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Reduction Reaction (reduction + reaction)
Kinds of Reduction Reaction Selected AbstractsHeterogeneous Electron Transfer and Oxygen Reduction Reaction at Nanostructured Iron(II) Phthalocyanine and Its MWCNTs NanocompositesELECTROANALYSIS, Issue 9 2010Solomon Abstract Electron transfer and oxygen reduction dynamics at nanostructured iron(II) phthalocyanine/multi-walled carbon nanotubes composite supported on an edge plane pyrolytic graphite electrode (EPPGE-MWCNT-nanoFePc) platform have been reported. All the electrodes showed the category 3 diffusional behaviour according to the Davies,Compton theoretical framework. Both MWCNTs and MWCNT-nanoFePc showed huge current responses compared to the other electrodes, suggesting the redox processes of trapped redox species within the porous layers of MWCNTs. Electron transfer process is much easier at the EPPGE-MWCNT and EPPGE-MWCNT-nanoFePc compared to the other electrodes. The best response for oxygen reduction reaction was at the EPPGE-MWCNT-nanoFePc, yielding a 4-electron process. [source] Bioelectrocatalysis of Oxygen Reduction Reaction by Laccase on Gold ElectrodesELECTROANALYSIS, Issue 13-14 2004Gautam Gupta Abstract Direct electron transfer (DET) reaction of oxygen electroreduction catalyzed by enzyme laccase on monolayer modified gold electrodes was studied. Three different monolayers were investigated, from which 4-aminothiophenol was found to be optimal for the direct electron transfer to take place. The electrocatalytic reduction of the oxygen at the electrode surface was found to depend significantly on the method of immobilization. Fungal laccase from Coriolus hirsitus modified with sodium-periodate demonstrated more anodic onset potential for oxygen reduction than the tree laccase from Rhus vernicifera. Physical immobilization of enzyme did not result in any manifestation of bioelectrocatalytic activity. A maximum anodic shift in reduction potential of 300,mV was observed for fungal laccase covalently coupled on the electrode surface. [source] High Performance Carbon-Supported Core@Shell PdSn@Pt Electrocatalysts for Oxygen Reduction ReactionFUEL CELLS, Issue 4 2010W. Zhang Abstract In this report, a low-cost and high performance PdSn@Pt/C catalyst with core,shell structure is prepared by two-stage route. X-ray diffraction (XRD) and transmission electron microscopy (TEM) examinations show that the composite catalyst particles distribution is quite homogeneous and has a high surface area and the PdSn@Pt/C catalyst has an average diameter of ca. 5.6,nm. The oxygen reduction reaction (ORR) activity of PdSn@Pt/C was higher than commercial Pt/C catalyst. Catalytic activity is studied by cyclic voltammetry. High electrocatalytic activities could be attributed to the synergistic effect between Pt and PdSn. [source] Application of Electrochemical Impedance Spectroscopy for Fuel Cell Characterization: PEFC and Oxygen Reduction Reaction in Alkaline Solution,FUEL CELLS, Issue 3 2009N. Wagner Abstract The most common method used to characterise the electrochemical performance of fuel cells is the recording of current/voltage U(i) curves. Separation of electrochemical and ohmic contributions to the U(i) characteristics requires additional experimental techniques like electrochemical impedance spectroscopy (EIS). The application of EIS is an approach to determine parameters which have proved to be indispensable for the characterisation and development of all types of fuel cell electrodes and electrolyte electrode assemblies [1]. In addition to EIS semi-empirical approaches based on simplified mathematical models can be used to fit experimental U(i) curves [2]. By varying the operating conditions of the fuel cell and by the simulation of the measured EIS with an appropriate equivalent circuit, it is possible to split the cell impedance into electrode impedances and electrolyte resistance. Integration in the current density domain of the individual impedance elements enables the calculation of the individual overpotentials in the fuel cell (PEFC) and the assignment of voltage loss to the different processes. In case of using a three electrode cell configuration with a reference electrode, one can directly determine the corresponding overvoltage. For the evaluation of the measured impedance spectra the porous electrode model of Göhr [3] was used. This porous