Carbon surface oxides

Binder el al.51 had observed that the reaction products were carbon dioxide and carbon surface oxides and that the reaction rate was proportional to the BET surface area. These early results however, were not substantiated by Kinoshita and Bett. 

Rychlicki, G., Terzyk, A.P., and Zawadzki, J. (1994). The influence of carbon surface oxidation on thermodynamic properties of carbon-tetrachloride adsorbed at different temperatures. Polish J. Chem., 68, 557-63. 

Active carbon surface oxidation to optimize the support functionality and metallic dispersion of a Pd/C catalyst. 

Anodic oxidation of graphite 16.4.2.8.3 Carbon surface oxidation 16.4.2.7.3 Graphite residue compound 16.4.2.7.2 Intercalation into graphite oxide ... 

The most important and at the same time the most abundant heteroatom that affects the use of carbon is oxygen. It is usually either chemisorbed on the surface or arranged in the form of functional groups analogous to those existing in organic chemistry [51-54]. Since those groups increase the reactivity of the otherwise hydrophobic carbon surface, oxidation often opens the door to further... 

The formation of carbon surface oxides, phenols, quinones, lactones, and car-boxyhc acids upon the electrooxidation of carbon has been detected by physical methods such as infrared spectroscopy [262], ellipsometry [263], x-ray photoelectron spectroscopy [262,264,265], thermal desorption, and electrochemistry (see refs. [8, 96, 248, and 261] and references therein). Cyclic voltammograms of oxidized carbons exhibit increased charge in the potential interval from 0.4 to... 

Dalai and coworkers studied the adsoiption/oxidation of MM on Hydrodacro activated carbon. The experiments were carried out at elevated temperatures (323 48 K) at the pressure range between 122 and 364 kPa with the various contents of oxygen (O2/CH3SH ifom 1.1 to 1.33 times the stoichiometry ratio) [132]. At these conditions DMDS and small amounts of CO2 were formed. While the latter is likely the product of carbon surface oxidation, the conversion rate of MM increased with an increasing temperature and 99% was achieved at 373 K. It was found that... 

The positive potential limit may depend on several factors, all generally related to the mobile phase or electrc e composition. For carbon surfaces, oxidation of the mobUe phase is usually determining ... 

The ratios obtained by the two methods [S] allow elucidating the role of the carbon surface oxidation and the kind of the media (aqueous or m hanol) with req)ect to the impregnation process, i.e. to the incorporation of Cu into the intonal pore network or onto the external support surface. In our case (Table 5) there is a continuous increase of the concentration of Cu in the internal surface, which for the different samples varies between 3.1 and 9.4. The ACM... 

Figure 2.12. Hydrodynamic voltammograms for O2 reduction at a bare glassy carbon RDE in 02-saturated 0.5 M H2SO4. Glassy carbon surface oxidation time 0 min (dashed line) 1 min (thin line) 5 min (thick hne) 20 min (very thick bne). Scan rate 10 mV/s rotation speed 2000 rpm [27]. (Reprinted from Journal of Electroanalytical Chemistry, 527(1-2), Maruyama J, Abe I, Cathodic oxygen reduction at the interface between Nafion and electrochemically oxidized glassy carbon surfaces, 65-70, 2002, with permission from Elsevier.)...

Kinoshita K, Bett J. Determination of carbon surface oxides on platinum-catalyzed carbon. Carbon 1974 12 525-33. 

The corrosion rate of carbon can be accelerated in flie presence of Pt on the carbon surface. Oxidation of carbon in the presence of Pt could be accelerated by the following radical reactions [96] ... 

The generation of CO is beheved to proceed through the intermediate formation of carbon surface oxides, as suggested in earlier studies in phosphoric acid fuel cells (Kinoshita and Bett 1973). It was reported that formation of surface oxides and evolution of CO occur simultaneously during the initial corrosion of high surface area carbon blacks. Similar conclusions are also reported by recent studies of PEMFCs (Kangasniemi et al. 2004). These studies showed that the surface oxides... 

MPL is more vulnerable to carbon-surface oxidation by liquid water and dissolved Oj than the graphitized substrate-fiber surfaces (at least for the SIGRACET GDL 24 substrate type), since the contact-angle reduction of the non-MPL sides was statistically insignificant. However, this might not have been the case for a substrate material that was graphitized to a higher temperature, such as Toray TGP-H. 

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