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Abstract: Adsorption and electrochemical reduction of pyrantel pamoate are studied in Britton Robinson buffer medium at hanging mercury drop electrode (HMDE) by Adsorptive Stripping Voltammetric technique. The peak current shows a linear dependence with the drug concentration over the range 250ngmL−1 to 64μgmL−1. Applicability to assay the drug in urine samples is illustrated in the concentration range 5–20μgmL−1. [ABSTRACT FROM AUTHOR]

Abstract: Hollow Pd–Fe nanospheres were fabricated through a vesicle-assisted chemical reduction method. With the characterization of X-ray diffraction, selected area electron diffraction, X-ray photoelectron spectroscopy, scanning electron micrography, transmission electron micrography, and N2 physisorption experiment, the resulting Pd–Fe material was identified to be hollow spherical with mesoporous shell. During aqueous Sonogashira-, Heck-, and Ullmann-type coupling reactions of aryl halide, the as-prepared hollow Pd–Fe nanospheres exhibited much higher activity than the dense counterpart nanoparticles. The enhanced reactivity was attributed to both the hollow chamber structure and the promotional effect of Fe-dopants, which provided more Pd active sites for the reactants. Moreover, this hollow material displayed other advantages such as low-cost, recyclability and easy experimental handling. [Copyright &y& Elsevier]

Abstract: Nano-gold dispersed water based nanofluid has been prepared following the chemical reduction method. Crystallite size, particle size/shape/morphology, and purity of the nanoparticles have been characterized using X-ray diffraction, scanning and transmission electron microscopy and energy dispersion spectroscopy, respectively. The degree of thermal conductivity enhancement of the nanofluid (with respect to the base fluid) as a function of concentration and size of gold nanoparticle has been determined using the transient hot-wire technique. The degree of enhancement increases with increase in concentration and decrease in size of nanoparticles. The maximum enhancement recorded is ∼48% at 0.00026vol.% concentration and 21nm average particle size. [Copyright &y& Elsevier]

Abstract: The present work explored the effect of MnO x modification on the activity and adsorption of CuO/Ce0.67Zr0.33O2 catalyst for NO reduction by CO. XRD, Raman, UV, XPS, H2-TPR, and in situ FT-IR were used to characterize these catalysts. Results suggested that the incorporation of copper and manganese species resulted in the lattice expansion and the decease of microstrain of ceria–zirconia, thus inducing the formation of oxygen vacancies. There was a strong interaction between surface copper, manganese, and the support via charge transfer. The addition of manganese species could promote the reduction of the resultant catalysts and assist copper oxide in changing the valence and the support in supplying oxygen. These reduction behaviors were dependent on the loading amounts of MnO x and the impregnation procedure. In addition, the introduction of MnO x cannot change the adsorption type of NO, but readily helped to activate the adsorbed NO species. As a result, these factors were responsible for the enhancement of activity and selectivity through MnO x modification. [Copyright &y& Elsevier]

Abstract: There is an increasing interest to find cost-effective methods to produce graphene. It is common to produce graphene from the reduction of graphene oxide colloids. The key to this method’s success and producing graphene layers is having stable colloids of graphene and graphene oxide. The objective of this paper is to study the characteristics of a polymeric stabilizing agent that ensures stabilization of both graphene and graphene oxide. After providing a theoretical basis for selecting a proper polymer, experimental evaluations are performed to show that only proper polymers with the right molecular weight can serve as the stabilizing agent for both graphene and graphene oxide. [Copyright &y& Elsevier]

Abstract: Novel hybrid material thin films based on polyvinyl alcohol (PVA)/tetraethyl orthosilicate (TEOS) with embedded silver nanoparticles (AgNps) were synthesized using sol–gel method. Two different strategies for the synthesis of silver nanoparticles in PVA/TEOS matrix were applied based on reduction of the silver ions by thermal annealing of the films or by preliminary preparation of silver nanoparticles using PVA as a reducing agent. The successful incorporation of silver nanoparticles ranging from 5 to 7nm in PVA/TEOS matrix was confirmed by TEM and EDX analysis, UV–Vis spectroscopy and XRD analysis. The antibacterial activity of the synthesized hybrid materials against etalon strains of three different groups of bacteria –Staphylococcus aureus (gram-positive bacteria), Escherichia coli (gram-negative bacteria), Pseudomonas aeruginosa (non-ferment gram-negative bacteria) has been studied as they are commonly found in hospital environment. The hybrid materials showed a strong bactericidal effect against E. coli, S. aureus and P. aeruginosa and therefore have potential applications in biotechnology and biomedical science. [Copyright &y& Elsevier]

