Electro-oxidation of small organic molecules

A major focus of more recent studies on adsorption at metal electrodes has been the investigation of the mechanism of electro-oxidation of organic fuels (methanol, formic acid, formaldehyde, etc. [55, 56]) and the electro-reduction of carbon dioxide. The former type of reaction is important in the context of the development of fuel cells a major problem has been the poisoning of the anode by carbon fragments and mechanistic insights are urgently needed. In the latter case, the development of C02 sensors has a high priority. 

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. 

The variation in intensity and widths of the positive and negative peaks centred around 2060 cm-1 were interperted in terms of a potential-dependent shift in band position and energy of linearly adsorbed CsO at constant 

This latter point is an important one in view of the fact that adsorbed hydrogen is almost certainly one of the transient species formed by electrosorption of hydrogen-containing small organic (fuel) molecules, and C02 will also be present in the electrolyte after a few electrochemical measurements. 

The authors conclusions were somewhat tentative with respect to the behaviour of the feature at 1860 cm-1 and perhaps in any detailed treatment of the potential dependence of adsorption. 

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Gasteiger HA, Markovic NM, Ross PN, Caims EJ. 1994. Electro-oxidation of small organic molecules on well-characterized Pt-Ru alloys. Electrochim Acta 39 1825-1832. 

Among the numerous studies concerning the electro-oxidation of small organic molecules, those dealing with methanol are the most common due to the huge potential expected impact from direct methanol fuel cells (DMFC) for various... 

To April 1987, the in-situ IR studies on the electro-oxidation of small organic molecules show that the strongly adsorbed fragments which act as poisons in these reactions are all CO species. There has been no spectroscopic evidence for the presence of COH, even for conditions of less than saturation coverage by (CO)ads. In addition, the adsorbed CO is very stable, requiring fairly high potentials for its oxidation to C02 [55]. The reader is referred to the reviews by Bewick and Pons [55] and Foley et al. [56, 69] and the references cited therein for a more detailed treatment. 

Electro-Oxidation of Small Organic Molecules and Their Application in Fuel Cells... 

Janaina Fernandes Gomes was bom in Sao Carlos (Brazil) in 1978. Ph.D. in Science at the University of Sao Paulo (Brazil) and at the University Paris XI (France) in 2007. She was postdoctoral fellow at the Fritz Haber Institute of the Max Planck Society (Germany) in 2008 and at the Institute of Chemistry of Sao Carlos of the University of Sao Paulo from 2009 to 2013. Her research areas include catalysis and electrocatalysis. Her research activities are mainly concentrated in the electro-oxidation of small organic molecules. She has published around 20 scientific articles in international journals. 

This chapter attempts to provide a critical review of the work carried out on alkaline fuel cell, which directly uses hydrogen rich liquid fuel and oxygen or air as an oxidant. The subjects covered are electrode materials, electrolyte, half-cell analysis and single cell performance in alkaline medium. Koscher et al. (2003) brought out elaborate review work on direct methanol alkaline fuel cell. Earlier Parsons et al. (1988) reviewed literature on anode electrode where, the oxidation of small organic molecules in acid as well as in alkaline conditions was considered. A review work on electro-oxidation of boron compounds was done by Morris et al. (1985). However, in this chapter use of three specific fuels, e.g., methanol, ethanol and sodium borohydride in alkaline fuel cell is discussed. 

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... 

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