Carbon monoxide electrochemistry

Here iii " and mout denote the mass flow rate of the mixture entering from the inlet and leaving from the outlet respectively. Rate of consumption and rate of production of each species A is denoted by m sed and mv d. These rates include the flux of reactants, which take part in electrochemical reactions, across the chan-nel/electrode interfaces and also the consumption and production of species due to methane reforming reaction on the anode side. Both hydrogen and carbon monoxide electrochemistry was considered and it was assumed that n2, the fraction of the current that is produced from H2 oxidation, is known. Thus the specie consump-... 

Palaikis L, Zurawski D, Hourani M, Wieckowski A. 1988. Surface electrochemistry of carbon monoxide adsorbed from electrolytic solutions at single crystal surfaces of Pt(lll) and Pt(lOO). Surf Sci 199 183-198. 

Although the electrochemistry of organic compounds is the focus of the next chapter, several carbon molecules are more appropriate to the present discussion of nonmetals. Carbon dioxide (C02, 0=C=0) and carbon monoxide (CO, C = 0 ) are the products of hydrocarbon combustion, and cynanide ion (CN NC", N = C ) is unique with respect to a stable carbon-centered anion. 

As discussed above, reduction of metal-metal bonded complexes is common, particularly for carbon monoxide-substituted complexes. The electrochemical potential of these reactions has been widely studied (see Electrochemistry Applications in Inorganic Chemistry). In addition, Meyer has shown that the metal-metal bond strength can be estimated via electrochemical techniques. The results applied to Mn2(CO)io are in agreement with values obtained by other methods and could provide a means of generating a wide range of metal-metal bond strengths. The legs of the electrochemical cycle are shown in equation (99). 

After the brief introduction to the modem methods of ab initio quantum chemistry, we will discuss specific applications. First of all, we will discuss some general aspects of the adsorption of atoms and molecules on electrochemical surfaces, including a discussion of the two different types of geometrical models that may be used to study surfaces, i. e. clusters and slabs, and how to model the effect of the electrode potential in an ab initio calculation. As a first application, the adsorption of halogens and halides on metal surfaces, a problem very central to interfacial electrochemistry, will be dealt with, followed by a section on the ab initio quantum chemical description of the adsorption of a paradigmatic probe molecule in both interfacial electrochemistry and surface science, namely carbon monoxide. Next we will discuss in detail an issue uniquely specific to electrochemistry, namely the effect of the electric field, i. e. the variable electrode potential, on the adsorption energy and vibrational properties of chemisorbed atoms and molecules. The potential-dependent adsorption of carbon monoxide will be discussed in a separate section, as this is a much studied system both in experimental electrochemistry and ab initio quantum electrochemistry. The interaction of water and water dissociation products with metal surfaces will be the next topic of interest. Finally, as a last... 

Park, S., Y.T. Tong, A. Wieckowski, and M.J. Weaver, Infrared spectral comparison of electrochemical carbon monoxide adlayers formed by direct chemisorption and methanol dissociation on carbon-supported platinum nanoparticles. Langmuir, 2002.18(8) pp. 3233-3240 Park, S., Y. Tong, A. Wieckowski, and M.J. Weaver, Infrared reflection-absorption properties of platinum nanoparticle films on metal electrode substrates control of anomalous opticalejfects. Electrochemistry Communications, 2001. 3(9) pp. 509-513 Park, S., P.K. Babu, A. Wieckowski, and M.J. Weaver, Electrochemical infrared characterization of CO domains on ruthenium decorated platinum nanoparticles. Abstracts of Papers of the American Chemical Society, 2003. 225 pp. U619-U619... 

Mu, X.H. and K.M. Kadish (1989). Oxidative electrochemistry of cobalt tetraphenylporphyrin under a CO atmosphere. Interaction between carbon monoxide and electrogenerated [(TPP)Co]+ in nonbonding media. Inorg. Chem. 28, 3743-3747. 

In comparison with the PEFC, the HT-PEFC requires a description of the electrochemistry with modification to higher tolerance against carbon monoxide (CO) and a simpler approach to fluid flow because of the absence of liquid water. The CO tolerance requires special submodels that account for the reversible decrease in catalyst activity if the fuel is reformate gas. Compared with the SOFC, the HT-PEFC requires different electrochemical parameters because of the very different catalysts and operating temperatures and the use of H+ instead of 0 as charge carrier. Thermomechanical stress is less important because of the much more moderate operating temperature. 

CO adsorption and oxidation have been studied for many years, but a greater understanding was achieved by the development of ex situ and in situ spectroscopic and microscopic methods for application in electrochemistry [9, 143-146], together with the use of well-defined nanocrystalline electrode surfaces [147]. The opportunity to study in situ electrooxidation of carbon monoxide [148-157] under fuel cell reaction conditions has brought significant progress in understanding interfacial electrochemistry on metallic surfaces, hi combination with conventional electrochemical methods these techniques have been used to find connections between the microscopic surface structures and the macroscopic kinetic rates of the reactions. 

Kawaguchi, T., Sugimoto, W., Muratami, Y., and Takasu, Y. (2004) Temperature dependence of the oxidation of carbon monoxide on carbon supported Pt, Ru, and PtRu. Electrochemistry Communications, 6 (5), 480-483. 

---