Surface Chemistry of Carbon

Apart from manifold structures, carbons can have various shapes, forms, and textures, including powders with different particle size distributions, foams, whiskers, foils, felts, papers, fibers [76, 77], spherical particles [76] such as mesocarbon microbeads (MCMB s) [78], etc. Comprehensive overviews are given, for example in [67, 71, 72], Further information on the synthesis and structures of carbonaceous materials can be found in [67, 70, 72, 75, 79]. Details of the surface composition and surface chemistry of carbons are reviewed in Chapter II, Sec. 8, and in Chapter III, Sec. 6, of this handbook. Some aspects of surface chemistry of lithiated carbons will also be discussed in Sec. 5.2.2.3. 

The ideas developed here are largely based on the concept of the coordination at the (hydr)oxide interface the ideas apply equally well to silicates. Somewhat modified concepts for the surface chemistry of carbonate, phosphate, sulfide and disulfide minerals have to be developed. 

Laszlo K, Tombacz E, Josepovits K et al (2001) Effect of activation on the surface chemistry of carbons from polymer precursors. Carbon 39(8) 1217-1228... 

Morse J.W. (1986) The surface chemistry of carbonate minerals in natural waters An overview. Mar. Chem. 20, 91-112. 

How much Conway appears to be out of touch with carbon (electrochemistry research is confirmed by his discussion of a 1972 paper by Thrower, presumably published in J Electroanal Chem anyone familiar with Peter Thrower s expertise—and that means any serious carbon researcher—knows that such a paper cannot (and does not ) exist. Finally, in the light of recent proposals regarding the edge chemistry of carbon surfaces [6], Conway s conclusion that [m]any porous or powder[ed] carbon materials have dangling surface bonds which are associated with free-radical behavior should also be viewed with caution (see Figure 5.4). Therefore, perhaps the most (and only ) reliable take-home message from this review is that much basic research of a substantive kind is required to relate the electrochemical behavior of various preparations more quantitatively to... (5) the surface chemistry of carbon preparations and their shelf-life stability, cycle life, and self-discharge characteristics. ... 

Needless to say that a deep understanding of both the formation mechanism of the SEI layer and the underlaying question of carbon s surface chemistry in a particular electrolyte solution is of utmost importance for battery developers. Clearly, the surface chemistry of graphite electrodes plays a key role in their performance.259 312 325 343-352 A lot of work was devoted to decipher this very complicated surface chemistry. It is therefore not surprising that the advancement in the understanding of surface chemistry of carbon electrodes in nonaqueous electrolytes correlates well with the worldwide production rate of lithium-ion batteries. 

B. Surface Chemistry of Carbon Electrodes Polarized to Low Potential in Polar Aprotic Systems and Related Potentiodynamic Behavior... 

The surface chemistry of carbon is of relevance to all aspects of catalytic carbon chemistry. The two most important heteroelements are hydrogen and oxygen. Each element can undergo a variety of chemically different coordinations which need to be discriminated in analyses of the chemical function of the carbon-heteroatom bond. In the literature the term surface complex is often used to described a group of chemically different bonds which could not be specified in detail. 

The surface chemistry of carbon is rather complex. At a single adsorption site several chemically inequivalent types of heteroatom bonds may form. Strong interactions between surface functional groups further complicate the list of surface chemical structures as derived for the most relevant carbon-oxygen system An additional dimension of complexity is presented by the large variety of substrate structures of carbon which arise from anisotropic covalent bonding rather than by a isotropic metallic interaction. 

J. Kiippers The hydrogen surface chemistry of carbon as a plasma facing material. Surf. Sci. Rep. 22, 249 (1995)... 

Extensive efforts have been made to characterize the surface chemistry of carbon blacks. Although carbon blacks are nearly all carbon, impurities of oxygen, sulfur, nitrogen and small amounts of other elements are present. Most of the work has centered around the identification and quantification of oxygen containing... 

The surface chemistry of carbon has been extensively studied and reviewed (14-18). It is generally believed that a variety of carbon-oxygen functional groups are present on carbon surfaces. Their nature and concentration are dependent on the sample history and depend, for example, on processing variables. 

Oxidation and incorporation of nitrogen usually affect the surface chemistry of carbons [12, 20, 24]. The types and numbers of basic and acidic groups evaluated using Boehm titration [3, 4]. are collected in Table 2. The data reported indicate that the initial carbons differ in their acidity as a result of the activation method and the type of an organic precursor [1]. BAX is more acidic than BPL. This is expected for a phosphoric acid activated carbon [25]. After modification with urea and heat treatment at 723 and 1223 K, the overall surface chemistry... 

Zawadzki J (1989) Infrared-spectroscopy in surface-chemistry of carbons. Chem Phys Carbon 21 147-380... 

The essential features of the surface chemistry of carbons, relevant to their behavior in aqueous solution, are summarized in Figs. 2 and 3. These are discussed in more detail elsewhere [37[, and the reader will appreciate from such discussions that the features presented here are perhaps gross (over)simplifica-tions we shall argue here that they are also very convenient and useful simplifi-... 

FIG. 19 Relationship between adsorption capacities of dyes and the surface chemistry of carbon. (Adapted from Ref. 451.)... 

Microporous Structure of Activated Carbons as Revealed by Adsorption Methods, Francisco Rodn guez-Reinoso and Angel Linares-Solano Infrared Spectroscopy in Surface Chemistry of Carbons, Jerzy Zawadzki... 

Boehm, H.-P. (1994). Some aspects of the surface chemistry of carbon blacks and other carbons. Carbon, 32, 759-69. 

Puri, B.R. and Bansal, R.C. (1964). Studies in surface chemistry of carbon blacks. Part II. Surface acidity in relation to chemisorbed oxygen. Carbon, 1, 457—64. 

Zawadski, J. (1989). Infrared spectroscopy in surface chemistry of carbons. In Chemistry and Physics of Carbon, Vol. 21 (P.A. Thrower, ed.). Marcel Dekker, pp. 147-380. 

Free radical states have an important role in the surface chemistry of carbons. They are formed as a result of thermal splitting of the C—H bonds to produce carbon rings. Unpaired electrons stabilize by occupying a molecular orbital in the TT-bond system. The ratio between the electron density in the TT-bond system and conduction electrons depends on temperature and on the treatment of the material. 

The adsorption of organic electrolytes is a more complicated process than that of nonelectrolytes because it is a complex interplay between electrostatic and nonelectrostatic interactions. In this section, I present results obtained with three representative types of organic electrolytes phenol and its derivatives, dyes, and surfactants. These observations demonstrate the importance of the surface chemistry of carbons on the adsorption processes. 

The series of 10 chapters that constitute Part 3 of the book deals mainly with the use of adsorption as a means of characterizing carbons. Thus, the first three chapters in this section complement each other in the use of gas-solid or liquid-solid adsorption to characterize the porous texture and/or the surface chemistry of carbons. Porous texture characterization based on gas adsorption is addressed in Chapter 11 in a very comprehensive manner and includes a description of a number of classical and advanced tools (e.g., density functional theory and Monte Carlo simulations) for the characterization of porosity in carbons. Chapter 12 illustrates the use of adsorption at the liquid-solid interface as a means to characterize both pore texture and surface chemistry. The authon propose these methods (calorimetry, adsorption from solution) to characterize carbons for use in such processes as liquid purification or liquid-solid heterogeneous catalysis, for example. Next, the surface chemical characterization of carbons is comprehensively treated in Chapter 13, which discusses topics such as hydrophilicity and functional groups in carbon as well as the amphoteric characteristics and electrokinetic phenomena on carbon surfaces. 

---