Insights on the reactivity of ordered porous carbons exposed to different fluorinating agents and conditions

Abstract

The fluorination of porous carbonaceous materials was systematically investigated employing different fluorinating agents (molecular F2 and atomic F released by XeF2 decomposition) and conditions (static and dynamic). Two ordered porous carbonaceous materials, that is, mesoporous silica-templated carbon (STC) and microporous zeolite-templated carbon (ZTC), were synthesized along with a microporous commercial carbonaceous material (CPC) for comparison purposes. Besides the different textural features (specific surface area and pore size), the materials present distinct surface chemistries in terms of functional group types and quantity. The influence of material characteristics on the formed fluorinated carbonaceous materials was investigated by several analysis techniques. Thus, the nature, strength, and thermal stability of the C–F bonds was assessed by 13C and 19F nuclear magnetic resonance, Fourier transform infrared spectroscopy, and temperature-programmed desorption coupled with mass spectrometry. The modification of porous texture and organization was carried out by nitrogen adsorption, small-angle X-ray scattering, and transmission electron microscopy. Based on these techniques, the following classifications could be established according to the carbon reactivity under a fluorine atmosphere and employing the fluorination method: STC>ZTC≫CPC and F2 static>F2 dynamic>XeF2. The reactivity of the materials is driven by their rich surface chemistry (STC) and high surface area (ZTC).