Advanced Materials Research Vol. 364

Abstract: This study describes the formation of spherical gold nanoparticles (AuNPs) using a simple seeded-growth technique. The size and surface morphology of AuNPs were investigated using transmission electron microscopy (TEM) and UV-Vis spectrophotometer was used to determine the wavelength and absorption of AuNPs. In the seed stage, the effect of trisodium citrate volume was studied. The size of AuNPs at seed stage was varied from 15 to 40 nm with decreasing volume of trisodium citrate. In the growth stage, the effects of seed solution volume and concentration of hydroxylamine were studied. The size of AuNPs produced became larger when the amount of seed solution was reduced. This approach was beneficial to produce AuNPs with the size range from 15 to 150 nm. The increase of hydroxylamine concentration increased the size of AuNPs. However, after the concentration of hydroxylamine reached supersaturation condition (3 M NH₂OH.HCl), the AuNPs formed in a bulk and clusters. Selected sizes of AuNPs were then conjugated to antibody and proved by testing on the immunoassay test strip. The observation using naked eyes for the appearance of red lines on the immunoassay test strip showed that AuNPs were successfully conjugated to antibody and specifically bound to the antigen drawn on the strip assay by tested with positive and negative serum of the disease.

Abstract: Zinc oxide (ZnO) nanoparticles with spherical morphologies were successfully produced via precipitation of Zn and I₂ with DEA was employed as a chelating agent. The products were further heat treated at four different calcinations temperature commences from 250 °C to 1150 °C. Studies on ZnO structural, morphologies and optical characteristic with respect to calcinations temperatures were conducted using XRD, TEM and PL spectroscopy respectively. The XRD spectra reveal hexagonal wurtzite signature along with preferred orientation growth in (101) plane. Particles size of ~ 60 nm and strong blue-violet emission peak of 417 nm (3.0 eV) has been observed for ZnO calcined at 850 ^ᵒC. Results reveal a close relationship between the calcinations temperature and ZnO microstructure whereas, its luminescence behaviour showing a strong depending on ZnO microstructure.

Abstract: Nanowires V₂O₅ was synthesized by sonochemical pretreatment using NaNO₃ in several durations (30 – 120 min). XRD patterns of the sonicated V₂O₅ gave similar structure with a pure V₂O₅ phase without the presence of other diffraction peaks which attributed to any different phases. Prolonged the duration of sonication also has led to an increased in the intensity peaks of the diffraction peaks_, which indicate relatively high crystallinity. TEM micrographs show that after 120 min pretreatment, nanowires V₂O₅ with much smaller diameter (~10 – 15 nm) was produced and has explained the main factor for the decrement in the crystallite sizes of the sonicated V₂O₅ found in the XRD data. The TEM micrographs also show that the sonicated V₂O₅ formed bulk of nanowires V₂O₅ when the duration of sonication was prolonged. The high energy of ultrasonic pretreatment induced the self-assembled phenomenon which caused the nanowires V₂O₅ to agglomerate and formed bundle.

Abstract: Methane reforming is the most feasible techniques to produce hydrogen for commercial usage. Hence, dry reforming is the environment friendly method that uses green house gases such as CO₂ and methane to produce fuel gas. Catalysts play a vital role in methane conversion by enhancing the reforming process. In this study Ni/γ-Al₂O₃ was selected as based catalyst and CeO₂ and Fe₂O₃ dopants were added to investigate their effect on catalytic activity in dry reforming. The catalysts synthesized through wet impregnation method and characterized by using XRD, TEM and SEM-EDX. The catalytic tests were carried out using temperature programmed reaction (TPRn) and the products were detected by using an online mass spectrometer. The results revealed that these dopants significantly affect the catalytic activity and selectivity of the catalyst during reaction. Hence, Fe₂O₃ doped catalyst shows higher hydrogen production with stable catalytic activity.

Abstract: CeO₂-SiO₂ (C-S) Binary Oxides Were Prepared by Deposition Precipitation as Modified Support. Nanoparticle Nickel Catalysts (5 Wt.%), Supported on SiO₂ and CeO₂-SiO₂ Were Prepared by Impregnation. Catalysts Were Identified by Several Characterizations (XRD, BET, TPR, TPD and TEM). the Analyses Showed that Nanoparticle Ni Supported on CeO₂-SiO₂ Catalysts Gave Better Properties in Reducibility, Basicity, Ni Metal Dispersion and Size Compared to the Nickel Catalysts Supported on the Single Oxide SiO₂. the Catalytic Test of Dry Reforming of CH₄ with CO₂ (DRMC) Reaction Was Conducted Using Temperature Programmed Reaction (TPRn) Technique which Connected to an Online Mass Spectrometer. the Catalytic Test Showed that Ceria (CeO₂) Loading Influenced the Activity, Mainly the Hydrogen Production. Ni Catalyst with 9 Wt.% of Ceria Exhibited the Highest Hydrogen Production and it Was Suggested to Be the Optimum Value of Ceria Loading. in Addition, the Lower Amount of Carbon Was Observed on the Ni/9C-S Catalyst. this Revealed that the Addition of an Appropriate Amount of Ceria Increased the Hydrogen Production and Reduced the Carbon Formation.