Abstract: Monodisperse silver particles were synthesized according to the method of Creighton et al. by reduction of AgNO3 solutions with NaBH4 in the presence of polyvinyl alcohol as the stabilizing agent. Bulk characteristics of silver nanoparticles in aqueous solutions were carried out by measuring their extinction spectrum, fluorescence, diffusion coefficients using the PCS method and the electrophoretic mobilities. The average hydrodynamic diameter of PVA covered silver particles was 44nm, being fairly independent of ionic strength and pH in the range of 3–9. It was also shown that the hydrodynamic radius did not change within prolonged storage of suspensions (up to 75days), indicating that the sols were quite stable. A similar value of 45±8nm was determined from SEM measurements. The electrophoretic mobility measurements showed that the zeta potential of silver nanoparticles was insensitive to pH and decreased with the ionic strength, attaining −45mV for I =10−5 M and −25mV for I =10−2 M. Additionally, the kinetics of silver particle deposition on mica modified by adsorption of a saturated layer of poly(ethylene imine) (PEI) was studied. Surface concentration was determined directly by counting the number of particles over various surface areas using the atomic force microscopy working in the semicontact mode. The maximum surface concentration for I =10−3 M was 102μm−2, which corresponds to the coverage degree of 16%. The kinetic run and the maximum coverage value was in a good agreement with theoretical predictions stemming from the random sequential adsorption (RSA) model. This kinetic run allowed one to determine the size of Ag core, which was 20nm and the thickness of the PVA layer, equal to 12nm. [Copyright &y& Elsevier]

Abstract: Silver particles (Ag particles) were synthesized by the photoreduction of silver perchlorate (AgClO4) in water-in-ionic liquid (IL) microemulsions consisting of nonionic surfactant Tween 20, water, and ionic liquids, [1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]) or 1-octyl-3-methylimidazolium tetrafluoroborate ([OMIm][BF4])], mixed with a high-pressure (25MPa) CO2. The time evolution of the Ag particle formation by photoreduction was investigated by UV–Vis, cryo-TEM, extended X-ray absorption fine structure (EXAFS), and small-angle X-ray scattering (SAXS) measurements. In the particle formation process, aggregation and precipitation of Ag particles were suppressed under high-pressure CO2. The average diameters of the metallic Ag particles prepared in water-in-[BMIm][BF4] and water-in-[OMIm][BF4] microemulsions were estimated from TEM to be 3.2 and 3.7nm, respectively. SAXS analysis shows that the average diameters of the water droplets, which consisted of ionic precursors of AgClO4 and Ag particles (or Ag aggregates), were estimated to be about 30–40nm. In the process of Ag particle formation, the water droplet size under high-pressure CO2 is more effectively regulated than that under ambient air, thereby preventing Ag particles from aggregating and precipitating. [Copyright &y& Elsevier]

Abstract: X-ray diffraction (XRD), Mössbauer spectroscopy, and temperature-programmed reduction (TPR) were employed to investigate the dispersion and reduction behaviors of the Fe2O3/CuO/γ-Al2O3 system. The results indicated that: (1) the crystalline CuO particle in the CuO/γ-Al2O3 samples was redispersed during impregnating CuO/γ-Al2O3 samples with Fe(NO3)3 solutions; (2) two different dispersion states of surface iron species could be observed, i.e., State I corresponding to the iron(III) species located in the D layer on the surface of γ-Al2O3 and State II corresponding to those in the C layer. The dispersed states of surface iron(III) species were closely related to the iron loading amount; (3) the copper species located in the D layer of alumina surface was easily reduced and the copper species located in the C layer were more stable, which could be due to the influence of the iron(III) species in the different layers; (4) in the NO+CO reaction, the catalytic performances were enhanced due to the Cu–Fe synergism and the main active species in this system should be the surface-dispersed copper oxide species. [Copyright &y& Elsevier]

Abstract: Synthesis of silver nanoparticles in homogeneous aqueous solutions of the precursors silver nitrate and three saccharides (two mono saccharides i.e. glucose and fructose and one disaccharide such as sucrose) has been performed. These Ag-nanoparticles can be derivatized by other surface treatments, as required. The anionic surfactant SDS was tested to investigate its effect on the dependence of size, growth rate, photoluminescence (PL) emission and polydispersity of the nanoparticles. The time evolution of UV–vis absorbance suggested that nucleation and growth rate markedly vary in a first order fashion w.r.t. Ag+ salt concentration. The differences in the reducing ability of the saccharides were discussed with reference to their structure dependent adsorption behavior onto the particles. Changes in UV–vis, PL and FT-IR spectra during nucleation and growth of the nanoparticles were used to establish plausible mechanisms for the adsorption of surfactant on the particle surface, so as to restrict the growth. The results revealed a simple and easy strategy for synthesizing metal nanoparticles with well controlled shapes, sizes and structures. [Copyright &y& Elsevier]