electrode model includes different impedance contributions like impedance of the interface porous layer/pore, interface porous layer/electrolyte, interface porous layer/bulk, impedance of the porous layer and impedance of the pores filled by electrolyte. [source] Electrocatalysts: Facile Construction of Pt,Co/CNx Nanotube Electrocatalysts and Their Application to the Oxygen Reduction Reaction (Adv. Mater.ADVANCED MATERIALS, Issue 48 200948/2009) Pt,Co alloyed nanoparticles can be facilely immobilized onto CNx nanotubes due to the incorporated nitrogen, report Yanwen Ma, Zheng Hu, and co-workers on p. 4953. The as-prepared electrocatalysts exhibit good performance for oxygen reduction reactions in acidic media arising from the high dispersion and alloying effect of Pt,Co nanoparticles, as well as the intrinsic catalytic capacity of CNx nanotubes, which is significant for the development of fuel cells. [source] Facile Construction of Pt,Co/CNx Nanotube Electrocatalysts and Their Application to the Oxygen Reduction ReactionADVANCED MATERIALS, Issue 48 2009Shujuan Jiang A straight forward method for immobilizing Pt,Co alloyed nanoparticles onto nitrogen-doped CNx nanotubes is presented (see image). The as-prepared electrocatalysts exhibit good performance for oxygen reduction reaction in acidic medium arising from the high-dispersion and alloying effect of the Pt,Co nanoparticles and the intrinsic catalytic capacity of the CNx nanotubes. [source] A Novel Reduction Reaction for the Conversion of Aldehydes, Ketones and Primary, Secondary and Tertiary Alcohols into Their Corresponding Alkanes.CHEMINFORM, Issue 46 2006Rama D. Nimmagadda Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Oxygen Reduction Reaction at Three-Phase Interfaces,CHEMPHYSCHEM, Issue 13 2010Dr. Ram Subbaraman Abstract The kinetics of the oxygen reduction reaction (ORR) is studied at metal,supporting electrolyte,Nafion three-phase interfaces. We first demonstrate that the sulfonate anions of Nafion are specifically adsorbed on a wide range of surfaces ranging from Pt(hkl) single-crystal surfaces, Pt-poly, Pt-skin [produced on a Pt3Ni(111) surface by annealing in ultrahigh vacuum, UHV] to high-surface-area nanostructured thin-film (NSTF) catalysts. The surface coverage by sulfonate and the strength of the Pt,sulfonate interaction are strongly dependent on the geometry and the nature of the Pt surface atoms. Also, they are found to behave analogous to (bi)sulfate anion-specific adsorption on these surfaces, where for the Pt(hkl) surfaces, the trend is Pt(111)>Pt(110)>Pt(100) and for the Pt-skin surface on Pt3Ni(111), the interaction strength is found to be Pt-skin ChemInform Abstract: Synthesis of Yb Complexes with Amino-Acid-Armed Ligands for Direct Asymmetric Tandem Aldol Reduction Reactions.CHEMINFORM, Issue 11 2009Maciej Stodulski Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Preparation and Novel Reduction Reactions of Vinamidinium Salts.CHEMINFORM, Issue 25 2001Ian W. Davies Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Reduction of Limonene Chlorohydrins in Commercial Citrus OilsJOURNAL OF FOOD SCIENCE, Issue 1 2005Robert J. Braddock ABSTRACT: Commercial cold-pressed citrus oils containing terpene chlorohydrins may have quality and safety implications for end-users of these oils. Concentrations of (1S, 2S, 4R)-2-chloro-8- p -menthen-1-ol (1), (1R, 2R, 4R)-2-chloro-8- p -menthen-1-ol (2), and (1R, 2R, 4R)-2,9-dichloro-8- p -menthen-1-ol (3) in some citrus essential oils ranged from less than 1 ppm to 30 ppm measured by gas chromatography with a halogen detector. Reduction reactions of these compounds were accomplished by continuous mixing (reaction) of the oil with dilute solutions of KOH. Greater than 95% reduction of 1 and 3 were accomplished after reaction for 15 h with 0.5 N KOH or after 24 h with 0.25 N KOH in oils with either 25 or 30 ppm (1). Similar treatment of an oil containing 5 ppm (1) resulted in reduction to below the threshold limit of quantification (0.4 ppm). Sensory analyses of tasting solutions did not detect any flavor difference between untreated or KOH-treated oils. [source] THM and reactive transport analysis of expansive clay barrier in radioactive waste isolationINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 8 2006L. do N. Guimarães Abstract A fully coupled formulation combining reactive transport and an existing thermo-hydro-mechanical (THM) code is briefly described. Special attention has been given to phenomena likely to be encountered in clay barriers used as part of containment systems of nuclear waste. The types of processes considered in the chemical formulation include hydrolysis, complex formation, oxidation/reduction reactions, acid/base reactions, precipitation/dissolution of minerals and cation exchange. Both kinetically controlled and equilibrium-controlled reactions have been incorporated. The formulation has been implemented in the finite element code CODE_BRIGHT. An application is presented concerning the performance of a large scale in situ heating test simulating high-level nuclear waste repository conditions. Copyright © 2006 John Wiley & Sons, Ltd. [source] Heterogeneous Electron Transfer and Oxygen Reduction Reaction at Nanostructured Iron(II) Phthalocyanine and Its MWCNTs NanocompositesELECTROANALYSIS, Issue 9 2010Solomon Abstract Electron transfer and oxygen reduction dynamics at nanostructured iron(II) phthalocyanine/multi-walled carbon nanotubes composite supported on an edge plane pyrolytic graphite electrode (EPPGE-MWCNT-nanoFePc) platform have been reported. All the electrodes showed the category 3 diffusional behaviour according to the Davies,Compton theoretical framework. Both MWCNTs and MWCNT-nanoFePc showed huge current responses compared to the other electrodes, suggesting the redox processes of trapped redox species within the porous layers of MWCNTs. Electron transfer process is much easier at the EPPGE-MWCNT and EPPGE-MWCNT-nanoFePc compared to the other electrodes. The best response for oxygen reduction reaction was at the EPPGE-MWCNT-nanoFePc, yielding a 4-electron process. [source] Green Synthesis of Silver Nanoparticles Using Ionic Liquid and Application for the Detection of Dissolved OxygenELECTROANALYSIS, Issue 6 2010Tsung-Hsuan Tsai Abstract The electrochemical synthesis of silver nanoparticles (nano-Ag) has been successfully carried out on glassy carbon electrode (GCE) and indium tin oxide electrode (ITO) using 1-butyl-3-methylimidazolium tetrafluoroborate (BMT) as green electrolytes. Further the electrodeposited nano-Ag modified ITO electrode has been examined using atomic force microscopy (AFM), and X-ray diffraction studies (XRD). The electrodeposited Ag nanoparticles on ITO were found in the size range of 5 to 35,nm. The nano-Ag film modified GCE was further coated with nafion (Nf) and BMT (1,:,1 ratio) mixture and found to be stable in BMT and in pH,7 phosphate buffer solution (PBS). The nano-Ag/BMT-Nf film modified GCE successfully applied for the oxygen reduction reaction in neutral pH (pH,7.0 PBS). The proposed film modified GCE successfully reduces the over potential and show well defined reduction peaks for the detection of dissolved oxygen using cyclic voltammetry (CV) and rotating disc voltammetry (RDE). The film also applied for the detection of dissolved oxygen using electrochemical impedance spectroscopic studies (EIS). [source] Electrochemical Reduction of Oxygen on Carbon Supported Pt and Pt/Ru Fuel Cell Electrodes in Alkaline SolutionsFUEL CELLS, Issue 4 2003E.H. Yu Abstract A study of O2 reduction in 1 M NaOH solution at gas diffusion electrodes made from carbon supported Pt and Pt/Ru catalysts is reported. Two Tafel regions were observed for both the Pt and Pt/Ru electrodes. Although the same mechanism was suggested for oxygen reduction on both Pt and Pt/Ru catalysts, the O2 reduction activity was lower on Ru. Electrochemical Impedance Spectroscopy (EIS) analysis was carried out at different potentials and showed the significant contribution of diffusion on the reaction process and kinetics. The effect of methanol on O2 reduction was investigated in solutions containing various concentrations of methanol. The electrode performance deteriorated with increasing methanol concentration because of a mixed cathode potential. The methanol tolerance, i. e., the methanol concentration which polarises the O2 reduction reaction for O2 reduction, at the Pt/C electrode with a Pt loading of 1.2 mg cm,2 is 0.2 M methanol in 1 M NaOH. [source] Synthesis of Nanohole-Structured Single-Crystalline Platinum Nanosheets Using Surfactant-Liquid-Crystals and their Electrochemical CharacterizationADVANCED FUNCTIONAL MATERIALS, Issue 4 2009Tsuyoshi Kijima Abstract Nanohole-structured single-crystalline Pt nanosheets have been synthesized