ABSTRACT
I. Introduction: Carbonaceous Materials................................................... 130 A. Carbon Materials Used in Heterogeneous Catalysis .........................131 B. Carbon Materials Used as Adsorbents ............................................. 134 II. Characterization of Surface Chemistry in Terms of Functional
Groups .................................................................................................... 137 A. Carbon Acidity ................................................................................. 137 B. Carbon Basicity ................................................................................ 138 C. Point of Zero Charge (PZC), Isoelectric Point (IEP), and
Electrochemical Methods ................................................................ 140 D. Temperature-Programmed Desorption (TPD) ..................................141 E. Immersion Calorimetry .................................................................... 142 III. Surface Characterization in Terms of Active, Polar, and
Nonpolar Sites .........................................................................................143 IV. Application of Calorimetric Methods to Characterization
of Surface Chemistry ............................................................................. 145 A. Immersion and Flow Adsorption Calorimetry ................................ 145 B. Immersion Calorimetry in Water ......................................................147 C. Gas Adsorption Calorimetry ............................................................ 148 V. Spectroscopic Characterization of Carbon Surface Chemistry ............. 150 A. Infrared Spectroscopy ...................................................................... 150 B. X-Ray Photoelectron Spectroscopy (XPS) ...................................... 153 C. XPS Combined with Solid-State NMR Spectroscopy ..................... 156 VI. Characterization of Surface Chemistry in Terms of Molecular
Interactions ............................................................................................. 159 A. Work of Adhesion ............................................................................ 159 B. Inverse Gas Chromatography (IGC) .................................................161 VII. Conclusions ............................................................................................. 166 Acknowledgments ............................................................................................. 168 References ......................................................................................................... 169
The term carbonaceous materials covers a large set of products with different degrees of functionalization. Their applications are diverse and, for many of them, are based on a good knowledge of their surface properties. These can be described in different ways, according to miscellaneous concepts that will be detailed in this chapter. Investigations of the surface of such materials require physicochemical, thermodynamic, and spectroscopic approaches with the aim of improving understanding of their behavior. The importance of the surface chemistry of carbonaceous materials, besides their surface area and porosity, to explain many of their properties in numerous applications began to be widely recognized only in the 1980s [1]. In particular, the amphoteric character of carbons, with both acidic and basic centers coexisting on their surface, was pointed out [1,2]. The presence of various functional groups on the carbon surface depends on the nature of the base material and on the activation technique employed in the manufacturing process. Furthermore, special posttreatments can modify the surface chemistry, resulting in new useful properties.
