Electrocatalytic Electrodes

Trollund E, Ardiles P, Aguirre M J, Biaggio SR, Rocha-Filho RC (2000) Spectroelectrochemical and electrical characterization of poly(cobalt-tetra aminophthalocyanine)-modified electrodes electrocatalytic oxidation of hydrazine. Polyhedron 19(22-23) 2303-2312... 

Electrode — Electrocatalytic electrode — Figure. Plots of the exchange current density of the hydrogen electrode reaction (left) as a function of the enthalpy of the metal-hydrogen bond and the current density of the electrochemical oxidation of ethylene as a function of the enthalpy of sublimation of various metals and alloys (right). These displays are also called Volcano plots... 

Cataldi, T.R.L, Guerrieri, A., Casella, LG., and Desimoni, E. 1995. Study of a cobalt-based surface modified glassy carbon electrode Electrocatalytic oxidation of sugars and alditols. Electroanalysis 7, 305-311. 

Pd, and Ru electrodes. Electrocatalytic hydrogenation of acetone, acetaldehyde, and acetophenone on platinized Pt in acidic solution produces the eorresponding hydrocarbons, whereas in alkaline media, alcohols or dimers are obtained. Phenol may be reduced to cyclohexanol on Pt in acidic solutions. Pt deposited or supported on ear-bon is more active than platinized Pt. However, the highest yield was observed on Rh/... 

Spectroelectrochemical and electrical characterization of poly(cobalt-tetraaminophthalocyanine)-modified electrodes Electrocatalytic oxidation of hydrazine. Polyhedmn 19, 2303-2312. 

Tse Y, Janan P, Lam H, Zhang J, Pietro W, Lever A. Monomeric and polymeric tetra-aminophthalocyanatocobalt(ll) modified electrodes electrocatalytic reduction of oxygen. J Porphyrins Phthalocyanines 1997 01(01) 3—16. 

CyrA,HuotP,BelotG, Lessard J (1990) The efficient electrochemical reduction of nitrobenzene and azoxybenzene to aniline in neutral and basic aqueous methanolic solutions at Devarda copper and Raney nickel electrodes electrocatalytic hydrogenolysis of N-O and N-N bonds. Electrochim Acta 35 147-152... 

As indicated by the terminology of fuel cells, e.g., PEFC, AFC, SOFC, others (see below), the electrolyte is the decisive cell component, which determines operation temperature, the choice the electrodes (electrocatalytic materials), and finally the specifics of the electrochemistry of the reactants. This, on the other hand, has consequences for the layout of the fuel cell design (balance of plant) and possible applications of the respective fuel cell technology, according to the required duty cycle of the application. 

Ozoemena KI, Nkosi D, Pillay J (2008) Influence of solution pH on the electron transport of the self-assembled nanoarrays of single-walled carbon nanotube-cobalt tetra-aminophthalocyanine on gold electrodes electrocatalytic detection of epinephrine. 

In acid electrolytes, carbon is a poor electrocatalyst for oxygen evolution at potentials where carbon corrosion occurs. However, in alkaline electrolytes carbon is sufficiently electrocatalytically active for oxygen evolution to occur simultaneously with carbon corrosion at potentials corresponding to charge conditions for a bifunctional air electrode in metal/air batteries. In this situation, oxygen evolution is the dominant anodic reaction, thus complicating the measurement of carbon corrosion. Ross and co-workers [30] developed experimental techniques to overcome this difficulty. Their results with acetylene black in 30 wt% KOH showed that substantial amounts of CO in addition to C02 (carbonate species) and 02, are... 

S.3.3 Electrocatalytic Modified Electrodes Often the desired redox reaction at the bare electrode involves slow electron-transfer kinetics and therefore occurs at an appreciable rate only at potentials substantially higher than its thermodynamic redox potential. Such reactions can be catalyzed by attaching to the surface a suitable electron transfer mediator (45,46). Knowledge of homogeneous solution kinetics is often used to select the surface-bound catalyst. The function of the mediator is to facilitate the charge transfer between the analyte and the electrode. In most cases the mediated reaction sequence (e.g., for a reduction process) can be described by... 

