Browsing by Subject "Surface area"

Now showing 1 - 5 of 5

Open Access
Effect of area on color harmony in simulated interiors
(Society for Imaging Science & Technology, 2017) Odabaşıoğlu, Seden; Olguntürk, Nilgün
Open Access
Mesoporous metallic rhodium nanoparticles
(Nature Publishing Group, 2017) Jiang B.; Li C.; Dag, Ö.; Abe, H.; Takei, T.; Imai, T.; Hossain, M. S. A.; Islam, M. T.; Wood, K.; Henzie, J.; Yamauchi, Y.
Mesoporous noble metals are an emerging class of cutting-edge nanostructured catalysts due to their abundant exposed active sites and highly accessible surfaces. Although various noble metal (e.g. Pt, Pd and Au) structures have been synthesized by hard- and soft-templating methods, mesoporous rhodium (Rh) nanoparticles have never been generated via chemical reduction, in part due to the relatively high surface energy of rhodium (Rh) metal. Here we describe a simple, scalable route to generate mesoporous Rh by chemical reduction on polymeric micelle templates [poly(ethylene oxide)-b-poly(methyl methacrylate) (PEO-b-PMMA)]. The mesoporous Rh nanoparticles exhibited a ∼1/42.6 times enhancement for the electrocatalytic oxidation of methanol compared to commercially available Rh catalyst. Surprisingly, the high surface area mesoporous structure of the Rh catalyst was thermally stable up to 400 °C. The combination of high surface area and thermal stability also enables superior catalytic activity for the remediation of nitric oxide (NO) in lean-burn exhaust containing high concentrations of O 2.
Open Access
Molecular entrapment of volatile organic compounds (VOCs) by electrospun cyclodextrin nanofibers
(Elsevier, 2016-02) Celebioglu A.; Sen, H. S.; Durgun, Engin; Uyar, Tamer
In this paper, we reported the molecular entrapment performance of hydroxypropyl-beta-cyclodextrin (HPβCD) and hydroxypropyl-gamma-cyclodextrin (HPγCD) electrospun nanofibers (NF) for two common volatile organic compounds (VOCs); aniline and benzene. The encapsulation efficiency of CD samples were investigated depending on the various factors such as; CD form (NF and powder), electrospinning solvent (DMF and water), CD (HPβCD and HPγCD) and VOCs (aniline and benzene) types. BET analysis indicated that, electrospun CD NF have higher surface area compared to their powder form. In addition DMA measurement provided information about the mechanical properties of CD NF. The encapsulation capability of CD NF and CD powder was investigated by 1H-NMR and HPLC techniques. The observed results suggested that, CD NF can entrap higher amount of VOCs from surroundings compared to their powder forms. Besides, molecular entrapment efficiency of CD NF also depends on CD, solvent and VOCs types. The inclusion complexation between CD and VOCs was determined by using TGA technique, from the higher decomposition temperature of VOCs. Finally, our results were fortified by the modeling studies which indicated the complexation efficiency variations between CD and VOC types. Here, the inclusion complexation ability of CD molecules was combined with very high surface area and versatile features of CD NF. So these findings revealed that, electrospun CD NF can serve as useful filtering material for air filtration purposes due to their molecular entrapment capability of VOCs.
Open Access
Role of organic and inorganic additives on the assembly of CTAB-P123 and the morphology of mesoporous silica particles
(2009) Poyraz, A. S.; Dag, Ö.
Mesoporous silica particles with various morphologies and structures have been synthesized by controlling the solubility, micellization, and assembly of a charged surfactant (cethyltrimethylammonium bromide, CTAB) and a pluronic (PEO20PPO70PEO20, P123) couple using an organic (benzene) or an inorganic (SO4 2-, NO3 -, or Cl-) additive. The effect of CTAB, with or without one of the Hofmeister ions or benzene in various concentrations, on the morphology, pore-size, pore-structure and the nature of the silica particles has been investigated. Increasing the lyotropic anion (SO4 2-) or benzene concentration of the synthesis media creates wormlike particles with enlarged pores and reduced wall thickness. However, the hydrotropic anion (NO3 -) influenced the solubility of the charged surfactant and increased the CTAB concentration in the CTAB-P123 micelles, and as a result, in the mesoporous silica particles. The surface area, unit cell, and pore size of the silica particles are diminished by increasing the nitrate ion centration. The effects of the Cl- ion are between the SO4 2- and NO3 -ions. It influenced the P123 at low and CTAB at high concentrations. At low CTAB/ P123 mol ratios, the Cl- ion affects mainly the P123, but at high CTAB/P123 it affects both the CTAB and P123. By carefully adjusting these ingredients (CTAB, SO4 2-, Cl-, NO3 - and benzene), not only the morphology of the particles, but also the pore-size and pore-structure of the mesoporous silica particles could be adjusted. The investigations were carried out by preparing a series of powder samples and, by varying the CTAB/P123 mol ratio (between 3.0 and 6.0) and the concentration of the organic (0.17 to 0.90 M) or inorganic (at 0.25, 0.50, or 1.00 M) additive in the synthesis media. The powder samples were analyzed using microscopy (SEM, TEM, and POM), diffraction (PXRD), and spectroscopy (FTIR, Raman, UV-vis, and EDS) techniques toward above goals. © 2009 American Chemical Society.
Open Access
Self-assembled one-dimensional soft nanostructures
(Royal Society of Chemistry, 2010) Toksoz, S.; Acar, H.; Güler, Mustafa O.
The self-assembly process is a bottom-up approach and is the spontaneous aggregation of many different subunits into well-defined functional structures with varying properties. Self-assembly is an attractive method to develop one-dimensional nanostructures and is controlled by many factors including temperature, pH and electrolyte addition. Novel self-assembled one-dimensional nanostructures are finding applications in regenerative medicine and electronics as well as in fabrication of nanoscale electronic, mechanic, magnetic, optical, and combinatorial devices. Their utility comes from their high ratio of surface area to volume, and their quantum-confinement effects. This paper reviews one-dimensional self-assembled organic nanostructures classified according to the noncovalent forces acting on their formation.