Surface Groups on Carbon

Microcrystalline carbon was formerly called amorphous carbon. It is known in many varieties active carbons, carbon blacks, carbon 

Most important and best known among the surface compounds of carbon are those with oxygen and with sulfur. Other elements, e.g., chlorine and hydrogen, can also serve as end groups.  

The oxygen was adsorbed irreversibly it was not liberated in molecular form on addition of alkali 17). 

An electrochemical explanation of the basic reaction was suggested by P rumkin 17), while Shilov et al. 22, 23) claimed surface oxides of definite structure to be the only cause of either acidic or basic reaction. Shilov formulated the acidic surface oxides as carboxylic acid anhydrides bound to the edges of the carbon layers. 

two kinds of surface oxides became known. Basic surface oxides are formed always when a carbon surface is freed from all surface compounds by heating in a vacuum or in an inert atmosphere and comes into contact with oxygen only after cooling to low temperatures. As is now known 24), the irreversible uptake of oxygen starts at ca. —40° there is only reversible, physical adsorption at lower temperatures. Acidic surface oxides are formed when carbon is treated with oxygen at temperatures near its ignition point. King 21) found the maximum 

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Fig. 15.5 Oxygen and nitrogen surface groups on carbon, (a) lactone, (b) carboxylic anhydride,...

Consumptive Absorption. There remain differences of consumptive absorption by the carbon, and it is reasonable that they should vary with the method of preparation. For example, carbons generally contain unpaired electrons (34), and this free radical character, at least during formation, is a function of position in the flame (27). That the free radical character should differ for soot and lampblack is therefore at least plausible, as is the dependence of light absorption on this character. Surface groupings on carbons can also differ (35), and this could affect light absorption. Thus, the various tints seen in thin washes of Chinese ink can be considered a result of differences in the consumptive light absorption by the carbon, and they may well reflect different methods of preparation. 

Behler K, Osswald S, Ye H, Dimovski S et al (2006) Effect of thermal treatment on the structure of multi-walled carbon nanotubes. J Nanopart Res 8 615-625 Fanning PE, Vannice MA (1993) A drifts study of the formation of surface groups on carbon by oxidation. Carbon 31(5) 721-730... 

Fourier transform infrared (FTIR) and in-situ FTIR spectroscopy are among many modern instrumental tools of analytical chemistry well established in fuel-cell-related electrochemistry [1]. In general, FTIR spectroscopy is a valuable tool in the characterization of fuel cell technical electrodes, where the nature of surface groups can be identified, since such electrodes are rather difficult solid surfaces on which to work. FTIR is among the methods less commonly used for the characterization of dispersed catalysts and supports, but as a technique is able to give an idea about the nature of the surface groups on carbon supports and on the structure of adsorbed species on noble metal clusters. 

Surface Groups on Carbons and Catalyst Preparation Procedures... 

SURFACE GROUPS ON CARBONS AND CATALYST PREPARATION PROCEDURES... 

The relation between electronic conductivity and chemical reactivity is well established, particularly for graphites.However the suggestion that the detailed chemistry of surface complexes depends on the immediate pretreatment of the surface, makes consideration of surface complexes of carbons very difficult. To quote Papirer et al Major progress in the knowledge of the surface groups on carbons must be expected only if entirely new analytical tools become available. Although this statement seems too... 

The characterization of carbon surfaces is commonly carried out by numerous techniques. An up-to date review of this subject will be later presented in Section 4. The investigation of surface groups on carbon materials by electrochemical techniques is discussed in this section. 

Fanning, RE. and Vannice, M.A. 1993. A DRIFTS study of the formation of surface groups on carbon by oxidation. Carbon 31 121-730. 

Short chain branching in polyethylene decreases adsorbed polymer chain on the sur-faee of carbon nanotubes. Simulation study shows that the carbon nanotube seems to inerease more effieiently the polyethylene crystalhnity in the case of the branched chains than in the hnear ones. The presenee of surface groups on carbon nanotubes reduced their ability to nueleate poly(L-laetie aeid). At high supercooling, where homogeneons nucle-ation is prevalent, the addition of earbon nanotubes does not affect the crystallization rate ofPCL. 

Several spectroscopic techniques have been used to investigate the presence of carbon-oxygen surface groups on carbons. Infrared (IR) and electron spin resonance (ESR) are the two most commonly used spectroscopic techniques, although in more recent years, x-ray photoelectron spectroscopy (XPS) has been increasingly applied for the... 

Infrared Adsorption Peaks and Signals for Different Surface Groups on Carbons... 

Influence of chemisorbed hydrogen on carbon surfaces. A review of standard methods of formation of surface groups on carbon surfaces is published by Fanning and Vannice... 

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