by the borohydride reduction of Na2PtCl6 confined to the lyotropic liquid crystals (LLCs) of polyoxyethylene (20) sorbitan monooleate (Tween 80) with or without nonaethylene-glycol (C12EO9). The Pt nanosheets of around 4,10,nm in central thickness and up to 500,nm or above in diameter have a number of hexagonal-shaped nanoholes ,1.8,nm wide. High-resolution electron microscope images of the nanosheets showed atomic fringes with a spacing of 0.22,nm indicating that the nanosheets are crystallographically continuous through the nanoholed and non-holed areas. The inner-angle distributions for the hexagonal nanoholes indicate that the six sides of the nanoholes are walled with each two Pt (111), Pt (11) and Pt (010) planes. The formation mechanism of nanoholed Pt nanosheets is discussed on the basis of structural and compositional data for the resulting solids and their precursory LLCs, with the aid of similar nanohole growth observed for a Tween 80 free but oleic acid-incorporated system. It is also demonstrated that the nanoholed Pt nanostructures loaded on carbon exhibit fairly high electrocatalytic activity for oxygen reduction reaction and a high performance as a cathode material for polymer-electrolyte fuel cells, along with their extremely high thermostability revealed through the effect of electron-irradiation. [source] Facile Construction of Pt,Co/CNx Nanotube Electrocatalysts and Their Application to the Oxygen Reduction ReactionADVANCED MATERIALS, Issue 48 2009Shujuan Jiang A straight forward method for immobilizing Pt,Co alloyed nanoparticles onto nitrogen-doped CNx nanotubes is presented (see image). The as-prepared electrocatalysts exhibit good performance for oxygen reduction reaction in acidic medium arising from the high-dispersion and alloying effect of the Pt,Co nanoparticles and the intrinsic catalytic capacity of the CNx nanotubes. [source] Site-Selective Deposition of Metal Nanoparticles on Aligned WO3 Nanotrees for Super-Hydrophilic Thin FilmsADVANCED MATERIALS, Issue 13 2009Masachika Shibuya Highly aligned WO3 nanotrees are grown on metal tungsten by a simple hydrothermal reaction. Pd nanoparticles are selectively deposited on the WO3 nanotrees by a photocatalytic reduction reaction. Photocatalytic oxidation activity depends strongly on the position of the deposited Pd nanoparticles, and the WO3 nanotrees with Pd nanoparticles deposited at the bottom position exhibited efficient super-hydrophilicity. [source] Synthesis and properties of amine-containing poly(arylene ether sulfone) as an anion-exchange matrixJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2002Won-Keun Son Abstract Poly(arylene ether sulfone) (PSF), showing good thermal stability and excellent mechanical properties, was synthesized as an anion-exchange matrix. It was synthesized by the condensation polymerization between bisphenol A and 4,4,-dichlorodiphenylsulfone. 1°-Amine-containing poly(arylene ether sulfone) (1°-APSF) was synthesized by the reduction reaction of a nitrated PSF. Then, it was transferred to 3°-amine-containing poly(arylene ether sulfone) (3°-APSF) by the alkylation of the amine of 1°-APSF. The properties of PSF, 1°-APSF, and 3°-APSF were investigated by Fourier transform infrared, 1H NMR spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. The introduction of the 3°-amine group into PSF increased the glass-transition temperature but decreased thermooxidative stability. The ion-exchange capacities of 1°-APSF and 3°-APSF were shown to be 2.24 and 2.86 mequiv/g, respectively. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4281,4287, 2002 [source] Electrochemical Behavior of Gel-Derived Lanthanum Calcium Cobalt Ferrite Cathode in Contact with LAMOX ElectrolyteJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2008Tsu-Yung Jin The electrochemical performance and structural features of (La1,yCay)(CoxFe1,x)O3 cathode prepared via a citrate acid gel route are studied when it is interfaced with the (La1.8Dy0.2)(Mo2,zWz)O9 electrolyte. The resistance and chemical capacitance of a low-frequency arc are extracted from the impedance results to evaluate its catalytic activity in oxygen reduction reaction (ORR). (La0.75Ca0.25)(Co0.8Fe0.2)O3 cathode exhibits the minimum area-specific resistance of 0.9 , cm2 and maximum capacitance of 5.7 mF/cm2 at 800°C among the compositions of x=0.1,0.9 and y=0.25. As the Co content increases, the