Rotating disk electrode catalyst

Fig. 3. Steady state concentration profiles of catalyst and substrate species in the film and diffusion layer for for various cases of redox catalysis at polymer-modified electrodes. Explanation of layers see bottom case (S + E) f film d diffusion layer b bulk solution i, limiting current at the rotating disk electrode other symbols have the same meaning as in Fig. 2 (from ref.

Figure 8.9 Polarization curves for a PtSn/C catalyst recorded by a rotating disk electrode in 0.5 M H2SO4 saturated with either pure hydrogen, a H2/2% CO mixture, and pure CO (the arrow points to the onset of CO oxidation) at 60 °C with 1 mV/s and 2500 rev/min the dashed curve is the cyclic voltammogram (in arbitrary units) in an argon-purged solution at 60 °C with 50 mV/s. (Reprinted with permission from Aienz etal. [2005]. Copyright 2005. Elsevier.)...

Schmidt TJ, Gasteiger HA, Behm RJ. 1999b. Rotating disk electrode measurements on a high-surface area Pt/Vulcan carbon fuel cell catalyst. J Electrochem Soc 146 1296-1304. 

Thin catalyst layers on a GC rotating disk electrode (RDE) or a rotating ring-disk electrode (RRDE) serve for studies of ORR kinetics. In order to separate the kinetic current from the measured current j, Schmidt and co-workers [Schmidt et al., 1998b] corrected the latter for the influence of oxygen diffusion in the aqueous electrolyte and in the polymer film using the foUowing equation ... 

In the most common approach, a water-insoluble metaUoporphyrin is deposited on the surface of a rotating disk electrode (RDE) or on the disk of a rotating ring-disk electrode (RRDE Fig. 18.7a) as a film of poorly defined morphology, either by spontaneous adsorption from a solution of the catalyst in an organic solvent or by evaporation of an aliquot of such a solution onto the electrode. It is impossible to know the... 

If a reaction path is predominant and one of its elementary step is rate determining, the Tafel slope will be characteristic of this step. Thus, electrochemical measurements performed on rotating disk electrode can provide a first solution to elucidate the mechanistic behavior of oxygen reduction reaction on a catalyst. Par-sons has demonstrated that, in a several step electrode process,... 

Continue evaluation of Pt catalysts being synthesized using the colloidal sol, carbothermal and the electrodeposition techniques and compare results against catalyst screening specifications. Debug rotating disk electrode technique. 

UTCFC has modified the carbothermal synthesis process (U.S. Patent 4,677,092, US 4,806,515, US 5,013,618, US 4,880,711, US 4,373,014, etc.) to prepare 40 wt% ternary Pt alloy catalysts. Various high-concentration Pt catalyst systems were synthesized and the electrochemical surface area (EGA) and electrochemical activity values compared to commercially available catalysts (see Table 3). The UTCFC catalysts showed EGA and activity values comparable to the commercial catalysts. A rotating disk electrode technique for catalyst activity measurements has been developed and is currently being debugged at UTCFC. 

The catalytic activity of the catalysts for the ORR is screened using a rotating-disk electrode (RDF) method. The activity of the new transition metal oxide catalysts is estimated by comparison to a standard RDE of 10 weight % platinumWulcan carbon, XC-72 (PtWC) catalyst (Alfa). The electrocatalytic activity of the catalysts are compared in Tafel plots of potential vs. current, calculated from the electrochemical data as described in the literature. 

Determine the catalytic properties of the new catalyst for hydrogen (H2) and H2 + CO oxidation and improve the thin layer rotating disk electrode method. 

Electrocatalysts with a 1/8 of monolayer Pt loading on Ru nanoparticles have been synthesized by spontaneous deposition of Pt on a Ru surface, each of which have at least three times larger mass-specific activity for H2 oxidation than two commercial catalysts and a larger CO tolerance, as determined by thin film rotating disk electrode measurements. 

The thin-film rotating disk electrode has been used for determination of the catalytic activity. The catalyst was attached to the glassy carbon electrode by careful deposition from aqueous dispersion and no Nafion film was used to cover the deposit. This can significantly improve the tests of supported electrocatalysts. Kinetic parameters for the oxidation of H2 and H2 + CO have been determined by... 

For non-noble metal ORR catalysts, the definition of catalytic activity is different from that of Pt-based catalysts. For a nonnoble metal catalyst, the similar preparation procedure for CL and ORR measurement steps using rotating disk electrode technique to that for Pt-based catalyst have been widely used in literature. However, due to both the ORR onset and half-wave potentials catalyzed by non-noble metal catalysts are much lower than those of Pt-based catalysts, it is difficult or impossible to observed ORR current density at 0.9 V vs RHE. A current density at other lower potentials may be used to define the catalyst activity for the purpose of comparison. In this case, Eqn (3.7) may still usable except the electrode potential is not 0.9 V, instead of... 

In Chapter 5, we presented rotating disk electrode (RDE) technique in terms of both fundamentals and applications in catalyst evaluation for oxygen reduction reaction (ORR) kinetics. 

The electrocatalytic activity of ORR on chalcogenides has been performed under hydrodynamic and temperature conditions using the rotating disk electrode (RDE) technique. We recall that dispersed catalysts either as non-supported or as supported on carbon have been prior prepared in form of inks, which are ahqnoted onto a well geometrically defined substrate, such as glassy caibon and/or gold disks. ... 

Cyclic voltammetry (CV), rotating disk electrode (RDE), and rotating ring-disk electrode (RRDE) in a traditional tri-electrode cell are often employed in the study of the ORR kinetics and mechanisms on various catalysts in liquid electrolytes [27, 28]. As shown in Fig. 15.2, a tri-electrode cell contains a working electrode (WE), a reference electrode (RE), and a counter electrode (CE). The CE has much... 

The transition to more realistic conditions, near fuel cell environment, is achieved using a thin-film rotating disk electrode with a practical supported catalyst. It allows obtaining kinetic parameters such as the the exchange current density and Tafel slopes, avoiding the use of complex models. This is of fundamental importance, because small catalyst particles having a significant fraction of surface atoms could behave differently compared to bulk materials. 

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