Abstract: Colloidal dispersions of silver (Ag) particles were prepared by the photoreduction of silver perchlorate (AgClO4) in water/AOT/benzene water-in-oil (w/o) microemulsions consisting of sodium bis(2-ethylhexyl) sulfosuccinate (AOT), water and benzene. Formation mechanisms of Ag particles prepared in the presence of benzoin by photoreduction from Ag+-containing w/o microemulsions were investigated by UV–vis, transmission electron microscopy (TEM), extended X-ray absorption fine structure (EXAFS) and small-angle X-ray scattering (SAXS) measurements. By a combination of TEM and EXAFS results, Ag particles show a metallic nature after the photoreduction and the diameter of Ag particles ranges between 5 and 30nm. In situ time-resolved SAXS measurements show that the integrated rate equation can be applied in the reduction process of Ag+ ions to Ag0 atoms, and the autocatalytic Ag particle growth proceeds in the association process of Ag0 atoms during the photoreduction of Ag+-containing w/o microemulsions. The nanometer-sized water droplets microemulsified by AOT in benzene continuous-phase regulated the size of Ag particles, and the size and shape of water droplets were retained during the Ag particle formation. [Copyright &y& Elsevier]

Abstract: A phase transformation induced by the reduction of as-synthesized γ-maghemite (γ-Fe2O3) nanoparticles was performed in solution by exploiting the reservoir of reduction gas (CO) generated from the incomplete combustion reaction of organic substances in the reactor. Results from X-ray diffraction, color indicator, and magnetic analysis using a SQUID strongly support this phase transformation. Based on this route, monodisperse magnetite (Fe3O4) nanoparticles were simply produced in the range from 260 to 300°C. Almost all aspects of the original γ-Fe2O3 nanoparticles, such as shape, size, and monodispersity, were maintained in the produced Fe3O4 nanoparticles. [Copyright &y& Elsevier]

Abstract: Metal particles of silver (Ag) were synthesized by the photoreduction of silver perchlorate (AgClO4) in water-in-ionic liquid (ILs) microemulsions consisting of Tween 20, water and ionic liquids. The ILs were tetrafluoroborate anions associated with the cations 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]) and 1-octyl-3-methylimidazolium tetrafluoroborate ([OMIm][BF4]). The time evolution of Ag particle formation by photoreduction using UV-irradiation was investigated by UV–Vis, cryo-TEM, extended X-ray absorption fine structure (EXAFS) and small angle X-ray scattering (SAXS) measurements. The average diameter of the metallic Ag particles prepared in the water-in-[BMIm][BF4] and water-in-[OMIm][BF4] microemulsions was estimated from TEM to be 8.9 and 4.9nm, respectively, which was consistent with that obtained from the SAXS analysis. Using Guinier plots in a low q-range (<0.16nm−1), we demonstrate that the average diameter of the water droplets that consisted of aggregates of ionic precursors of AgClO4 before reduction and Ag particles after reduction, in the microemulsions, was estimated to be about 20–40nm. The diameter of the water droplets increased as a function of photoreduction time because of the formation of Ag particles and their aggregates. EXAFS analysis indicated that Ag+ ions were completely reduced to Ag0 atoms during the photoreduction, followed by the formation of larger Ag particles. [Copyright &y& Elsevier]

Abstract: We describe the preparation and characterisation of inorganic–organic hybrid block copolymer silver nanoparticles via the preparation of spherical multi-responsive polymeric micelles of poly(N-methyl-2-vinyl pyridinium iodide)-block-poly(ethylene oxide), P2MVP38-b-PEO211 and poly(acrylic acid)-block-poly(isopropyl acrylamide), PAA55-b-PNIPAAm88 in the presence of AgNO3. Hence, the P2MVP and PAA segments were employed to fix Ag+ ions within the micellar core (25°C) or shell (60°C), while the PEO segments ensured spontaneous reduction of Ag+ ions into metallic Ag, as well as colloidal stabilisation. Spherical and elongated composite core–shell(–corona) nanoparticles (CNPs) were formed containing several small, spherical silver nanoparticles within the micellar core or shell. As the co-assembly of the oppositely charged copolymers into micelles is electrostatically driven, the CNPs can be destabilised by, for example, addition of simple salts, i.e., the CNPs are stimuli responsive. CNP size and morphology control can be achieved via the preparation protocol. For example, heating to 60°C, i.e., above the PNIPAAm LCST, results in core–shell–corona CNPs with the Ag-NPs situated in the aggregate shell. [Copyright &y& Elsevier]

