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Oxygen Reduction Reaction (oxygen + reduction_reaction)

Distribution by Scientific Domains

Chemistry	62%
Polymers and Materials Science	37%

Selected Abstracts

Heterogeneous Electron Transfer and Oxygen Reduction Reaction at Nanostructured Iron(II) Phthalocyanine and Its MWCNTs Nanocomposites

ELECTROANALYSIS, Issue 9 2010
Solomon
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 Electrodes

ELECTROANALYSIS, Issue 13-14 2004
Gautam 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 Reaction

FUEL CELLS, Issue 4 2010
W. 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 2009
N. 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 2009
48/2009)
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 Reaction

ADVANCED MATERIALS, Issue 48 2009
Shujuan 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]

Oxygen Reduction Reaction at Three-Phase Interfaces,

CHEMPHYSCHEM, Issue 13 2010
Dr. 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[source]

Heterogeneous Electron Transfer and Oxygen Reduction Reaction at Nanostructured Iron(II) Phthalocyanine and Its MWCNTs Nanocomposites

Green Synthesis of Silver Nanoparticles Using Ionic Liquid and Application for the Detection of Dissolved Oxygen

ELECTROANALYSIS, Issue 6 2010
Tsung-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]

Synthesis of Nanohole-Structured Single-Crystalline Platinum Nanosheets Using Surfactant-Liquid-Crystals and their Electrochemical Characterization

ADVANCED FUNCTIONAL MATERIALS, Issue 4 2009
Tsuyoshi 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 Reaction

Electrochemical Behavior of Gel-Derived Lanthanum Calcium Cobalt Ferrite Cathode in Contact with LAMOX Electrolyte

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2008
Tsu-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]

Efficient fuel cell catalysts emerging from organometallic chemistry

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 4 2010
Helmut 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) applications

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2009
F. 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]