Advanced Materials Research Vol. 1109

Abstract: In this study, CNTs samples were prepared by refluxing CNTs in nitric acid for 16 h at 110 °C and then followed by thermal treatment. The Co catalyst was synthesized by the strong electrostatic adsorption (SEA) method on the treated CNTs support. The Co/CNTs samples were then calcined at temperatures of 300, 350, 400, 450 °C. Samples were characterized by TEM and N₂ adsorption. The size of cobalt nanoparticles and the textural properties were influenced by the calcination temperature. The TEM results showed that cobalt nanoparticles were well dispersed on the treated CNTs support.

Abstract: Silicon dioxide film has been used as the gate dielectric material in MOS device technology for decades. The film is normally grown in a diffusion furnace using a dry thermal oxidation process. As the device is scaled down to nanometer dimensions, the SiO₂ film uniformity requirement is more stringent than ever. In this paper, the effect of furnace temperature and the flow rate of oxygen gas on wafer temperature distribution was investigated. The result was recorded by using the Infrared Thermometer with Dual Laser Targeting device (IRT5000). We have found that the uniformity of temperature distribution on the wafer is almost directly proportional to the O₂ flow rate for the entire furnace temperature range (900 - 1050°C). On the other hand, the effect of O₂ flow rate on wafer temperature distributions clearly shows two distinct regions; for furnace temperatures of less than 1000 °C, the higher the O₂ flow rate, the better the uniformity. For the furnace temperatures of more than 1000 °C, we did not observe any clear dependency of wafer temperature distribution on O₂ flow rate.

Abstract: This paper explains on how to fabricate TiO₂ on fluorine-doped tin oxide (FTO) substrate. The properties of FTO surface are electrically conductive, stable under atmosphere condition, chemically inert, mechanically hard, high temperature resistance and high tolerance to physical abrasion. This study focuses on growing titanium dioxide (TiO₂) on FTO substrate. TiO₂ is deposited onto FTO via hydrothermal method using hydrochloric acid (HCl), de-ionized water and titanium butoxide (TBOT) as precursor. The analyses are done on field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and spectrophotometer (UV-Vis). The TiO₂ grow on FTO substrate is showing uniformity and efficiency to be applied later in application of dye synthesis solar cells. Thus TiO₂ can absorb the light and spread the electrons faster to produce electricity.

Abstract: The structural and field emission properties of ZnO nanorod at different growth time by sol-gel method have been successfully prepared. FESEM results illustrated that dense ZnO nanorods with hexagonal wurtzite structure were vertically well-aligned and uniformly distributed on the substrate. X-ray diffraction pattern analysis shows that all the obtained ZnO nanorods can be indexed to the hexagonal ZnO wurtzite structure. Field emission measurement was conducted for ZnO nanorod growth at different time to study emission properties. The turn-on field value decreases while field enhancement value increases as longer growth time was applied which related to the increasing of aspect ratio of ZnO nanorod respectively.

Abstract: Synthesis of ZnO nanostructures has been demonstrated by using fresh extract of Citrus aurantifolia and zinc acetate dehydrate as a source material. Citrus aurantifolia extract was found to be a very effective agent for the reduction of Zn ions. The pH value of growth solution was set up to be 5 (acidic), 7 (neutral) and 9 (alkaline). The structural and optical properties of ZnO nanostructures have been investigated using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Photoluminescence (PL). By varying the pH, all samples exhibit rod-like structure however the length and diameter of the rod was varied. XRD demonstrated that all samples can be indexed to hexagonal wurzite structure with preferential orientation in (101) reflection plane. The room temperature PL spectrum was also analyzed which have shown a deep level emission which related to various intrinsic defects such as Zn interstitials and oxygen vacancies.

Abstract: Research innovation in finding new carbon sources for carbon nanostructures material production was intensively done lately. In this review, we present the production of carbon nanostructures such as carbon fibers, nanotubes, nanowhiskers, microspheres and porous carbon from several waste materials. The benefit of the use of waste materials such as waste cooking palm oil, chicken fat, waste natural oil, glycerol, printed circuit board, plastic wastes, waste engine oil, scrap tyre, heavy oil residue and deoiled asphalt is not only in the term of their environmentally friendly approach but also the economic value to reduce the high cost of carbon material production using common sources. On the other hand, these materials are easy access sources and can be alternative utilization to convert waste materials into high value nanomaterials.

Abstract: Nanotechnology is a most promising area that is increasing day by day and play a vital role in environments, biotechnological and biomedical fields. In recent years, the development of effective green chemistry methods for synthesis of various metal nanoparticles has become a main focus of researchers. They have investigated to find out a sustainable technique for production of well-characterized nanoparticles. A variety of chemical and physical methods have been exploited in the synthesis of silver nanoparticles (AgNPs) and these procedures remain expensive, high energy consumption and involve the use of hazardous chemicals. Therefore, there is an essential need to develop environmentally benign and sustainable procedures for synthesis of metallic nanoparticles. Increasing awareness of green chemistry and biological processes has need to develop a rapid, simple, cost-effective and eco-friendly methods. One of the most considered methods is production of nanosilver using plants and plant-derived materials which is the best candidates and suitable for large-scale biosynthesis of silver nanoparticles. Eco-friendly bio-organisms in plant extracts contain proteins, which act as both capping and reducing agents forming of stable and shape-controlled AgNPs. This review describes the recent advancements in the green synthesis of silver nanoparticles by using plants.

Abstract: The synthesis of nanoparticles is in the spotlight in modern nanotechnology. In recent years, the development of competent green chemistry methods for synthesis of metal nanoparticles (NPs) has become a main limelight of researchers. Biological synthesis of nanoparticles using plant extract is currently under exploitation. The first time in this paper we have reported the green synthesis of silver nanoparticles (AgNPs) by reduction of silver nitrate, using fruit extracts of Momordica charantia (bitter melon); commonly found plant in south East Asia. The reaction process for the synthesis of silver nanoparticles is simple, cost-effective, novel, rapid and eco-friendly route using fruit extract of M. charantia plant, which acted as a reducing and stabilizing agent simultaneously at room temperature. Formation of the nanosilver was confirmed by surface Plasmon spectra using UV-Vis spectrophotometer and absorbance peak at 440 nm. Different silver ion concentration and contact times were experimenting in the synthesis of silver nanoparticles. The prepared nanoparticles properties were characterized by UV-Vis.

Abstract: Graphene is a remarkable material with high electron mobility, good mechanical strength and almost transparent. In this paper, we review the available methods which are chemical vapour deposition, Hummers and electrochemical exfoliation method for the production of graphene. Among the extensive studies in the application of graphene, supercapacitor has gained much attention nowadays. Therefore, we also briefly review the application of graphene as electrodes for the supercapacitor devices.