Electrooxidation mechanism

The observation of an emission of light is unambiguous proof of the existence of the unstable radical intermediate C in the electrooxidation mechanism. In this way, various radical intermediates were proved and mechanisms estimated (e.g., anodic oxidation of NADH [i]). Ref. [i] Ludvik J, Volke J (1988) Anal Chim Acta 209 69 [ii] Lai RY, Bard AJ (2003) J Phys Chem A 107 3335... 

Another carbon xerogel was nsed as snpport for Pt and Pt-Ni catalysts used in methanol electrooxidation in an alkaline medinm [87], The performance of Pt-Ni was shown to be snperior to that of Pt-snpported catalysts by electrocatalytic tests. Different shapes in the cyclic voltammograms of these catalysts indicated different electrooxidation mechanisms. 

A high surface structure sensitivity in the oxidation of CO adsorbates was found. The electrooxidation mechanism is described in terms of three stages ... 

The first in-depth study of the electrooxidation mechanism of a biologically important catecholamine was that of Hawley and co-workers who investigated the bahavior of epinephrine (3). This compound, often called adrenaline. 

A mathematical model for DEFC was proposed by Pramanik and Basu describing different overpotentials [191]. The assumptions of their model are (i) the anode compartment considered as a well-mixed reactor, (ii) 1 bar pressure maintained both at the anode and cathode compartments, (iii) the transport processes are modelled in one dimension. The model accounts for Butler-Volmer-based descriptions of the ethanol electrooxidation mechanisms, diffusive reactants transport and ohmic losses at the electrode, current collector and electrode-current collector interfaces. The experiment data on current-voltage characteristics is predicted by the model with reasonable agreement and the influence of ethanol concentration and temperature on the performance of DEFC is studied by the authors (Fig. 8.19). 

Markovic NM, Gasteiger FIA, Ross PN, Jiang XD, Villegas I, Weaver MJ (1995) Electrooxidation mechanisms of methanol and formic acid on Pt-Ru alloy surfaces. Electrochim Acta 40 91-98... 

M. Niculescu, T. Ruzgas, C. Nistor, I. Frebort, M. Sebela, P. Pec, E. Csoregi, Electrooxidation mechanism of biogenic amines at amine oxidase modified graphite electrode, Analytical Chemistry 2000, 72, 5988. 

Since around 1960, the formic acid electrooxidation mechanism has been investigated, resulting in several review articles [15-18]. Formic acid electrooxidation studies have been carried out on pure metal electrodes, such as platinum (Pt) [19], palladium (Pd) [20], gold [21-23], rhodium [24, 25], and iridium [26]. Studies have also been performed on alloys, intermetallics, and adatoms. The conversion efficiency is determined by the rate of a series of steps (a) reactant adsorption, (b) electrooxidation, and (c) product desorption. The electrooxidation... 

Fig. 3.1 Catalyst-mediated formic acid electrooxidation mechanisms (a) ensemble/ third-body effect and (b) bifunctional mechanism. The catalyst atoms (open circle) commonly Ft or Pd and (filled circle) secondary metal atom...

The ethanol electrooxidation mechanism on platinum electrodes in acidic solution has been studied by various techniques and a number of adsorbed intermediates have been identified [16-25]. Carbon dioxide (CO2), acetaldehyde (CH3CHO), and acetic acid (CH3COOH) are the main products of the reaction. The global... 

Our work on the electrooxidation of alcohols with homogeneous heterobimetallic catalysts was initially motivated by the advances in DMFC anodes 8,21-23). The strategy initially employed for this project was to utilize the bifunctional oxidation mechanism observed in DMFC anodes to design discrete bimetallic complexes as catalysts for the electrooxidation of renewable fuels. These complexes can be viewed as utilizing all of the metal as opposed to bulk metal anodes, where the reaction occurs only at active surface sites. Although bimetallic complexes are not accurate models of the proposed surface binding site on bulk metal anodes, our investigations address the question of whether it is possible to reproduce the essential functions of the proposed electrooxidation mechanism in discrete heterobinuclear complexes 24-26). 

Remarkably, the scarce pioneering studies of the ethanol electrooxidation reaction already identified acetic acid (AA) and acetaldehyde (AAL) as the major products of the electrooxidation of ethanol in acid medium with a minority production of CO2 [9,10]. In spite of the enormous body of work published during the last years, and of the availability of powerful in situ diffraction and spectroscopy methods coupled to electrochemical techniques (EC-FTIR, OEMS, Raman, X-ray) features such as the actual electrooxidation mechanism, reaction kinetics, the nature of the active site(s) and accurate identification reaction intermediates of the electrooxidation of small organic molecules remain elusive, especially when molecules containing C—C bonds such as ethanol are involved. 

A.E. Coleman, H.H. Richtol, D.A. Aikens, Electrooxidation mechanisms of hexamethylbenzene and i,5-dichlo-roanthracene, J. Electroanal. Chem. 18 (1968) 165-174. 

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