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Electrocatalytic surface

Garcia-Araez N, Climent V, Feliu JM. 2008. Evidence of water reorientation on model electrocatalytic surfaces from nanosecond-laser-pulsed experiments. J Am Chem Soc 130 3824-3833. [Pg.241]

W.B. Nowall and W.G. Kuhr, Detection of hydrogen peroxide and other molecules of biological importance at an electrocatalytic surface on a carbon fiber microelectrode. Electroanalysis 9, 102-109 (1997). [Pg.458]

Electrochemical Reaction/Transport. Electrochemical reactions occur at the electrode/electrolyte interface when gas is brought to the electrode surface using a small pump. Gas diffuses through the electrode structure to the electrode/electrolyte interface, where it is electrochemically reacted. Some parasitic chemical reactions can also occur on the electrocatalytic surface between the reactant gas and air. To achieve maximum response and reproducibility, the chemical combination must be minimized and controlled by proper selection of catalyst sensor potential and cell configuration. For CO, water is required to complete the anodic reaction at the sensing electrode according to the following reaction ... [Pg.554]

With a basic mechanism at hand, a rational approach for designing catalysts with desired properties becomes possible. However, despite progress in the direct observation of surface intermediates using high pressure, realistic in situ spectroscopic methods and deeper insight into basic reaction processes, the capability of rationally designing an electrocatalytic surface with a set of desired properties has not yet fully been achieved. [Pg.419]

The ORR mechanism is very complex and involves a number of different adsorbate intermediates. In addition to its complex reduction mechanism, the relatively high thermodynamic electrode potential of the ORR causes electrocatalytic surfaces... [Pg.420]

In this mechanism, the electron transfer occurs during the regeneration step of the electrocatalytic surface ... [Pg.466]

It is often claimed that electrocatalysts in fuel cells are dependent on the exchange current density, i0 of the slowest reaction in the cell, (a) Make Tafel plots for i0 = 10 I,10 6, and 10-3 A cm-2 and bTaM = 0.12. (b) Then draw plots of the same type and the same i0, but with b values of 0.12, 0.05, 0.038, and 0.029 (T = 298 K). (c) Write out your conclusions concerning the interplay of /0 and b in the Tafel relation (B = RT/aF). (d) How does this relate to the choice of electrocatalytic surfaces for optimal fuel cell performance (Bockris)... [Pg.381]

The results presented above show that the poly(aniline)/poly(vinylsul-fonate) composite is an electrocatalytic surface for NADH oxidation at... [Pg.70]

It was shown in Section 2.3.4.3 that poly(aniline)/poly(vinylsulfonate) films are also electrocatalytic surfaces for the oxidation NADPH. Assuming that the kinetics of this system are similar to those for the NADH system, the data have been analysed using the uninhibited kinetic model. From comparison to the NADH data, this film is thick (e > 1) and the data span both Cases II and IV. Therefore, all the data were fitted using the expression for the Case II/IV boundary (equation (2.21) Table 2.4) using equation (2.4) to calculate the concentration of NAD(P)H at the film/solution interface. The fit is shown in Fig. 2.30 and the parameters generated by this fit are given in Table 2.9. [Pg.82]

Electrodes may also be modified by deposition of metal adatoms at potentials several hundred millivolts positive to the reversible potential for metal deposition. A submonolayer of adatoms may lower overpotentials for electron transfer processes or improve the selectivity of an electrocatalytic surface. Underpotential deposition and electrocatalysis have been discussed in a review [182]. [Pg.246]

The nature of O adatoms on noble metals, which frequently form islands on the electrocatalytic surface (Fig. 40), has been studied in detail and imaged by scanning tunneling microscopy (STM), by Ertl and coworkers [140], Some of the best binary and tertiary alloy electrocatalysts developed so far for the ORR reaction are compared in Fig. 41 [141]. [Pg.63]

In view of this need, we discuss here a variety of electrocatalytic topics, ranging from basic and microscopic concepts to phenomenological principles. Thus, the origin of electrodic reactions, electrosorption, and electrode kinetics are introduced briefly for the benefit of the nonelectrochemist. Since electrocatalytic reactions take place at the electrode surface, attention is given to recent efforts to link catalyst activity with microscopic surface properties. These include surface crystallographic orientation, crystallite size and distribution, adsorbate-adsorbent-support synergism, multiple adsorption states, identification of surface intermediates, and electrocatalytic surface reaction mechanisms. [Pg.219]