Abstract: Raspberry-like composites were prepared by coating the silver/polypyrrole core/shell composites onto the surface of silica spheres via oxidation polymerization of pyrrole monomer with [Ag(NH3)2]+ ions as oxidants. The whole process allowed the absence of stabilizers, which greatly improved the quality of the conducting polymer composites. The morphology of the resulting composites was investigated, which can be described as raspberry-like; also, the structure and composition of the composites were characterized in detail. A possible formation mechanism was proposed. The present synthetic strategy substantially extended the scope of metal/conducting polymer composite synthesis. The raspberry-like composites exhibited excellent catalytic properties in the reduction of methylene blue dye with the reducing agent of sodium borohydride. [Copyright &y& Elsevier]

Abstract: Formation mechanisms of silver (Ag) particles in an aqueous ethanol solution of poly(N-vinyl-2-pyrrolidone) (PVP) by the photoreduction of AgClO4 were investigated by using UV–Vis, transmission electron microscopy (TEM), extended X-ray absorption fine structure (XAFS), and in situ energy-dispersive X-ray absorption fine structure (in situ DXAFS) measurements. The average diameter of the Ag particles prepared in the presence and absence of benzoin as a photo-activator was estimated from TEM to be 7.4 and 5.1nm, respectively, and their particle size distributions ranged from 2 to 15nm. XAFS analysis indicated that metallic Ag particles were synthesized, and the reduction rate of Ag+ to Ag0, the creation of Ag0–Ag0 bonds and their particle growth by the association of Ag0–Ag0 was regulated by the metal concentration and the inclusion of benzoin. In situ DXAFS measurements were performed in real time to investigate the kinetics of Ag+ reduction and Ag particle formation. During the induction period the reduction of Ag+ to Ag0 occurred, and subsequent nucleation and growth process concurrently proceeded after the induction period. The intermediate small Ag particles (C.N. smaller than about 4) were generated in the nucleation process, and grown up to larger particles (C.N.s equal to 4.5±1.5) in the longer-duration photoreduction. [Copyright &y& Elsevier]

Abstract: Alloy catalysts of Pt–Au/C with various Pt/Au ratios were prepared for an oxygen reduction reaction (ORR). The structure, surface species, surface compositions, and electrocatalytic activities of prepared alloy catalysts were characterized by XRD, TPR, XPS, and rotating disk electrode (RDE) techniques, respectively. It was observed that the ORR activity of the Pt75Au25/C alloy catalyst was enhanced significantly in comparison to the commercial Pt/C catalyst within the mixed kinetic-diffusion control region. The alloying with Au modified the oxophilicity of Pt–Au alloy catalysts. TPR characterization suggests that the enhancement of Pt75Au25/C was attributed to the formation of an alloy surface, having a moderate oxophilicity and a Pt-related alloy surface species. [Copyright &y& Elsevier]

Abstract: A novel route is proposed to produce graphite nanoplatelets (GNPs) and graphene sheets. The natural graphite flakes were directly exfoliated by ultrasonication in formic acid. A stable graphene aqueous dispersion was obtained using the as-produced GNPs after two processing steps: (i) chemical oxidation of GNPs to graphite oxide nanoplatelets (GONPs); and (ii) chemical reduction of graphite oxide nanoplatelets to graphene. The total duration for oxidation and production of stable graphite oxide colloid was significantly shortened due to the use of exfoliated GNPs with large surface area. The work proposed here has several advantages over the previous methods, including a high efficiency of exfoliation process, the use of a non-toxic, environmental-friendly intercalant and the capability for mass production of graphene for industrial applications. [Copyright &y& Elsevier]

Abstract: Stable concentrated aqueous dispersions of monodisperse gold nanoparticles were prepared using diethylaminoethyl-dextran as reductant and stabilizer. The effectiveness of dextran as reducing agent was strongly affected by the pH. In alkaline solutions, the Au(III) species were rapidly and completely reduced, yielding stable dispersions of spherical uniform gold nanoparticles. Their modal diameter could be adjusted from 18 to 40nm by varying the pH, temperature, and the Au3+/dextran ratio. In contrast, under acidic conditions (pH∼4.0) the reduction was very slow, favoring the formation of large gold crystals of other shapes. A general mechanism explaining the reducing and stabilizing actions of polysaccharides in general, and of diethylaminoethyl-dextran in particular, is proposed. [Copyright &y& Elsevier]