decrease in resistance outweighs the increase in capacitance so that the product of resistance and capacitance (RC time constant) decreases. In contrast, when varying the Ca content of the A-site, the changes in resistance and the capacitance compensate each other; hence the RC time constant is virtually unchanged with respect to the calcium content. Thus, Co is a more influential element than Ca on the ORR catalytic activity. The pore structure study reveals a small amount of Mo diffuses from the electrolyte into the cathode, and its quantity is reduced when interfaced to an electrolyte of high W content. [source] Synthesis of Random Copolymers Poly (methylmethacrylate- co -azo monomer) by ATRP-AGETMACROMOLECULAR SYMPOSIA, Issue 1 2009M.A. Nájera Abstract The synthesis of the azo molecule 1-(2-(4-nitrophenyl) diazenyl) naphtalen-2-ol which has been functionalized with a methacryloxyl fraction is now reported. This azo monomer was copolymerized with methyl methacrylate (MMA) by ATRP where the active species is prepared "in situ" after the reduction reaction of the metal complex Cu (II) - HMTETA by tin 2-ethylhexanoate in 2-butanone as solvent. Experimental conditions for the controlled homopolymerization of MMA were established. By adjusting the amount of reducing agent, a good correlation between theoretical and experimental molecular weight was obtained. Such conditions were also employed for the random copolymerization of MMA with the synthesized azo monomer. [source] Efficient fuel cell catalysts emerging from organometallic chemistryAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 4 2010Helmut Bönnemann Abstract During the last few decades organometallic methodologies have generated a number of highly effective electrocatalyst systems based on mono- and bimetallic nanosparticles having controlled size, composition and structure. In this microreview we summarize our results in fuel cell catalyst preparation applying triorganohydroborate chemistry, ,reductive particle stabilization' using organoaluminum compounds, and the controlled decomposition of organometallic complexes. The advantages of organometallic catalyst preparation pathways are exemplified with RuPt nanoparticles@C as promising anode catalysts to be used in direct methanol oxidation fuel cells (DMFC) or in polymer electrolyte fuel cells (PEMFC) running with CO-contaminated H2 as the feed. Recent findings with highly efficient PtCo3@C fuel cell catalysts applied for the oxygen reduction reaction (ORR) and with the effect of Se-doping on Ru@C ORR catalysts clearly demonstrate the benefits of organometallic catalyst synthesis. Copyright © 2010 John Wiley & Sons, Ltd. [source] Ethanol-tolerant Pt-alloy cathodes for direct ethanol fuel cell (DEFC) applicationsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2009F. J. Rodríguez Varela Abstract The electroactivity of Pt1Co1(a/o)/C and Pt3Cr1(a/o)/C for the oxygen reduction reaction (ORR) in ethanol-containing medium was studied. It was found that these cathodes present a high tolerance to this alcohol. The onset potential of the ORR decreased at 14 and 12 mV in the presence of 0.5 M ethanol on Pt1Co1/C and Pt3Cr1/C, respectively. The tolerance of the Pt alloys is one order of magnitude higher than that shown by Pt-alone catalysts in previous works. Exceptionally, the Pt1Co1/C alloy maintained a very important electrocatalytic activity, i.e. a very small variation in current density at 400 mV in electrochemical cell measurements and improved performances in a direct ethanol fuel cell (DEFC). The current densities obtained from the DEFC equipped with a 10% Pt1Co1/C cathode were similar to those obtained when 20% Pt3Cr1/C was used. However, a higher performance in terms of Pt content was shown by PtCo/C. These electrochemical characteristics indicate the advantage of using PtCo alloys as cathodes in DEFCs. