Electrocatalytic oxidation molecules

Interest in fuel cells has stimulated many investigations into the detailed mechanisms of the electrocatalytic oxidation of small organic molecules such as methanol, formaldehyde, formic acid, etc. The major problem using platinum group metals is the rapid build up of a strongly adsorbed species which efficiently poisons the electrodes. 

Perhaps the most important paradigm in research on the mechanism of the electrocatalytic oxidation of small organic molecules is the dual pathway mechanism introduced in Capon and Parsons [1973a, b], and reviewed in Parsons and VanderNoot [1988]. In terms of methanol oxidation, the dual pathway may be summarized in a simplified way by Fig. 6.1. The idea is that the complete oxidation of methanol to carbon dioxide may follow two different pathways ... 

Sun SG. 1998. Studying electrocatalytic oxidation of small organic molecules with in-situ infrared spectroscopy. In Lipkowski J, Ross PN, eds. Electrocatalalysis. New York Wiley-VCH. p 243-291. 

Leung L-WH, Weaver MJ. 1990. Influence of adsorbed carbon monoxide on the electrocatalytic oxidation of simple organic molecules at platinum and palladium electrodes in acidic solution A survey using real-time FITR spectroscopy. Langmuir 6 323-333. 

This section addresses the role of chemical surface bonding in the electrochemical oxidation of carbon monoxide, CO, formic acid, and methanol as examples of the electrocatalytic oxidation of small organics into C02 and water. The (electro)oxidation of these small Cl organic molecules, in particular CO, is one of the most thoroughly researched reactions to date. Especially formic acid and methanol [130,131] have attracted much interest due to their usefulness as fuels in Polymer Electrolyte Membrane direct liquid fuel cells [132] where liquid carbonaceous fuels are fed directly to the anode catalyst and are electrocatalytically oxidized in the anodic half-cell reaction to C02 and water according to... 

The general scheme for the electrocatalytic oxidation of an organic molecule (CnHxOy) by Ag(II) ions in the form of AgN03 is as follows. 

The electrocatalytic oxidation of ethanol has been investigated for many years on different platinum-based electrodes, including Pt/X alloys (with X = Ru, Sn, Mo, etc ), and dispersed nanocatalysts. Pme platinum smooth electrodes are rapidly poisoned by some strongly adsorbed intermediates, such as carbon monoxide, resulting from the dissociative chemisorption of the molecule, as shown by the first experiments in infrared reflectance spectroscopy (EMIRS). Both kinds of adsorbed CO, either linearly-bonded or bridge-bonded to the platinum surface, are observed. Besides, oth-... 

The electrocatalytic oxidation of many small organic molecules was carried out at Pt-based catalysts dispersed in an ECP, particularly that of Cl molecules (formic acid, formaldehyde, and methanol). 

With the development of fuel cells, electrocatalytic oxidation of small organic molecules, such as methanol or formic acid, has attracted great interest recently (Rice et al., 2003). Ethanol oxidation to acetaldehyde can be performed by means of the reactions ... 

The electrocatalytic oxidation of organic molecules has been studied very extensively using various supports and adatoms. There are several proposed mechanisms in the literature to interpret the role of adatoms. It is assumed, for instance, that adatoms block the poison formation not leaving enough space for these reactions. According to another hypothesis, adatoms act as redox intermediates. Independently from the explanation, it is a fact that very often a significant enhancement of the catalytic activity can be observed and these results could provide very useful information for liquid-phase catalytic reactions.60... 

The electrocatalytic oxidation of small organic molecules at noble metal electrodes has been intensively investigated over a period of many years, both by conventional electrochemical methods [59], including radiotracer measurements, and by an increasing battery of non-conventional techniques. The metal anodes in such reactions are rapidly poisoned by the formation of strongly adsorbed species that block the catalytic surface, and the identification of these species has become a major objective. 

This work aims to improve the selectivity of the electrocatalytic oxidation of sucrose into its monocarboxylic acids without breaking the squeleton of the molecule. 

In the electrocatalytic oxidation of small organic molecules, the chemisorption process is usually dissociative, that is, quite irreversible. However, it is usual to relate Gj to the concentration Ci of a reactive species i in solution and to describe adsorption isotherms in the same way as at the gas/solid interface. Details on the derivation of isotherms and on the different types of isotherms can be found in review papers. The adsorption isotherms most often encountered at the electrode/electrolyte interface are the Langmuir isotherms ... 

H. Laborde, J.M. L6ger and C. Lamy, Electrocatalytic oxidation of methanol and Cl molecules on highly dispersed electrodes Part 1 platinum in polyaniline, J. Appl. Electrochem., 24, 219-226 (1994). 

The electrochemical oxidation of small molecules such as methanol, formaldehyde and formic acid on Pt and Pd electrodes has received considerable attention because of the potential of these molecules as fuels for low temperature fuel cells. Samjeske et al. described the electrocatalytic oxidation of formaldehyde at an electrode made from a 50-nm Pt film deposited on a single-reflection hemicylindrical Si IRE under constant current (galvanostatic) and potential sweep conditions by time-resolved SEIRA spectroscopy." ... 

Lamy C, Leger JM (1991) Electrocatalytic oxidation of small organic molecules at platinum single crystals. J Chim Phys Phys -Chim Biol 88 1649-1671... 

The electrocatalytic oxidation of alkenes has similarly been the subject of extensive study, as part of the development of fuel cell technology. The overall reaction is thought to be similar to gas phase oxidation processes, involving both adsorption of the olefin and oxidative adsorption of water molecules, the latter forming intermediate species which react with the... 

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