Abstract: In this study, nanosilver-graphene composites were successfully manufactured via the horizontal vapor phase growth (HVPG) technique. A quartz tube loaded with the starting material, equal masses silver (Ag) powder and multi-layer graphene (Ge), was evacuated to ~10-6 Torr, sealed, and then baked at 1200°C for 6 hours, with its orientation such that a horizontal temperature gradient was generated across the tube. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) analysis revealed variations in the structure and composition of the nanomaterials deposited on different regions of the tube, and the diameter of the nanomaterials was found to decrease with decreasing temperature.
Abstract: The Fe3O4/TiO2-Ni composites have been prepared by incorporating magnetic particles with doped photoactive titania using sono-coprecipitation and sol-gel methods. The composite was characterised by Fourier Transform infrared spectroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscopy with Energy Disperse X-Ray Spectroscopy (SEM-EDX), Vibrating Sample Magnetometry (VSM) and Specular Reflectance Ultraviolet-Visible light spectroscopy (SR-UV). The results indicated that the composite of Fe3O4/TiO2-Ni had been synthesised. XRD and FTIR results showed that the composite had a good anatase phase. SEM-EDX result confirmed the atomic percentage of element presence in the synthesised product and VSM result proved that the composite has an excellent magnetisation moment of 8.76 emus. SR-UV result suggested that the composite had a good bandgap property compared to that of synthesised undoped titania.
Abstract: Synthesis and characterization of Fe3O4/TiO2-Co as magnetic photocatalyst had been done. The research was started with the preparation of magnetite through co-precipitation and sonication system, followed by preparation of Co-doped TiO2 using sol-gel method and then mixed both of them with a ratio of Fe3O4:TiO2 1:3; 1:9; 1:15 (FT3, FT9, FT15) and ended by calcination. The product was characterised by using Fourier transform infrared spectrophotometer (FTIR), X-ray diffractometer (XRD), scanning electron microscope-energy dispersive X-ray spectrophotometer (SEM-EDX), UV-Specular reflectance spectrophotometer (SR-UV) and vibrating sample magnetometer (VSM). The resulting material showed a maximum value of band gap energy at 2.83 eV in FT3. The effect of Fe3O4:TiO2 ratio known can be affected the magnetic moment and showed the optimum result 2.0 emu/g in FT3. The magnetic character of Fe3O4/TiO2-Co also known can be affected by the magnetite crystalline size from the composites composition.
Abstract: Chitosan/polyvinyl-alcohol (Chitosan/PVA) based nanofibers were successfully produced using electrospinning machine and investigated their application as air filtration. Firstly, 2 wt% chitosan was dissolved to 1 wt% acetic acid followed by mixing with PVA solution to produce fiber mats or membrane. Secondly, the morphology and diameter of the electrospun fiber were analyzed by using a scanning electron microscopy (SEM), while the chemical compounds in the membrane were characterized using Fourier transform infrared spectroscopy (FTIR). It was found that the conductivity of solution increased by the concentration of chitosan. Meanwhile, the average diameter and percentage of porosity decreased due to the upsurge of the conductivity of the solution. The average diameter of PVA 13 wt% was and the percentage of porosity were 50.32%. The maximum condition of chitosan/PVA was obtained at 20/80 wt%, in line with the average of fiber diameters and the percentage of porosity were 25.32%. Physicochemical properties of chitosan/PVA solution, such as conductivity, morphology, and chemical absorption were investigated before and after the air filtration. The porosity percentage of PVA 13wt% after air filtration changed to 35.85% and the percentage of porosity of chitosan/PVA 20/80 became 25.32%. Remarkable absorption peaks of PVA 13wt% exhibited and - shifted after the air filtration test, it was indicating that functional groups had been reduced. The chemical absorption of chitosan/PVA 20/80 wt% showed at the the region then disappeared after the air filtration test.