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Structure of CDP- d -glucose 4,6-dehydratase from Salmonella typhi complexed with CDP- d -xyloseACTA CRYSTALLOGRAPHICA SECTION D, Issue 4 2005Nicole M. Koropatkin Tyvelose is a unique 3,6-dideoxyhexose found in the O antigens of some pathogenic species of Yersinia and Salmonella. It is produced via a complex biochemical pathway that employs CDP- d -glucose as the starting ligand. CDP- d -glucose 4,6-dehydratase catalyzes the first irreversible step in the synthesis of this 3,6-dideoxysugar by converting CDP- d -glucose to CDP-4-keto-6-deoxyglucose via an NAD+ -dependent intramolecular oxidation,reduction reaction. Here, the cloning, protein purification and X-ray crystallographic analysis of CDP- d -glucose 4,6-dehydratase from Salmonella typhi complexed with the substrate analog CDP- d -xylose are described. Each subunit of the tetrameric enzyme folds into two domains. The N-terminal region contains a Rossmann fold and provides the platform for NAD(H) binding. The C-terminal motif is primarily composed of ,-helices and houses the binding pocket for the CDP portion of the CDP- d -xylose ligand. The xylose moiety extends into the active-site cleft that is located between the two domains. Key residues involved in anchoring the sugar group to the protein include Ser134, Tyr159, Asn197 and Arg208. Strikingly, Ser134,O, and Tyr159,O, sit within 2.9,Å of the 4,-hydroxyl group of xylose. Additionally, the side chains of Asp135 and Lys136 are located at 3.5 and 3.2,Å, respectively, from C-5 of xylose. In the structurally related dTDP- d -glucose 4,6-dehydratase, the Asp/Lys pair is replaced with an Asp/Glu couple. On the basis of this investigation, it can be speculated that Tyr159 serves as the catalytic base to abstract the 4,-hydroxyl proton from the sugar and that Asp135 and Lys136 play critical roles in the subsequent dehydration step that leads to the final product. [source] Highly Efficient Visible Light Plasmonic Photocatalyst Ag@Ag(Br,I)CHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2010Peng Wang Abstract The new plasmonic photocatalyst Ag@Ag(Br,I) was synthesized by the ion-exchange process between the silver bromide and potassium iodide, then by reducing some Ag+ ions in the surface region of Ag(Br,I) particles to Ag0 species. Ag nanoparticles are formed from Ag(Br,I) by the light-induced chemical reduction reaction. The Ag@Ag(Br,I) particles have irregular shapes with their sizes varying from 83,nm to 1,,m. The as-grown plasmonic photocatalyst shows strong absorption in the visible light region because of the plasmon resonance of Ag nanoparticles. The ability of this compound to reduce CrVI under visible light was compared with those of other reference photocatalyst. The plasmonic photocatalyst is shown to be highly efficient under visible light. The stability of the photocatalyst was examined by X-ray diffraction and X-ray photoelectron spectroscopy. The XRD pattern and XPS spectra prove the stability of the plasmonic photocatalyst Ag@Ag(Br,I). [source] Synthesis of Highly Efficient Ag@AgCl Plasmonic Photocatalysts with Various StructuresCHEMISTRY - A EUROPEAN JOURNAL, Issue 2 2010Peng Wang Abstract By means of a simple ion-exchange process (using different precursors) and a light-induced chemical reduction reaction, highly efficient Ag@AgCl plasmonic photocatalysts with various self-assembled structures,including microrods, irregular balls, and hollow spheres,have been fabricated. All the obtained Ag@AgCl catalysts were characterized by means of X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and UV-visible diffuse reflectance spectroscopy. The effect of the different morphologies on the properties of the photocatalysts was studied. The average content of elemental Ag in Ag@AgCl was found to be about 3.2,mol,%. All the catalysts show strong absorption in the visible-light region. The obtained Ag@AgCl samples exhibit enhanced photocatalytic activity for the degradation of organic contaminants under visible-light irradiation. The stability of the plasmonic photocatalysts was also investigated in detail. [source] Oxygen Reduction Reaction at Three-Phase Interfaces,CHEMPHYSCHEM, Issue 13 2010Dr. Ram Subbaraman Abstract The kinetics of the oxygen reduction reaction (ORR) is studied at metal,supporting electrolyte,Nafion three-phase interfaces. We first demonstrate that the sulfonate anions of Nafion are specifically adsorbed on a wide range of surfaces ranging from Pt(hkl) single-crystal surfaces, Pt-poly, Pt-skin [produced on a Pt3Ni(111) surface by annealing in ultrahigh vacuum, UHV] to high-surface-area nanostructured thin-film (NSTF) catalysts. The surface coverage by sulfonate and the strength of the Pt,sulfonate interaction are strongly dependent on the geometry and the nature of the Pt surface atoms. Also, they are found to behave analogous to (bi)sulfate anion-specific adsorption on these surfaces, where