Tuning the Acid/Base Properties of Nanocarbons by Functionalization via Amination

作者：Rosa Arrigo, Michael Hävecker, Sabine Wrabetz, Raoul Blume, Martin Lerch, James McGregor, Edward P. J. Parrott, J. Axel Zeitler, Lynn F. Gladden, Axel Knop‐Gericke, Robert Schlögl, Dang Sheng Su · 发表于：Journal of the American Chemical Society · 年份：2010 · DOI：10.1021/ja910169v · 被引用次数：717 · 研究领域：Graphene research and applications、Carbon Nanotubes in Composites、Molecular Junctions and Nanostructures

The surface chemical properties and the electronic properties of vapor grown carbon nanofibers (VGCNFs) have been modified by treatment of the oxidized CNFs with NH(3). The effect of treatment temperature on the types of nitrogen functionalities introduced was evaluated by synchrotron based X-ray photoelectron spectroscopy (XPS), while the impact of the preparation methods on the surface acid-base properties was investigated by potentiometric titration, microcalorimetry, and zeta potential measurements. The impact of the N-functionalization on the electronic properties was measured by THz-Time Domain spectroscopy. The samples functionalized via amination are characterized by the coexistence of acidic and basic O and N sites. The population of O and N species is temperature dependent. In particular, at 873 K nitrogen is stabilized in substitutional positions within the graphitic structure, as heterocyclic-like moieties. The surface presents heterogeneously distributed and energetically different basic sites. A small amount of strong basic sites gives rise to a differential heat of CO(2) adsorption of 150 kJ mol(-1). However, when functionalization is carried out at 473 K, nitrogen moieties with basic character are introduced and the maximum heat of adsorption is significantly lower, at approximately 90 kJ mol(-1). In the latter sample, energetically different basic sites coexist with acidic oxygen groups introduced during the oxidative step. Under these conditions, a bifunctio...