealing. The photo conductivity increased from 11.2 x 10^-3 S/m to 22.9 x 10^-3 S/m.

Abstract: In this work, zinc nitrate was used as starting materials while hexamethylenetetramine as stabilizier and deionized water as a solvent. Electrochemical etching method was employed to modify p-type silicon wafer surface in substrate preparation. ZnO nanostructures were simply deposited on substrate by sol-gel immersion method. Different molarities of precursor were prepared to study the effect of Zn²⁺ ion concentration in growth of ZnO nanostructures. Field Emission Scanning Electron Microscopic (FESEM) revealed that concentration of Zn²⁺ ion precursor influences the growth of ZnO nanostructures. ZnO nanoflower was formed in low molarity and becomes nanospherical composed by nanorods in high molarity. X-Ray diffraction (XRD) spectroscopy was employed to analyse the structural properties. The result was confirming the formation of hexagonal wurtzite of ZnO nanostructures. Besides, the growth of ZnO nanostructures was aligned to (002) towards higher molarity.

Abstract: Nickel (Ni) / indium tin oxide (ITO) nanostructures were deposited on glass and silicon (111) substrates by RF magnetron sputtering using a nickel target and ITO (In-Sn, 90%-10%) targets. The post-deposition annealing has been performed for Ni/ITO films in air and the effect of annealing temperature on the electrical, optical and structural properties on ITO films was studied. We found the appearance of (411) and (622) peaks in addition to (400) and (222) major peaks, which indicates an improvement of the film crystallinity at high annealing temperature of 650°C. The samples show higher transmittance of more than 90% at 460 nm after annealing. In addition, increasing the annealing temperatures also improve the film electrical properties. The resistivity decreases to 6.67×10^-6 Ωcm when annealed at 500°C as opposed to 6.75×10^-5 Ωcm in as-deposited film.

Abstract: In this study, the polymer nanocomposites was prepared by mixing the TiO₂ nanofiller into the polymer PMMA matrix using the sonication and solution casting technique. The PMMA/TiO₂ nanocomposite was prepared at different amount of TiO₂ in PMMA and was measured using FTIR, EDX and DMTA. The DMTA results show that the higher amount of TiO₂ in PMMA will contribute to the increase of the storage modulus of the nanocomposites. But, the too high amount of the filler will limit the properties of the nanocomposites. The FTIR and EDX analysis also are discussed in this paper.