Key Engineering Materials Vols. 675-676

Abstract: In this study, Iron nanoparticles (FeNPs) were synthesized by green chemical method. A reducing and stabilizing agent from plant were used instead of toxic chemical reagent. It was observed that FeNPs was obtained at room temperature (25-35 °C) using bioreducing agent without voltammetric method. The optimum condition for FeNPs synthesis was studied. The nanoparticles have been preliminary characterized by UV-vis spectrophotometry.

Abstract: Graphene is of apply in wide range of research fields and may even motivate researchers to develop a new hybrid material with experience properties. In this works, growth of zinc oxide (ZnO) nanoparticles on reduced graphene oxide (rGO) using chemical reduction method was reported. Particle size, morphology and crystal structure of ZnO/rGO were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) technique, respectively. Sensing application of ZnO/rGO was discovered. ZnO/rGO was used as an active material for sensing acetone diluted in water. The preliminary results showed that the sensitivity of acetone sensor.

Abstract: ZnO nanorods were grown on magnetron sputtered ultra-thin ZnO seed layers through a hydrothermal method. Before ZnO nanorods growth, the ultra-thin ZnO seed layer has been annealed at temperatures ranging from 100 to 400°C in air. The influence of annealing treatment on the crystalline structure of the ultra-thin ZnO seed layers has been investigated by X-ray diffraction (XRD). The size and density of final prepared ZnO nanorods were investigated by field-emission scanning electron microscopy (FE-SEM). It was found that the length and the aspect ratio of the ZnOnanorods can be readily tuned by control of the ZnO ultra-thin seeds layer which results from the annealing treatment process.

Abstract: In this study, we fabricated the zinc oxide (ZnO) nanorods arrays by hydrothermal technique on indium doped tin oxide (ITO) substrate with different concentration of the precursor with zinc nitrate and hexamethyleneteramine (HMTA) in distilled water. Structure, morphology and optical properties of ZnOnanorods on ITO substrate were characterized by x-ray diffractometer, field-emission scanning electron microscope and spectrophotometer, respectively. The ZnO nanorod arrays showing preferentially oriented in the (001) direction and with a wurtzite structure. The scanning electron microscopy results showed that the hexagonal shape ZnO nanorods. It was found that the diameter, length and density of the ZnO nanorods arrays were strongly influenced by the precursor concentration.

Abstract: In this work, zinc oxide (ZnO) nanoparticles were synthesized by simple chemical precipitation method in the present of zinc nitrate as zinc precursor and sodium hydroxide as hydroxide precursor. The vitamin C was used as modifier media to modify the structural properties of ZnO nanoparticles. The microstructures of ZnO nanoparticles were characterized by field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). Selected area electron diffraction (SAED) patterns showed that polycrystalline hexagonal phase of ZnO. The defects and impurity contents in nanoparticles were investigated by Fourier transform infrared (FT-IR) spectroscopy. The results show few carboxylate and hydroxyl impurities for larger particles when addition modifier increases. Surface areas of nanoparticles were measured by Brunauer Emmett Teller (BET) method. In addition, the results exhibited the dramatically change in structural properties of ZnO nanoparticles due to the effect of vitamin C.

Abstract: Silver nanorods, prepared on Si substrates by sputtering deposition with the technique glancing-angle deposition (GLAD), were used as surface-enhanced Raman scattering (SERS) substrates. The prepared samples were categorized into two groups based on sealing conditions after the nanorod fabrications. The non-sealed SERS substrates were prepared by purging in the vacuum chamber with argon, oxygen, and ambient air. The sealed SERS substrates were enveloped with several types of packages, i.e., petri dishes, plastic bags, and foils, where they were all handled in a controlled glove box. The samples were characterized by field-emission scanning electron microscopy (FESEM) for the physical morphologies. The samples were further investigated by Raman spectroscopy for Raman spectra of blank substrates of each condition. The results showed that, in case of the non-sealed category, the SERS substrates purged under the argon gas was best optimized to prevent ambient contamination during prolonged period of time. In the case of the sealed category by different packages, the SERS substrates demonstrated the enhancement of the Raman-shift spectra with very small unwanted peaks, and in addition the extended lifetime.

