Advanced Materials Research Vol. 1024

Abstract: A nanostructured hybrid consisting of a high-density and uniform assembly of gold nanoparticles (AuNPs) on multiwalled carbon nanotubes (MWCNTs) is always desired and demanded in various applications. However, a simple, cost effective and highly efficiency method is required in the fabrication of MWCNTs-AuNPs nanohybrids. This study introduces a method where MWCNTs were functionalizing with nitric acid (HNO₃) and sulphuric acid (H₂SO₄) in ratio of 1:3 v/v by using ultrasonication. These functionalized MWCNTs served as substrates for gold nanoparticle deposition. Later, it was pre-mixed with tri-sodium citrate (Na₃C₆H₅O₇.2H₂O), next it was reacted with nobel metal (AuNPs) via the addition of chloroauric acid (HAuCl₄) at various pH. When HAuCl₄ was added to the reaction system, Au³⁺ was directly reduced at the surface of the MWCNTs and gold nanoparticles were assembled along the MWCNTs. Fourier Transform Infrared (FTIR), Thermogravimetric Analysis (TGA), Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-ray (EDX) analysis and dispersion test were used to characterize the MWCNTs/AuNPs nanocomposites. The fully functionalized MWCNTs using acid oxidation at 4 hour using ultrasonication were used in synthesis of nanohybrids, and the optimum gold yield on MWCNTs obtained at pH 4. Compared to other methods, these procedures require low temperature without involving the need of any catalyst or surfactant which results in a simple and efficient method for fabrication of gold nanoparticles on carbon nanotubes.

Abstract: Synthesising zinc oxide nanoparticles to get certain specific characteristics to be applied in Enhanced oil recovery (EOR) is still challenging to date. In this work, zinc oxide (ZnO) nanoparticles were synthesised using the sol-gel method by dissolving zinc nitrate hexahydrate in nitric acid. The ZnO crystal and particles morphology and structure were determined using X-ray Diffractometer (XRD) and Field Emission Scanning Electron Microscope (FESEM). In this study, a microwave oven was used for annealing ZnO without insulating a sample in any casket. The results show that 30 and 40 minutes of annealing and stirring for 1 hour influenced the morphology and size of zinc oxide particles in nanoscale. These parameters could be tailored to generate a range of nanoparticle morphology (agglomerated nanoparticles in a corn-like morphology), a crystal size with the mean size of 70.5 and 74.9 nm and a main growth at the peak [10. EOR experiment were conducted by dispersing 0.10 wt% ZnO NPs in distilled water to form a ZnO nanofluid. Then the fluid was injected into the medium in the 3^rd stage of the oil recovery to present EOR stage. It was found that ZnO nanofluid has the ability to extract 8% of the original oil in place (OOIP).

Abstract: We demonstrate the vertically well-aligned zinc oxide (ZnO) nanowires synthesized on amorphous borosilicate glass (BSG) via simple chemical vapor deposition (CVD) process with a vapor trapping approach. During the process, zinc precursor was put inside a glass vial with the vial’s opening was directed towards the BSG substrate, which is being placed downstream from the gas flow and approximately 30-40 mm from the precursor. The BSG substrates were coated with Nichrome (NiCr) and gold (Au) coating prior to the synthesis process. Vertically aligned nanowires with a high aspect ratio was found to be deposited in total operating pressure of 20-25 bar with an Oxygen flow rate range of 5-10 sccm and argon flow rate range of 30-50 sccm. This vapor trapping approach using BSG substrates provided a good alternative towards controllable growth of ZnO NWs on any much cheaper amorphous substrates for future development of low cost energy-converter heat cell devices based on ZnO nanowires.

Abstract: Tungsten oxide (WO₃) nanorods were successfully grown at low temperature of 90 °C by seeded growth hydrothermal reaction. The effect of sodium chloride (NaCl) addition on nanorod aggregation was studied. The hydrothermal reaction was conducted at various reaction periods (16-24 h). Monoclinic WO₃ nanorods started to grow from the seeds after 18 h of hydrothermal reaction and more vertical nanarods were formed after 20 h of treatment. The addition of NaCl successfully reduced the aggregation of nanorods. Cyclic voltammetry (CV) was performed to measure the electrochromic properties of the WO₃ nanorods. WO₃ nanorods grown with NaCl showed faster intercalation and de-intercalation processes due to less nanorods aggregation.