Abstract: Uniform stable nanosize nickel platelets were prepared by first coating Ni(OH)2 particles of the same shape with gelatin and then heating them at moderate temperatures in nitrogen without addition of any reducing agents. The resulting platelets consist of a mixture of Ni and NiO. Depending on the amount of gelatin coating and temperature, up to 73% of solids were converted to the metal. Subsequent heating of such powders at 190°C in a stream of 5% H2 in N2 produced only Ni platelets with a modal length of ∼60nm and several nm thick. [Copyright &y& Elsevier]

Abstract: The paper presents a time-dependent study of shape-dependent preferential complexation of gold nanoparticles to the octadecyl amine (ODA) monolayers at the air–water interface. Room temperature reduction of chloroaurate ions using lemon grass leaf extract yields a mixture of spherical and triangular nanoparticles, which were used for this study. These nanoparticles have a net negative charge on their surface due to the presence of biomolecules from plant extract and thus a strong attractive electrostatic interaction with the positively charged ODA monolayers drives the complexation process. The extent of preferential complexation of the gold nanoparticles to the ODA monolayers is a function of the charge on the particles and the relative mobility of the nanoclusters in the medium. The complexation process has been followed in real time by a host of techniques such as surface pressure–area isotherms, UV–vis–NIR spectroscopy and Brewster angle microscopy. The charge and mobility of the gold nanoparticles was confirmed by measurement of their electrophoretic mobility. Langmuir–Blodgett films of the nanogold–ODA composites have been characterized by UV–vis–NIR spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. These measurements clearly indicate that the cluster mobility and complexation increase with decreasing cluster size. In the competitive complexation process of large and small gold particles, it was observed that some bigger gold particles were also incorporated into the amine matrix even though the cluster mobility is higher for smaller gold particles. [Copyright &y& Elsevier]

Abstract: On the basis of the understanding that membranes play an important role in the separation of the intermediate photoproducts in the photosynthetic process, a novel efficient hydrogen evolution system was constructed with Maya blue-like organic–inorganic hybrid material as a photocatalyst, in which palygorskite acts as matrix and Eosin Y as a photosensitizer. Under visible light irradiation (), the highest rate of hydrogen evolution and apparent quantum yield are about 3247.2 μmol h−1 (g Eosin Y)−1 and 12.5%, respectively. Negatively charged palygorskite particles could control the photosensitized electron-transfer reaction by means of electrostatic interaction. Based on the activities of hydrogen generation and the experimental measurements of UV–vis absorbance and fluorescence, a probable mechanism for photosensitized hydrogen evolution was postulated. [Copyright &y& Elsevier]

Abstract: The translational diffusion of Au (gold) ions and Au particles during the photoreduction process from AuCl− 4 to metallic Au particles in aqueous ethanol solutions containing poly(N-vinyl-2-pyrrolidone) was investigated by using UV–vis absorption and the laser-induced transient grating (TG) methods. The TG signal of AuCl− 4 solution before photoirradiation was composed of three contributions; the thermal grating, the species grating due to the creation of AuCl− 2, and that due to the depletion of AuCl− 4. Upon photoirradiation, the species grating signal due to AuCl− 4 diminished rapidly and the TG signal due to Au particles appeared within a few minutes and became stronger at a very short time. The subsequent reduction of AuCl− 2 was concomitant with the formation of Au metal particles. The rapid growth of Au0 atoms into Au particles took place in the short-duration photoirradiation. With the increase of the photoirradiation time, the TG signal was composed of two kinds of Au particle fragments possessing different diffusion coefficients. This is probably due to the pulse-laser induced fragmentation of the larger Au particles. Effects of the polymer on the particle formation were investigated by the concentration dependence of the polymer in the solution. The formation of Au particles by the photoreduction was also compared with that of Pt particles. [Copyright &y& Elsevier]

Abstract: A series of bimetallic NiAg (Ni+Ag=1% wt) catalysts supported on amorphous silica was synthesized via chemical reduction using hydrazine as the reducing agent at 353 K. Catalysts were prepared via impregnation or precipitation technique. It was found that the reduction of the Ni2+ ions occurred only in the presence of silver, otherwise a stable blue [Ni(N2H4)3]2+ complex was formed. Comparisons with similar NiAg catalysts supported on crystallized silica as prepared in our previous work indicated that the Ni2+ ions weakly interacted with acidic crystallized silica on which they were readily reduced. For both supports, the combination of silver and nickel gave rise to a synergistic effect due to the existence of NiAg groupings. The surface and catalytic properties of the metal particles formed depended on the Ni:Ag ratio, method of preparation, and acidity of the support. [Copyright &y& Elsevier]

