Edge carbon atoms

Figure 6 Polyhedral view (to scale) of structure types ai(a), a2(b) and two orientations of 03(0 and d) for CtqMu. The muon is at the end of the dangling bond and in views (a) and (b) lies in the plane of the paper. For views (a), (b) and (c) four edge carbon atoms are also in the plane of the paper. The other visible atoms are above the paper. Each atom above the paper hides a corresponding atom below the paper except for type 03 where in the region of the muon the undistorted structure below the plane is shown with dashed lines. This is useful since it clearly shows the nature of the distortion. View (d) is an orientation of type 03 to illustrate that the distortion is similar to the other type a structures...

Quantum Mechanical Treatment of Graphite. Various quantum mechanical models have been proposed to account for difference in reactivity for different carbon atoms in graphite. Busso, Daudel, and coworkers (12) calculate free valence for various types of edge carbon atoms. Busso (9) summarized these as shown below. 

FIGURE 5.11 Proposed mechanisms of participation of N heteroatoms in electrochemical processes on carbon surfaces (a) possible pseudo-Faradaic reaction of the pyridinic group in aqueous medium [95] (b) N-induced stabilization of carbene-like edge carbon atoms, sites responsible for the development of positive charge in acidic solution. 

Figure 16.4 Upper panel shows a benzenoid cluster model (C96H24) and nonbenzenoid models (C80H2o, C112H2a). Lower panel shows the unoccupied C 2p-DOS and C 2s-DOS of carbon atoms in the cluster models. Carbon atoms from the centered atoms to the edged atoms are numbered as 1C-7C, respectively. Hydrogen atoms terminating the edged-carbon atoms are numbered as 8H. The lower-energy DOS portions at the n peak positions of 1C and 7C are denoted by arrows. For a colour version of this figure please see the colour plate section near the end of the book.

Consequently, it has been confirmed that the broad n peak features in the XAS of CB can provide local structure information, especially on the nonbenzenoid structure and/or hydrogenated cluster-edged carbon atoms. 

The dispersion of metallic derivates on a carbon surface is dependent upon the surface properties of the carbon support. Edge carbon atoms which constitute the majority of the active surface area of graphitized carbon blacks may interact with the catalyst precursor or the catalyst itself thus providing a higher state of dispersion. 

Moreover specific interactions of the metallic derivates with the edge carbon atoms tend to decrease the sintering rate of the supported solid. 

The activation procedure has been described elsewhere (16), During the gasification, the total surface area (S et) as well as the active surface area (Sa), i.e, the area of the edge carbon atoms planes increase. The surface area data of both samples are shown in Table II. 

It is seen that the surface of V3G consists mainly of basal planes whereas about 4 % of the area of the activated V3G sample is buildup with edge carbon atoms. 

The term surface compound of carbon is restricted to chemisorption, i.e., linkage of the adsorbate to the surface by covalent bonds. Surface groups on graphite are situated on edge carbon atoms or on defect sites there is no attack of basal planes . Carbon-oxygen surface compounds are present on any black carbon in contact with air there are also surface compounds with S, H, N or halogens bonded to carbon... 

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