Like other ion-exchange polymers, conducting polymers have been used to immobilize electroactive ions at electrode surfaces. Often the goal is electrocatalysis, and conducting polymers have the potential advantage of providing a fast mechanism for electron transport to and from the electrocatalytic ions. 

Beden, B. Electrocatalytic Oxidation of Oxygenated Aliphatic Organic Compounds at Noble Metal Electrodes 22... 

The experimental setup is depicted schematically in Figure 1.2. Upon varying the potential of the catalyst/working electrode the cell current, I, is also varied. The latter is related to the electrocatalytic (net-charge transfer) reaction rate re via re=I/nF, as well known from Faraday s law. The electrocatalytic reactions taking place at the catalyst/solid electrolyte/gas three-phase-boundaries (tpb), are ... 

Wagner was first to propose the use of solid electrolytes to measure in situ the thermodynamic activity of oxygen on metal catalysts.17 This led to the technique of solid electrolyte potentiometry.18 Huggins, Mason and Giir were the first to use solid electrolyte cells to carry out electrocatalytic reactions such as NO decomposition.19,20 The use of solid electrolyte cells for chemical cogeneration , that is, for the simultaneous production of electrical power and industrial chemicals, was first demonstrated in 1980.21 The first non-Faradaic enhancement in heterogeneous catalysis was reported in 1981 for the case of ethylene epoxidation on Ag electrodes,2 3 but it was only... 

Solid electrolyte fuel cells have been investigated intensively during the last four decades.10,33 37 Their operating principle is shown schematically in Fig. 3.4. The positive electrode (cathode) acts as an electrocatalyst to promote the electrocatalytic reduction of O2 (g) to O2 ... 

Although several metals, such as Pt and Ag, can also act as electrocatalysts for reaction (3.7) the most efficient electrocatalysts known so far are perovskites such as Lai-xSrxMn03. These materials are mixed conductors, i.e., they exhibit both anionic (O2 ) and electronic conductivity. This, in principle, can extend the electrocatalytically active zone to include not only the three-phase-boundaries but also the entire gas-exposed electrode surface. 

With the exception of H20 electrolysis51,59 it is likely that, for all other electrocatalytic reactions listed on Table 3.2, catalytic phenomena taking place on the gas-exposed electrode surface or also on the solid electrolyte surface, had a certain role in the observed kinetic behaviour. However, this role cannot be quantified, since the measured increase in reaction rate was, similarly to the case of the reactions listed on Table 3.1, limited by Faraday s law, i.e. ... 

The reference electrode-solid electrolyte interface must also be non-polarizable, so that rapid equilibration is established for the electrocatalytic charge-transfer reaction. Thus it is generally advisable to sinter the counter and reference electrodes at a temperature which is lower than that used for the catalyst film. Porous Pt and Ag films exposed to ambient air have been employed in most previous NEMCA studies.1,19... 

Since electrochemical promotion (NEMCA) studies involve the use of porous metal films which act simultaneously both as a normal catalyst and as a working electrode, it is important to characterize these catalyst-electrodes both from a catalytic and from an electrocatalytic viewpoint. In the former case one would like to know the gas-exposed catalyst surface area A0 (in m2 or in metal mols, for which we use the symbol NG throughout this book) and the value, r0, of the catalytic rate, r, under open-circuit conditions. 

If only the three-phase-boundaries (tpb) were electrocatalytically active one would expect Cd values of the order of 10 pF/cm2. The thus measured high Cd values also provide evidence that the charge transfer zone is extended over the entire gas-exposed electrode surface, i.e. that an effective double layer is formed over the entire gas exposed electrode surface. 

---