Abstract: It has been observed that, at , [Co(NH3)6](ClO4)3, [Co(en)3](ClO4)3, [Co(bpy)3](ClO4)3, and [Co(phen)3](ClO4)3 in the regions of 1.25–5.00 mM aqueous solutions cause a significant surface tension reduction (STR) of water by the surfactants, sodium dodecylsulfate (SDS) and sodium dodecylbenzenesulfonate (SBS), suggesting the formation of the 1:1 and 1:2 association complexes, {[complex]3+(S−)}2+ and {[complex]3+(S−)2}+ where [complex]3+ =[Co(NH3)6]3+, [Co(en)3]3+, [Co(bpy)3]3+, or [Co(phen)3]3+, S− =DS− or BS−. The effect of [Co(en)3]3+ on STR in SDS–water system is the largest due to a strong hydrophilic interaction between amino protons of [Co(en)3]3+ and sulfate oxygen atoms of DS−. The effects of [Co(en)3]3+, [Co(bpy)3]3+, and [Co(phen)3]3+ on STR in SBS–water system are significant and almost same, meaning that the hydrophilic interaction between [Co(en)3]3+ and the sulfonate group is comparable to the hydrophobic interaction between [Co(bpy)3]3+ or [Co(phen)3]3+ and the phenyl group of BS−. The Co(III) complexes of 1.25–5.00 mM are precipitated as {[complex]3+(S−)3} at 0.0295–0.173 mM of S−. The precipitates, {[Co(bpy)3]3+(S−)3} and {[Co(phen)3]3+(S−)3} can be dissolved at higher molar ratio of [S−]/[complex3+] than 3.5 for SDS and 4.0 for SBS. This observation suggests that the aggregated premicelle [Co(bpy or phen)3]2(DS)− 7 or aggregated premicelle [Co(bpy or phen)3](BS)− 4 is formed. [Copyright &y& Elsevier]

Abstract: Hydrotalcite-supported Pd/Sn catalysts with different Mg/Al atomic ratios (2, 3, 4, and 5) for nitrate adsorption and hydrogenation reduction were successfully synthesized by a coprecipitation method. The results showed that different atomic ratios of Mg/Al resulted in different interlayer spacings and zeta-potentials of the catalysts, which thus influenced its adsorption capacity. With the increase of Mg/Al atomic ratio, the interlayer spacing rose and zeta-potential decreased. The adsorption properties of the catalysts were mainly affected by interlayer spacing when Mg/Al atomic ratios increased from 2 to 4. However, when Mg/Al atomic ratios further increased from 4 to 5, there was a negative impact on the adsorption properties of zeta-potential. Also, the adsorption capacity of the catalysts for nitrate followed the order: Mg/Al=2

Abstract: We studied the phase diagrams of microemulsions with a view to using these systems for the synthesis of metallic Pt, Pb, and Bi nanoparticles as well as of intermetallic Pt/Pb and Pt/Bi nanoparticles. The microemulsions consisted of H2O/salt–n-decane–SDS–1-butanol. The salt was either one metal precursor (H2PtCl6⋅6H2O, Pb(NO3)2, or Bi(NO3)3⋅5H2O), a mixture of two metal precursors (H2PtCl6⋅6H2O+Pb(NO3)2 or H2PtCl6⋅6H2O+Bi(NO3)3⋅5H2O), or the reducing agent (NaBH4). In addition, other salts needed to be added in order to solubilize the metal precursors, to stabilize the reducing agent, and to adjust the ionic strength. Combining the microemulsion (μe1) that contains the metal precursor(s) with the microemulsion (μe2) that contains the reducing agent leads to metallic nanoparticles. To study systematically how the shape and size of the synthesized metallic nanoparticles depend on the size and shape of the respective microemulsion droplets, first of all one has to find those conditions under which μe1 and μe2 have the same structure. For that purpose we determined the water emulsification failure boundary (wefb) of each microemulsion as it is at the wefb where the water droplets are known to be spherical. We found that the ionic strength (I) of the aqueous phase as well as the hard acid and hard base properties of the ions are the key tuning parameters for the location of the wefb. [Copyright &y& Elsevier]

Abstract: Understanding shape control during wet chemical synthesis is important for rational synthesis of nanostructures. Here, we show that two-dimensional metal structures can be obtained from metal salts by reducing the driving force of the reduction reaction that directly translates to the growth of the metal taking place by the two-dimensional nucleation (layer-by-layer growth) mechanism. Experimental evidence is provided for Au, Ag, Pt and Pd systems by choosing appropriate reaction conditions without using any external surfactant. The results are analyzed in terms of the calculations of driving force under different conditions. The results show that surfactants may not be important for producing shape control for the case of 2-D structures while they are required to obtain size control. It is shown that the regime of low driving force is also one where the kinetics of the process is slow and thus a new interpretation of the kinetic control hypothesis is provided. [Copyright &y& Elsevier]