for the Pt(hkl) surfaces, the trend is Pt(111)>Pt(110)>Pt(100) and for the Pt-skin surface on Pt3Ni(111), the interaction strength is found to be Pt-skin The potential for abiotic organic synthesis and biosynthesis at seafloor hydrothermal systemsGEOFLUIDS (ELECTRONIC), Issue 1-2 2010E. SHOCK Geofluids (2010) 10, 161,192 Abstract Calculations are presented of the extent to which chemical disequilibria are generated when submarine hydrothermal fluids mix with sea water. These calculations involve quantifying the chemical affinity for individual reactions by comparing equilibrium compositions with the compositions of mixtures in which oxidation,reduction reactions are inhibited. The oxidation,reduction reactions that depart from equilibrium in these systems provide energy for chemotrophic microbial metabolism. Methanogenesis is an example of this phenomenon, in which the combination of carbon dioxide, hydrogen and methane induced by fluid mixing is far from equilibrium, which can be approached if more methane is generated. Similarly, the production of other organic compounds is also favorable under the same conditions that permit methanogenesis. Alkanes, alkenes, alcohols, aldehydes, carboxylic acids and amino acids are among the compounds that, if formed, would lower the energetic state of the chemical composition generated in mixed fluids. The resulting positive values of chemical affinity correspond to the thermodynamic drive required for abiotic organic synthesis. It is also possible that energy release accompanies biosynthesis by chemotrophic organisms. In this way, hydrothermal ecosystems differ radically from familiar ecosystems at Earth's surface. If captured, the energy released may be sufficient to drive biosynthesis of carbohydrates, purines, pyrimidines and other compounds which require energy inputs. [source] Electrocatalysts: Facile Construction of Pt,Co/CNx Nanotube Electrocatalysts and Their Application to the Oxygen Reduction Reaction (Adv. Mater.ADVANCED MATERIALS, Issue 48 200948/2009) Pt,Co alloyed nanoparticles can be facilely immobilized onto CNx nanotubes due to the incorporated nitrogen, report Yanwen Ma, Zheng Hu, and co-workers on p. 4953. The as-prepared electrocatalysts exhibit good performance for oxygen reduction reactions in acidic media arising from the high dispersion and alloying effect of Pt,Co nanoparticles, as well as the intrinsic catalytic capacity of CNx nanotubes, which is significant for the development of fuel cells. [source] Nicotinamide , biologic actions of an emerging cosmetic ingredientINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 5 2005N. Otte Synopsis Nicotinamide, the water-soluble amide of nicotinic acid, is a component of the two most important coenzymes , nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate. Thus nicotinamide is involved in numerous oxidation,reduction reactions in mammalian biological systems. Nicotinamide essentially acts as an antioxidant. Most effects are exerted via poly-adenosine diphosphate-ribose polymerase inhibition. Thus nicotinamide increasingly gains interest in the prevention and treatment of several skin diseases. It is well established in the systemic therapy of pellagra, a deficiency disease linked to nicotinic acid, but with respect to topical use there is still a need for further evidence with respect to its manifold potential uses. Currently, its local use is established in the care of acne-prone skin. Résumé Le nicotinamide, l,amide hydrosoluble de l'acide nicotinique est un composant des deux plus importants co-enzymes NAD et NADP. Le nicotinamide est impliqué dans de nombreuses réactions d'oxydo-réduction dans les systèmes biologiques des mammifères. Le nicotinamide agit essentiellement en tant qu'anti-oxydant. La plupart des effets sont exercés via l'inhibition de la poly (ADP-ribose) polymerase (PARP). Ainsi, l'intérêt du nicotinamide croît dans la prévention et le traitement de nombreuses maladies cutanées. Son rôle est bien établi dans la thérapie systémique de la pellagre, une maladie déficiente liée à l'acide nicotinique, mais en ce qui concerne son utilisation topique, du fait de ses multiples applications potentielles, il est encore nécessaire d'accumuler davantage de preuves. Son utilisation locale est couramment admise dans le traitement des peaux sujettes à l'acné. [source]
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