Abstract: In this paper the TiO₂ nanoparticle for scattering layers were prepared using hydrolytic and non-hydrolytic sol gel route. The TiO₂ nanoparticles by hydrolytic sol gel were prepare by adding 5 ml of titanium (IV) isopropanol (TTIP) with 15 ml isopropanol. Then this TTIP mixture was added dropwise into 250 ml water with adjusted pH to 3 using nitric acids. For non-hydrolytic sol gel route 12 gram of acetylacetone, 12 gram of TTIP and 16 gram of ethanol anhydrous were mixed in a beaker under vigorous stirring. Then the prepared TiO₂ nanoparticles solutions were deposited onto TiO₂ mesoporous layer via spray pyrolysis and assemble into complete solar cell. From the XRD (X-ray diffraction) results show that the phase of TiO₂ nanoparticles formed by hydrolytic sol gel route was amorphous and for non-hydrolytic route the phase formed was mixture of anatase and rutile. The efficiency of the solar cell shows that scattering layer prepare by hydrolytic route give higher efficiency, 6.0 x 10^-5 %, as compare to scattering layer prepare by non-hydrolytic route, 4.9 x 10^-5 %.

Abstract: Anodisation of iron foil was done to produce anodic film with nanoporous structure. The effect of anodic voltage on the morphology of the anodic oxide formed was investigated. Anodic film formed on iron foil anodised at 10 V is rather compact no obvious pores. Pores can be detected on oxide anodised at 30 V despite not very uniform. For foil anodised at 50 V, 1.8 µm thick anodic layer which consisted of uniform circular pores is observed. This film was then annealed at 450°C for 3 h in air as to induce crystallinity. The annealed nanoporous film exhibits a light illuminated photocurrent of 0.45 mA in 1 M NaOH + H₂O₂ solution.

Abstract: Self-aligned ZrO₂ nanotube (ZNT) arrays were produced by anodization of Zr in aqueous sulphate/fluoride and ethylene glycol (EG)/fluoride electrolytes. The morphologies of the oxide produced were compared. It appears that the nanotubes formed in EG/fluoride are clearer showing smoother walls indicating better cell boundaries separation in this electrolyte. They are also longer with length > 10 µm after 1 hour of anodization. The x-ray diffraction pattern of the ZNTs revealed that ZNTs are cubic oxide.

Abstract: The feasibility of synthesizing TiO₂ nanoparticles using tetramethylammonium hydroxide (TMAOH) stabilized titanium tetraisopropoxide (TTIP) in natural rubber latex medium was investigated. The TiO₂ nanoparticles were separated using centrifugation and were characterized using SEM, TEM and XRD. It was found that the weight fraction of latex loaded in the reaction vessel affects the shape and size of the TiO₂ particles

Abstract: Crystalline ceria nanomaterials have been successfully synthesized through ionothermal treatment method. Morphology of the ceria nanoparticles are confirmed with scanning electron microscopy (SEM), transmission electron microscopy (TEM) with an average size of 6-30 nm and with the N₂ adsoprtion-desorption technique in the range of 46-62 m²g^-1 in the presence of ionic liquid as base on acetate anion, trifluoroacetate anion, dicyanamide anion as organic linker, cerium nitrate hexahydrate as precursor and ammonia. It was found that the cerium oxide synthesized by acetate anion based ionic liquid has cube shape morphology and gradually form belt shape as elevated the hydrothermal treatment temperature. Cerium oxide synthesized by trifluoroacetate anion based ionic liquid remains its cubic morphology even at elevated temperature. Whereas, cerium oxide synthesized by dicyanamide anion based ionic liquid, ceria particles agglomerate and form irregular structures. The synthesized ceria nanocrystals show better performance for the degradation of methylene blue.

Abstract: Micro powder injection moulding (μPIM) is one of the micro-moulding technology applied today in high-volume fabrication of metal and ceramic micro-components. The current study presents the micro powder injection moulding (µPIM) of 316L Stainless Steel nanopowder-polymer mixtures. 316L SS powders have been blended with a binder system which consists of Polyethylene Glycol (PEG), Polymethyl Methacrylate (PMMA) and Stearic Acid (SA). All the feedstock prepared shows homogeneity and pseudo-plastic behaviour which is suitable for μPIM process. The results showed that increase in nano powder content would improve the powder loading, injection and sintering temperature. Moreover, high physical and mechanical properties of the sintered specimen have been achieved under vacuum atmosphere. The above results indicate that application of nano powder has the potential to provide micro powder injection moulded parts with nearly full density, fine microstructure. The binder system is environment-friendly, has low viscosity-temperature and suitable to prepare feedstock for μPIM.