Abstract: Large-scale syntheses of Prussian Blue (PB) uniform nanocubes and nanospheres, together with an interesting PB micro-frame structure, have been achieved by direct dissociation of a single-source precursor K3[Fe(CN)6] with polyvinylprrolidone (PVP) as a capping and reducing agent. The reaction temperature has been proved to be a key factor for morphology development of PB nanocrystals, and the size of PB nanocrystals can be tuned by adjusting the feed ratio of K3[Fe(CN)6] to PVP and the concentration of K3[Fe(CN)6]. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), and high resolution transmission electron microscopy (HRTEM) were used to characterize the resulting nanocrystals and investigate their growth mechanisms. Optical and magnetic studies showed size- and shape-dependent optical and magnetic properties in the PB nanocrystals. An excellent electro-catalytic property to hydrogen peroxide reduction was observed at the PB nanocube-modified electrode. [Copyright &y& Elsevier]

Abstract: Multi-branched gold nanoparticles were synthesized in high-yield through the reduction of HAuCl4 by using hydrazine as a reducing agent. Practically 100% of the particles have numerous branches. The high reduction capability of hydrazine is found to be crucial for the formation of these branched gold nanoparticles. Their size can be controlled from 20 to 130 nm by varying the amounts of hydrazine. The prepared nanoparticles exhibit efficient surface-enhanced Raman scattering (SERS) properties and the SERS activity of the particles depends on the aspect ratio of their branches, which are most likely related to a great increase in the localized electromagnetic field enhancement from their unique sharp surface features arising from the branches. [Copyright &y& Elsevier]

Abstract: In this contribution, self-assembled monolayers of n-dodecanethiol (C12H25SH) at different concentrations on polycrystalline copper have been elaborated. Using XPS, PM-IRRAS, and electrochemical methods (cyclic voltammetry curves and cathodic desorption), the effect of the C12H25SH concentration on the reduction of the oxide layer has been studied. In all cases, a monolayer of good quality has been obtained. Results provide proof that while the concentration is increased, the thickness of the oxide layer is decreased, to a point that leads to metallic copper for the higher concentration. The results presented in this publication indicate the importance of controlling the interface when forming SAMs of organothiols on oxidizable metals. [Copyright &y& Elsevier]

Abstract: Silver nanoparticles (AgNPs) are synthesized by chemical reduction method and characterized by UV–vis spectra, transmission electron microscopy, and high performance particle sizer. We have found that AgNPs could enhance the chemiluminescence (CL) intensity of luminol–H2O2 system. In this reaction, luminol intermediate is generated under alkaline condition on the surface of AgNPs in luminol–H2O2 system and enhances CL intensity. To validate the reaction mechanism, AgNPs are bound with thioglycolic acid (Ag–HSCH2COOH) and then joined to BSA protein (Ag–BSA). We investigate the CL intensity in the presence of Ag–HSCH2COOH or Ag–BSA comparing with that in the presence of AgNPs and conclude the catalytic reaction take place on the surface of AgNPs. [Copyright &y& Elsevier]

Abstract: Platinum nanoparticles are homogeneously immobilized onto the polystyrene surface using alcohol-reduction method for the first time. Sulfonate groups were employed as a chemical protocol to make a binding between platinum nanoparticle and polystyrene surface. A large number of quasi-spherical platinum nanoparticles with a size of ∼5 nm in diameter are formed and strongly attached to the polystyrene surface modified with sulfonate groups. The formation mechanism of composite materials was discussed briefly. The most distinguished features of this novel preparation route include simple operation, and absence of the toxic reducing agent. In addition, this novel preparation route can be extended to the preparation of other noble metal–polymer heterogeneous nanocomposites such as silver, gold, palladium, iridium and ruthenium. [Copyright &y& Elsevier]

Abstract: Au/TiO2 nanocomposites have been prepared by UV photolysis or chemical reduction of a Au(III) complex formed on a spherical or a rodlike TiO2 support, and their catalytic activity for 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging reaction was investigated. The chemical reduction with dimethylamine borane (DMAB) provided smaller gold nanoparticles than those synthesized by UV photolysis. Type of the TiO2 also affected the size of gold particles; smaller gold particles were deposited on the spherical TiO2 support than on rodlike one. For the radical scavenging reaction, the Au/TiO2 nanocomposites prepared by chemical reduction exhibited a higher catalytic activity than those photochemically prepared, and rodlike TiO2 provided a higher activity than spherical one. The effects of preparation methods and type of TiO2 supports on the catalytic activity are discussed. [Copyright &y& Elsevier]

