Search

• The Fe-TiO 2 nanostructure enhances transesterification reaction. • FE-TiO 2 nanocatalyst produces biodiesel with low fatty acid. • Biodisel yield can be up to 31 %. The impact of Fe doped TiO 2 nanocatalyst on the heterogeneous catalytic transesterification reaction of coconut oil into biodiesel has been investigated. The nanocatalyst was prepared by sol-gel method using titanium isopropoxide as TiO 2 precursor and Fe(NO 3) 3 as iron (Fe) source. Several conditions of Fe-TiO 2 were synthesized, each with Fe concentration of 0.5 %, 1 %, and 1.5 %, and calcined at 500 °C. The nanocatalyst's physical and chemical characteristics including phase crystallinity and morphology were examined. We found that the biodiesel conversion efficiency increases with the increasing of Fe content in the Fe-TiO 2 nanocatalyst and optimum at the Fe concentration of 1.5 % (w/w). The optimal Fe-TiO 2 nanocatalyst could yield biodiesel output as high as 30.8 %, under at a relatively low temperature of 60 °C. Furthermore, the presence of the nanocatalyst effectively reduced the free fatty acid content in the biodiesel product by 1.43 %. Moreover, the acidity of the produced biodiesel was exceptionally low, at 0.02 %, primarily attributed to lauric acid. These exceptional performances are believed to be attributed to the enhanced surface chemistry properties of the Fe-TiO 2 nanocatalyst. The Fe-TiO 2 system is expected to find extensive application in the cost-effective production of biodiesel. The Fe-TiO 2 nanocatalyst promotes efficient transesterification of coconut oil for biodiesel production. [Display omitted] [ABSTRACT FROM AUTHOR]

Anisotropic nanostructures, such as nanosheets, nanorods, etc., in many cases, generate superior physicochemical properties over a highly symmetric structure counterpart. Here, we present a straightforward method to grow vertically oriented ZnO nanosheet directly on fluorine-tin oxide substrate using a microwave-assisted quasi-hydrothermal method. We also found that the Ag nanoparticles (AgNPs) loading on the surface can effectively modify their optical properties, the potential for upgrading its performance in the existing applications. Due to the simplicity of the technique, AgNPs-loaded standing ZnO nanosheet should find potential application in solar cells, sensing and photocatalysis. [ABSTRACT FROM AUTHOR]

Charge collection, transport and the recombination, which can be described by a capacitance of the device, in a dye-sensitized solar cell determine the performance of the device. High capacitance renders efficient charge collection, transport and suppressing the recombination in the device. Here, we report the existence of quantum capacitance or electrochemical capacitance like phenomenon effect in the improvement of the performance of the DSSC device in the presence of Au nanoparticles. By comparing the photovoltaic performances of plasmonic DSSC (ITO|TiO 2 :Au:dye(N719)|Iodolyte|Pt) with normal DSSC (without gold nanoparticles), it is found that the power conversion efficiency is enhanced by 15.23%, namely from 4.07 to 4.69%, when the Au nanoparticles presence in the device. Electrochemical impedance and optical absorption and X-ray photoelectron spectroscopy analysis suggested that the improvement of the device performance is related to the enhancement of the optical activity of the TiO 2 nanostructure via plasmonic effect and defect or oxygen vacancy density modification and the enhancement of carrier transport due to existence of the quantum capacitance effect in the device. The mechanism of the performance enhancement will be discussed in detail. [ABSTRACT FROM AUTHOR]

Abstract: A simple approach to control the attachment of gold nanoparticles (AuNPs) onto the indium tin oxide (ITO) surfaces is reported. Adjusting the concentration of trisodium citrate in the Au colloid solution for the seeding process from 1 to 50mM in the seed-mediated growth method, the dramatic changes in the SEM images and actual color were observed indicating the changes in nanostructures of AuNPs formed on the ITO surfaces. Whereas the attachment of smaller AuNPs with higher density were observed when 25mM citrate ions were added in the seed solution, larger AuNPs were observed to attach at 50mM. On the basis of this difference and the surface SEM images observed just after seeding, the roles of citrate ions were discussed. Consequently, it was inferred that the citrate ions affected the growth process as well as the seeding process. The repulsive power expected from the increased negative charges of citrate ions were not significant, but rather the dense attachment was promoted as the peculiar effect of citrate ions. Such control of the AuNPs attachment on ITO would be practically effective because the dense attachment can be performed by just changing the composition of the seed solution. [Copyright &y& Elsevier]

Abstract: An effective approach to attach gold nanoparticles (AuNPs) directly on indium tin oxide (ITO) surface with higher density is reported. The attachment was carried out using a cast seed-mediated growth method, which was revised from our previous seed-mediated growth approach. The cast seeding with three-cycles of the drop of the seed solution containing Au nano-seed particles and the evaporation at 30°C followed by the treatment in the growth solution containing HAuCl4, cetyltrimethylammonium bromide (CTAB) and ascorbic acid was found to be suitable to prepare the AuNPs attached ITO surfaces having higher density and narrower size distribution. The 10-cycles cast seeding formed the connected or networked nanostructures of AuNPs, though the optical properties were different from those of the dispersed AuNP-attached ITO. The present cast seeding approach provides a facile and useful strategy to attach AuNPs on the surface without the use of certain organic binder molecules. [Copyright &y& Elsevier]

