On the characterization of chemical surface groups of carbon materials.

This paper deals with the use of several methods to characterize the chemical surface groups of carbon materials. Several samples embracing a wide range of acidic and basic characteristics have been used for this purpose. The quantitative determinations have been carried out by selective titrations in aqueous solutions, thermal programmed desorption connected to mass spectrometry (TPD-MS), and ammonia adsorption-desorption, measured by thermogravimetry (TG). The results show some inconsistencies between the different experimental methods. These mainly arise because chemical transformations can be produced during the experiments. Moreover, the textural characteristics of the carbon materials and the existence of pi electrons on the graphitic planes are important factors to be considered in the discussion of the results.