Abstract: nanosized manganese oxide particles are attracted considerable interest in many industry areas especially in energy storage device applications because of their unique properties. For industry large scale synthesis, it needs a simple and low energy technique for scaling up production process. In this work, nanosized manganese oxide particles were prepared via a solid-state reaction route at room temperature. The products were characterized by field emission scanning electron microscopy (FE-SEM) coupled with energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction infrared spectroscopy (XRD), and raman spectroscopy. The results show that the sizes of particles were smaller than 50 nm with narrow size distribution and high yield were obtained. In addition, this technique may be applicable to industry production of nanosized manganese oxide or nanosized manganese oxide composite.

Abstract: Well-defined Sb-doped tin oxide (ATO) nanofibers were synthesized by electrospinning technique. Polyvinylpyrrolidone (PVP), SnCl₄·5H₂O and SbCl₃ were chosen as suitable precursors for preparing ATO nanofibers. All of precursors were homogeneously dissolved with the mixture solvent of dimethylformamide (DMF) and absolute ethanol. Electrospinning process was carried out at applied voltage of 10 kV and distance between needle tip to aluminium foil collector was fixed at 10 cm. The injection rate of precursor solution was controlled at 0.5 ml/hr. The as-spun nanofibers were calcined at 600°C with heating rate of 5 °C/min in order to remove the PVP template and improve the crystallinity of ATO structure. Effect of Sb doping concentration on their crystal structure was investigated. The morphology and crystal structure of the electrospun fibers were analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD). In this work, the obtained ATO nanofibers had average range diameter from 150 to 350 nm with rough surface. Sb doping concentration in ATO nanofibers plays a key role on their network morphology. The excellent doping concentration of Sb that offered the continuous fibrous and porous ATO nanofibers was 7%.

Abstract: Many researchers have currently interested in using Fe₃O₄ magnetic nanoparticles (MNPs) impregnated onto agricultural wastes for removal of heavy metal ions in wastewater treatment process. In this work, the MNPs-pomelo peel powder (MNPs-PP) composites were developed and their adsorption capacities of heavy metal ions were studied as well. The MNPs-PP samples were synthesized by co-precipitation method in different ratios; 2:1, 2:2, 2:4, 2:5, and 2:6 (by weight). The results showed that the as-synthesized MNPs were mainly spherical shape with an average particle size of approximately 12.7 ± 0.6 nm. Then, the MNPs, PP and MNPs-PP in different ratios were used as adsorbents for adsorption of 25 ppm Cu²⁺ in aqueous solution. The pH and temperature of solution were kept constant at 5 and 30 °C, respectively. From the experiment, it was found that the adsorption capacities decreased in the following order: PP > MNPs-PP (2:6) > MNPs-PP (2:5) > MNPs-PP (2:4) > MNPs-PP (2:2) > MNPs-PP (2:1) > MNPs. It indicated that the adsorption capacity of as-synthesized MNPs-PP is significantly higher than that of sole MNPs. Furthermore, the adsorption capacities of MNPs-PP increased with increasing the weight ratio of PP. The MNPs-PP developed herein has demonstrated not only high adsorption efficiency but also have shown additional benefits such as ease to synthesis, cost-effectiveness, environmental-friendliness, and ease to separate from treated water by an external magnet.

Abstract: Magnesium oxide (MgO) nanostructures were synthesized by microwave-assisted thermal oxidation at various amount of activated carbon additive. The MgO nanostructures were characterized by scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffractrometry (XRD) and UV-Visible spectroscopy, respectivly. It was observed that, the obtained MgO have nanocube shape. The MgO nanostructures were applied as a blocking layer in ZnO dye-sensitized solar cells (DSSC). The photovoltage, photocurrent, and power conversion efficiency characteristics of DSSCs were measured under illumination of simulated sunlight obtained from a solar simulator with the radiant power of 100 mW/cm². The DSSCs with MgO layer exhibited higher current density, open circuit voltage and photoconversion efficiency than those without MgO layer The optimum power conversion efficiency (PCE) was 2.49 % with short circuit current (J_sc) of 6.61 mA/cm², the open circuit voltage (V_oc) of 0.66 V and the fill factor (FF) of 0.59, respectively.