Abstract Charge-transfer and photoactivity at an interface of a photoactive materials, such as ZnO, is critically influence the performance of dye-sensitized solar cell (DSSCs). The performance of DSSCs utilizing Au decorated ZnO nanorod photoanode with Au nanoparticles grown at seven different growth times from 0.12 up to 6 min were studied. It was found that the charge transfer characteristic of DSSCs devices utilizing Au decorated ZnO nanorods increased with the increasing of Au nanoparticles size and density and optimum at Au nanoparticles size of ca. 15 nm and density of approximately 4–10 nanoparticles/nanorods. At this condition, the charge transfer resistance as low as 7.4 Ω was recorded. This is equivalent to power conversion efficiency of 1.11%. The charge transfer resistance gradually declined when the growth time further elongated. The efficient charge transfer can be associated to the excellent catalytic properties of Au nanoparticles on ZnO nanorods. This also improves its carrier transport in the device as judged from significantly low dark current properties. The improvement of light absorption can also be considered to improve the performance, attributed to the surface plasmon resonance (SPR) effect of the gold nanoparticles. The preparation of Au nanoparticles decorated ZnO nanorods and the mechanism of charge transfer characteristics will be discussed. Highlights • Charge transfer activity enhances in ZnO nanorods photoanode upon being decorated by the Au nanoparticles. • The carrier dynamic increases with the increasing of the nanoparticles density on the surface of ZnO nanorods. • Photovoltaic performance improves due to combinative effect of enhanced carrier dynamic and charge transfer activity. [ABSTRACT FROM AUTHOR]

In this work, samarium (Sm) supported on tin oxide–titanium oxide (SnO 2 /TiO 2 ) nanoparticles (Sm/SnO 2 –TiO 2 ) were synthesized by sol–gel, ultrasonic and hydrothermal methods; and the optical and catalytic properties of Sm/SnO 2 –TiO 2 nanoparticles was observed. Effect of synthetic methods on nanoparticles size and percentage composition of anatase and rutile phase in TiO 2 was evaluated. The Sm/SnO 2 –TiO 2 nanoparticles were characterized by Transmission Electron Microscopy, Scanning Electron Microscopy, Energy Dispersive X-ray spectroscopy, Powder X-ray Diffraction, Thermogravimetric Analysis and Fourier Transmission Infrared Spectroscopy. However, UV–Vis and solid phase spectroscopy were used to determine the catalytic efficiency and optical band gap, respectively. It was found out that nanoparticles synthesized by sol–gel and hydrothermal method have small optical band gap as compare to nanoparticles synthesized by ultrasonic method and ultimately showed more catalytic activity toward degradation of dye due to red shift in the optical band gap (shifting of wavelength to visible region). A direct relationship between particle size and optical band gap was investigated. It was observed that Sm reduced the optical band gap and increased catalytic efficiency when supported on SnO 2 /TiO 2 . [ABSTRACT FROM AUTHOR]

Abstract: The effect of alkyl polyglucoside (APG) surfactant on the electrodeposition Co–Ni–Cu alloys nanoparticles has been investigated. In a typical electrodeposition experiment, it was found that as prepared Co–Ni–Cu alloys nanoparticles characteristics, such as size homogeneity, density, dispersion on the electrode substrate and the chemicals composition, depended strongly on the concentration of APG used in the reaction as well as the applied deposition potential. For the case of chemicals composition, low APG concentration (below CMC) was found to be effective for the preparation of excellent composition of the nanoalloys. Meanwhile, for the case of size homogeneity, density, and dispersion on the surface, high APG concentration (above CMC) and high deposition potential were preferred. It was also found that, at concentration above the CMC, the APG surfactant showed a metals ions deposition inhibition characteristic that caused increasing in the electrodeposition overpotential of the entire metals ions, namely cobalt, nickel and copper. As the result the copper was found to place a high percentage in the nanoalloys deposits. Owing to its simple procedure in controlling the composition and the nanoalloys growth characteristic, present approach should find a potential application in preparing Co–Ni–Cu magnetic nanoparticles for used in currently existing applications. [Copyright &y& Elsevier]

• Eco-synthesis of Au doped TiO 2 /ITO CNPs was prepared via a liquid chemical reaction and mediation technique into a glass tube. • The unique crystal of Au-TiO 2 /ITO CNPs has driven the shining effect for plasmonic photocatalyst under visible light. • Plasmonic photocatalyst performance for modelling the degradation process under visible light irradiation against MO organic compound. The unique of coral-needle nanoparticles (CNPs) were prepared via a liquid chemical reaction and mediation technique to develop the eco-synthesis of Au-TiO 2. Based on this study, Au-TiO 2 has a high-performance compared with TiO 2 for the degradation of methyl orange (MO) organic compound under visible light irradiation which evidenced by the optical properties of each product. Au-TiO 2 CNPs has high-response of absorption activity in the visible light area in a range of 555–600 nm, whereas the activity of TiO 2 remains a low-level absorption. Also, the successful decoration of Au exhibits that the Au-TiO 2 CNPs has gives the sparkling morphologically effect and dramatically for plasmonic photocatalytic with the CNPs structure. We also testing photocatalytic activity that the increase of repetition the Au coated onto TiO 2 is rationalized for high-sensitivity degradation of MO organic compound under visible light irradiation with % degradation of ∼36 % for 120 min. This study can provide useful new information about the design for the Au-TiO 2 plasmonic photocatalysts for solar-to-chemical transformations. [ABSTRACT FROM AUTHOR]