Electrocatalysis effects

Structural Effects on Electrocatalysis Effect of Particle Size... 

EC mechanism, 34, 42, 113 E. Coli, 186 Edge effect, 129 Edge orientation, 114 Electrical communication, 178 Electrical double layer, 18, 19 Electrical wiring, 178 Electrocapillary, 22 Electrocatalysis, 121 Electrochemical quartz crystal, microbalance, 52 Electrochemihuiiinescence, 44 Electrodes, 1, 107... 

Small-Particle Effects and Structural Considerations for Electrocatalysis Kinoshita, K. 14... 

In the case of electrochemically promoted (NEMCA) catalysts we concentrate on the adsorption on the gas-exposed electrode surface and not at the three-phase-boundaries (tpb). The surface area, Ntpb, of the three-phase-boundaries is usually at least a factor of 100 smaller than the gas-exposed catalyst-electrode surface area Nq. Adsorption at the tpb plays an important role in the electrocatalysis at the tpb, which can affect indirectly the NEMCA behaviour of the electrode. But it contributes little directly to the measured catalytic rate and thus can be neglected. Its effect is built in UWr and [Pg.306]

The reason is that the backspillover ions desorb to the gas phase directly from the three-phase-boundaries or react directly at the three-phase-boundaries (electrocatalysis, A=l) before they can migrate on the gas-exposed electrode surface and promote the catalytic reaction. The limits of NEMCA are set by the limits of stability of the effective double layer at the metal/gas interface. 

Effective core potential, 269 Effective double layer characterization of, 189 isotherm, 306, 315 kinetic expressions, 316 observations of with STM, 259 stability of, 225, 351, 503 Effectiveness factor of promotion computation of, 505 definition of, 505 Electrocatalysis... 

A period of high research activity in electrocatalysis began after it had been shown in 1963 that fundamentally, an electrochemical oxidation of hydrocarbon fuel can be realized at temperatures below 150°C. This work produced a number of important advances. They include the discovery of synergistic effects in platinum-ruthenium catalysts used for the electrochemical oxidation of methanol. 

At present, most workers hold a more realistic view of the promises and difficulties of work in electrocatalysis. Starting in the 1980s, new lines of research into the state of catalyst surfaces and into the adsorption of reactants and foreign species on these surfaces have been developed. Techniques have been developed that can be used for studies at the atomic and molecular level. These techniques include the tunneling microscope, versions of Fourier transform infrared spectroscopy and of photoelectron spectroscopy, differential electrochemical mass spectroscopy, and others. The broad application of these techniques has considerably improved our understanding of the mechanism of catalytic effects in electrochemical reactions. 

Kinoshita, K., Small-particle effects and structural considerations for electrocatalysis, in Modem Aspects of Electrochemistry, 1. O M. Bockris, Eds., Vol. 14, Kluwer, New York, 1982, p. 557. 

With the four-electron ORR process in the fuel cell cathode well recognized as the principal challenge at both the theoretical and experiniental/technical levels, it is interesting to examine the effects of the most recent theoretical developments on the fundamental understanding of ORR electrocatalysis. Such examination would naturally focus on the nature and quahty of the links with experimental work, as reflected by ... 

Adzic RR, Tripkovic AV, O Grady W. 1982. Structural effects in electrocatalysis. Nature 296 137. 

Chang SC, Leung LWH, Weaver MJ. 1990. Metal crystallinity effects in electrocatalysis as prohed hy real-time ETIR spectroscopy electrooxidation of formic acid, methanol, and ethanol on ordered low-index platinum surfaces. J Phys Chem 94 6013-6021. 

Lamy C, Leger JM, Claviher J, Parsons R. 1983. Structural effects in electrocatalysis A comparative study of the oxidation of CO, HCOOH and CH3OH on single crystal Pt electrodes. J Electroanal Chem 150 71-77. 

I,eiva E, Iwasita T, Hertero E, FeUu JM. 1997. Effect of adatoms in the electrocatalysis of HCOOH oxidation. A theoretical model. Langmuir 13 6287 6293. 

It has been often stressed that low eoordinated atoms (defeets, steps, and kink sites) play an important role in surfaee ehemistry. The existenee of dangling bonds makes steps and kinks espeeially reaetive, favoring the adsorption of intermediate species on these sites. Moreover, smdies of single-crystal surfaces with a eomplex geometry have been demonstrated very valuable to link the gap between fundamental studies of the basal planes [Pt( 111), Pt( 100), and Pt(l 10)] and applied studies of nanoparticle eatalysts and polycrystalline materials. In this context, it is relevant to mention results obtained with adatom-modified Pt stepped surfaces, prior to discussing the effect of adatom modification on electrocatalysis. 

The good coincidence between the model and the experimental data depicted in Fig. 7.14 supports the idea that this model captures the essential aspects of the effect of different adatoms on the electrocatalysis of formic acid oxidation. 

Gasteiger HA, Markovic NM, Ross PN Jr. 1996. Structural effects in electrocatalysis Electrooxidation of carbon monoxide on Pt3Sn single-crystal surfaces. Catal Lett 36 1-8. 

Stamenkovic V, Schmidt TJ, Markovic NM, Ross PN Jr. 2002. Surface composition effects in electrocatalysis Kinetics of oxygen reaction on well defined PtsNi and PtsCo alloy surfaces. J Phys Chem B 106 11970-11979. 

Schmidt TJ, Stamenkovic V, Arenz M, Markovic NM, Ross PN. 2002. Oxygen electrocatalysis in alkaline electrolyte VtQikl), AuQikl) and the effect of Pd-modification. Electrochim Acta 47 3765-3776. 

Mukeijee S, McBreen J. 1989. Effect of particle size on the electrocatalysis by carbon-supported Pt electrocatalysts an in situ XAS investigation. J Electroanal Chem 448 163-171. 

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