Abstract: Synthesis of silver nanoparticles (AgNPs) by reduction of AgNO3 with o-hydroxybenzoic, p-hydroxybenzoic and o,p-dihydroxybenzoic acids as reducing agents was investigated. This research was conducted to determine the effect of the position and number of hydroxyl groups towards the size, shape and stability of the resulted AgNPs. Surface Plasmon Resonance (SPR) of AgNPs was characterized by UV/Vis spectrophotometer, the shape and size of AgNPs was determined by Transmission Electron Microscope (TEM). The results showed that the reducing agent that has substituents in the para position (p-hydroxybenzoic acid) has the higher reduction ability than the others. AgNPs were yielded by all types of reducing agents in alkaline system. Reducing agents which have greater number of substituents (o,p-dihydroxybenzoic acid) could produce AgNPs with smaller concentration of AgNO3 than the others. AgNPs that was produced by reducing agent having substituents on the para position (p-hydroxybenzoic acid) was more stable and smaller particle size, i.e. 34 ± 1.78 nm than reducing agent that has substituent on the ortho para positions (with particle size 45 + 3.67 nm) and ortho positions (with particle size 70 ± 4.96 nm).
Abstract: Gold nanoparticles (AuNPs) have been synthesised from adsorbed Au on hydrotalcite (Mg/Al HT-AA-Au) using SDS (sodium dodecyl sulfate) and sodium citrate as capping agent. Then, the nanoparticles were recovered into pure gold by centrifugation. It is shown that sodium citrate has better activity compared to SDS as the capping agent. The electronic spectra of the resulted AuNPs showed that the optimum pH, sodium citrate concentration and time of sonication were 5, 70 mM, and 2 h, respectively. The results showed that the average size of AuNPs was 32 nm at SPR 531 nm. By centrifugation at 13000 rpm for 8 min, gold dust of Au(0) can be obtained from the gold nanoparticles capped sodium citrate. Based on infrared spectra and XRD, it is proven that the gold dust still contains citric and Mg/Al HT.
Abstract: An overview of the RIKEN-RAL Muon Facility is reported. The RIKEN-RAL Muon Facility has been established at the Rutherford-Appleton Laboratory in the UK in 1992 and started to be in used for material science studies from 1994 by applying intense pulsed muon beams. More than 380 publications have been published in international journals and more than 100 domestic and international collaborations have been organized. As an example of those collaborative studies, a preliminary result of one recent experimental study on the magnetism in gold nano-cluster is reported. Additionally, a recent computational result on a local effect induced by an injected muon is reported in order to show how the presence of the muon leads to a local deformation of the crystal structure, thus changing the muon’s own position in finding the final stopping site self consistently.
Abstract: Vertically aligned nanorods ZnO have been deposited hydrothermally on the pre-coated ZnO seeded-glass substrates. Enhanced vertical alignment is achieved as a result of combined film post-treatments. Dipped-drawn and immersed-washing the as-synthesized ZnO films in water as well as quenching of the hydrothermal were proposed to hinder excessive deposition and engineer the growth of ZnO nanorods. The XRD patterns shows suppressed growth of ZnO crystallite along (101) with increased textural coefficients on (002), TC002, from 3.94 to 5.23. Dense vertically aligned bundles of ZnO nanorods may reach up to 0.75 μm length. Bandgap energy of the resulted ZnO nanorod thin films were ranging from 3.69 to 3.79 eV, wider than those of bulk ZnO. Hydrothermal technique with simple post-treatments of immersed-washing and hydrothermal quenching has offered robust and efficient method to prepare vertically-aligned 1-D ZnO nanorods potential as photoanodes for dye-sensitized solar cells.
Abstract: We present the thermoelectric properties of individual PbTe (lead telluride) nanowire (NW) grown by a stress induced method. Temperature-dependent thermoelectric power and electrical conductivity in PbTe NW with diameter 125 nm were investigated in temperature ranging of 300−400 K. The PbTe NW was found to have a Seebeck coeficient S and electrical conductivity σ of −121 μV K−1 and 138 S cm−1 at 300 K, respectively. The calculated power factor (PF) of PbTe NW (d = 125 nm) demonstrate an enhancement, wich is higher than that have been previously reported in PbTe NWs. Such an enhanced thermoelectric performance can in part be attributed to the size effect of nanowires.