Graphitic and Nongraphitic Carbons

Because of the variety of available carbons, classification is inevitable. Most carbonaceous materials which are capable of reversible hthium intercalation can be classified roughly as graphitic and nongraphitic (disordered). 

The surface structure has a strong influence on the corrosion rate of carbon in both acid and alkaline electrolytes. Studies by Kinoshita [33] clearly showed that the specific corrosion rate mAcm"2 of carbon black in 96 wt% H3P04 at 160 °C was affected by heat treatment. A similar trend in the corrosion rate in alkaline electrolyte was observed by Ross [30c], as shown in Fig. 4. It is evident that the corrosion rates of the nongraphitized carbons are higher than those of the corresponding graphitized carbons. Their study further indicated that some types of carbon blacks (e.g., semi... 

Figure 32. Schematic representation of the modes of fixation of metal particles on graphitic surfaces. A stack of graphene layers with a step edge is shown with a metal particle (granite pattern) and surface anchoring groups (black). Nongraphitic carbon deposits are shown in dark grey with fading contrast (bottom sketch).

As mentioned earher, the nongraphitic carbons can be classified into two categories, soft and hard carbons. Different levels of graphitization can be obtained from the nongraphitic carbon materials, depending essentially on the heat treatment... 

Thus, the surface of this amorphous carbon (which is a model of the surfaces of non-graphitized carbon blacks [23]) differs considerably from the surface of amorphous oxide and the main structural characteristics such as the C-C and 0-0 coordination numbers are also drastically different. Nevertheless, the adsorption properties of heterogeneous surfaces of various nongraphitized carbon blacks with respect to an inert adsorbate such as argon are not that drastically different and actually have many common features. We discuss these properties in the next section. Here we only use this fact to show that subtle structural differences of various models of amorphous oxide surfaces discussed above may be not that important for their adsorption properties in comparison to other factors such as indefiniteness of adsorption potential on oxide surfaces (see below). Because of its generality and in spite of its approximate character, the BS appears to be a convenient model for the computer simulation of adsorption on amorphous, and even more general (see Introduction) heterogeneous oxide surfaces. 

---