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This study aims to elucidate the role of hydrogen desorption profiles obtained through temperature programmed desorption (TPD) analysis of carbon materials for revealing their carbon edge sites. Accordingly, the H 2 desorption profiles of several carbon materials, such as activated carbon, carbon black, reduced graphene oxide (rGO), phenol resin carbon, graphite, high-temperature treated carbon, and carbon nanotubes (CNTs), were investigated. The kinetic analysis of the profiles revealed that H 2 desorption is a second-order reaction initiated by the association of edge hydrogen. Furthermore, the relationship between the total number of edge hydrogens in a sample and the peak temperature of H 2 desorption represents the spatial distribution of edge hydrogens in the carbon structure. Additionally, most of the activated carbons, carbon blacks, and rGOs exhibited a uniform distribution of edge hydrogen throughout their carbon structures. In contrast, the edge hydrogen in graphite, high-temperature treated carbon, and CNTs were heterogeneously distributed throughout their structures. [Display omitted] [ABSTRACT FROM AUTHOR]

A deuterium-labeled temperature-programmed desorption (TPD) technique was developed to accurately characterize functional groups on the surface of carbon-based materials. After the protic hydrogen of the functional groups on activated carbons was substituted by deuterium, TPD analysis revealed the desorption of deuterium compounds (D 2 O, DHO, D 2 , DH). The functional groups were estimated from the predicted desorption mechanisms of these deuterium compounds, which can be distinguished according to the functional groups and their surrounding chemical structures. Thus, this technique provides information on not only the type of functional groups but also the extensive chemical structure around them. The phenolic group, ether, and edge hydrogen formed on the activated carbons were separately quantified, and the functional groups were further classified into 12 types by the nearby chemical structures. Comparison with IR spectra indicated that the deuterium-labeled TPD gave qualitatively reasonable results. This technique is useful for obtaining a deeper understanding of the surface chemical structure of carbon-based materials. Image 1 [ABSTRACT FROM AUTHOR]