The rate of reduction of Cr(VI) to Cr(III) in 0.05 M K2Cr2O7 has been studied and was found to be first order. The rate of reaction was measured in the absence of amino compounds and in the presence of o-nitroaniline, p-nitroaniline, m-toulidine, p-chloroaniline, and o-bromoaniline at four different temperatures. The rate of reaction was found to decrease with the addition of amines. Thermodynamic parameters , , and were calculated from the study. [Copyright &y& Elsevier]

We report on the reduction of aqueous chloroaurate ions by glucose to form gold nanoparticles of uniform size. We further demonstrate the complexation of these particles with octadecylamine (ODA) monolayers at the air–water interface. Pressure–area (π–A) isotherms as a function of time of complexation revealed a significant expansion of the monolayer. Surface pressure variation with time for constant areas after spreading of the monolayer was carried out to observe the kinetics of complexation of the colloidal particles at the interface. The kinetics of complexation of the particles at the interface was also monitored by Brewster angle microscopy (BAM) measurements. Langmuir–Blodgett films of the particles complexed with ODA were formed at a subphase pH of 9 onto different substrates. Quartz crystal microgravimetry (QCM) was used to quantify the amount of particles deposited per immersion cycle of the quartz crystal. The LB films were further characterized by UV–vis and transmission electron microscopy (TEM) measurements. TEM measurements indicate a close packed and equidistant arrangement of colloidal particles in the LB film, probably due to hydrogen-bonding interactions. [Copyright &y& Elsevier]

The reduction of ferrofluid (FF) by L-ascorbic acid (H2A) and the reoxidation of the reduced FF to its original form by hydrogen peroxide have been investigated in aqueous acidic medium. The rate of reduction of FF was found to be first order with respect to [H2A] and [FF] and independent with respect to [H2O2] and ionic strength. The rate of reduction of FF increased with increasing pH (2.5–4.0), having an inverse first order dependence in [H+]. With increasing temperature (15–45 °C), the rate of reduction was increased in line with the Arrhenius equation. Based on experimental evidence and results a mechanism, operative to reduce FF and reoxidize the reduced FF by H2O2, which makes the system catalytic, is suggested. Thermodynamic quantities associated with FF-catalyzed oxidation of H2A by H2O2 were determined and compared with other closely related systems. [Copyright &y& Elsevier]

Nanocrystalline CoxNiyCu100−x−y particles were synthesized by the reduction of metal acetates in a mixture of polyol and Tween 80. Inductively coupled plasma (ICP) analysis revealed that the actual wt% of Co, Ni, and Cu in these nanoparticles was nearly the same as in the starting solutions. The structures of the particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) spectroscopy, and vibrating sample magnetometry (VSM). The results of XRD and VSM confirmed that there was no metastable alloying in the particles. The particles were composites, consisting of nanoscale crystallites of face-centered cubic (fcc) Cu, face-centered cubic (fcc) Ni, and face-centered cubic (fcc) Co. During preparation the nucleation of Cu occurred first; then small Cu nuclei acted as cores for the precipitation of Co and Ni. The particles showed an increase in saturation magnetization (Ms) as the concentration of Co or Ni in the particles was increased. The changes of both Ms and coercivity of the particles with increasing annealing temperatures were studied. The coercivity of the particles was very high; it could reach as high as 489 Oe for Co34.3Ni31.2Cu34.5. [Copyright &y& Elsevier]

The reduction of colloidal MnO2 by Mn2+ in aqueous HClO4 has been studied by a spectrophotometric method. The reaction product is Mn(III). The reaction is of first order in both colloidal MnO2 and H+, whereas it presents a fractional order (0.58±0.02) in Mn2+. The reaction is retarded by addition of NaClO4, but is not affected by addition of tert-butanol. The corresponding activation energy is 29.5±1.3 kJ mol−1. The reaction is catalyzed by Na4P2O7, and the pyrophosphate-catalyzed reaction is of first order in both colloidal MnO2 and pyrophosphate and of fractional order (0.64±0.01) in Mn2+, whereas its rate presents a complex dependence on the concentration of H+. The pyrophosphate-catalyzed reaction is accelerated by addition of both NaClO4 and tert-butanol. The corresponding activation energy is 49.7±3.0 kJ mol−1. Mechanisms in agreement with the experimental data are proposed for both the parent and the pyrophosphate-catalyzed reactions. [Copyright &y& Elsevier]