Electrocatalytic surface reactions may involve convective or diffusive transport of reactants and products external to the electrode surface or in the porous structure. If the rate of mass transport is comparable to or slower than the surface rate, the electrode kinetic and selectivity behavior will be altered (48a, 60-62, 407). [Pg.312]

Adsorption of more than one species and complex electrocatalytic surface reactions [Eqs. (10) and (16)] may result in nonunique steady-state operation and in current or potential oscillations (31, 78, 417). We examined recently conditions for isothermal multiple steady states at planar, and porous, flow-by or flow-through electrocatalysts (418). [Pg.320]

The difference in behavior of pyrolytic graphite, examined in Ref. 2, and the glassy carbon investigated in this more recent work, is probably done to the different electrocatalytic surfaces that these materials present. Thus, impedance measurements we have made indicate little adsorption pseudocapacitance for adsorbed Br species at glassy carbon whereas, at pyrolytic graphite, an adsorption capacitance is measurable. The results depend on edge or basal-plane exposure. [Pg.128]

Coupled reactions of two or more enzymes can also be used to minimize interference, as well as to amplify the response and extend the scope of the enzyme electrode towards additional analytes. For example, peroxidases can be coupled with oxidases to allow low-potential detection of the liberated peroxide. Electrocatalytic surfaces, particularly those based on metallized carbon, represent a new and effective approach for minimizing electroactive interference [9]. Such strategy relies on the preferential electrocatalytic detection of the liberated peroxide or NADH species at rhodium or ruthenium dispersed carbon bioelectrodes. [Pg.137]

Electrochemical sensor fabrication has dominated the analytical application of polymers. In some sensors the polymer film acts as a membrane for the preconcentration of ions or elements before electrochemical detection. Polymers also serve as materials for electrode modification that lower the potential for detecting analytes. In addition, some polymer films function as electrocatalytic surfaces. Using a polymer in biosensors is a very rapidly developing area of electroanalytical chemistry. Polymeric matrix modifiers have been applied as diffusional barriers in constructing not only sensitive amperometric biosensors, but also electrochemical sensors that apply potentiometric, conductimetric, optical, and gas-sensing transducer systems. The principles, operations, and application of potentiometric, conductimetric, optical and gas sensors are described in Refs. 13, 39-41. In this chapter, we focus mainly on amperometric biosensors based on redox enzymes. [Pg.300]

P. McGrath, A.M. Fojas, B. Rush, J.A. Reimer, E.J. Cairns, Characterizing electrocatalytic surfaces electrochemical and NMR studies of methanol and carbon monoxide on Pt/C, Electrochim. Acta 53 (2007) 1365-1371. [Pg.212]

Chen C, Kang Y, Huo Z, Zhu Z, Huang W, Xin HL, Snyder JD, Li D, Herron JA, Mavrikakis M, Chi M, More KL, Li Y, Markovic NM, Somoijai GA, Yang P, Stamenkovic VR (2014) Highly crystalline multimetalhc nanoframes with three-dimensional electrocatalytic surfaces. Science 343 1339-1343... [Pg.95]

In this chapter, connections will be established between electrocatalytic surface phenomena and porous media concepts. The underlying logics appear simple, at least at first sight. Externally provided thermodynamic conditions, operating parameters, and transport processes in porous composite electrodes determine spatial distributions of reaction conditions in the medium, specifically, reactant and potential distributions. Local reaction conditions in turn determine the rates of surface processes at the catalyst. This results in an effective reactant conversion rate of the catalytic medium for a given electrode potential. [Pg.163]


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See also in sourсe #XX -- [ Pg.22 ]

See also in sourсe #XX -- [ Pg.22 ]




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Approximate Kinetic Expressions for Electrocatalytic Reactions on Heterogeneous Surfaces

Electrocatalytic Activity of Semiconductor Electrodes Modified by Surface-Deposited Metal Nanophase

Electrocatalytic activity active surface area

Electrocatalytically active surface area

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