Fluorine and Bromine Dual-Doped Nanoporous Carbons: Preparation and Surface Chemistry Studies
Mussabek G. Baktygerey S. Taurbayev Y. Yermukhamed D. Zhylkybayeva N. Diyuk V.E. Zaderko A. Afonin S. Mariychuk R. Kaňuchová M. Lisnyak V.V.
17 September 2024American Chemical Society
ACS Omega
2024#9Issue 3738618 - 38628 pp.
A novel method for the concurrent introduction of fluorine and bromine into the surface of nanoporous activated carbon (NAC) is evaluated. According to the method, the preheated NAC was treated with 1,2-dibromotetrafluoroethane at elevated temperatures (400-800 °C). Potentiometric and elemental analysis, nitrogen adsorption-desorption, scanning electron microscopy-energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy (XPS), and 19F solid-state NMR were used to study the NAC microstructure and changes in surface chemistry. The specific modification temperature was found to have a decisive influence on the resulting halogen content of the NAC surface. About 1.5 mmol g-1 of bromine and only 0.5 mmol g-1 of fluorine are chemisorbed on the NAC surface when dual-doped at 400 °C. The fluorination efficiency increases dramatically to 1.84-2.22 mmol g-1 when the process temperature is increased to 500-700 °C. Under the same conditions, the bromination efficiency unexpectedly decreases to 0.66-1.32 mmol g-1. Since halogen-containing groups undergo significant thermal decomposition around 800 °C, the overall halogenation efficiency decreases, accordingly. Both the volume and surface area of the micropores decrease moderately when halogen-containing groups are introduced into the carbon surface layer. Fluorine and bromine are unevenly distributed in the porous structure of the dual-doped NACs, and the outer surface is more halogen-rich than the inner surface of the micropores. XPS and 19F solid-state NMR revealed the selective formation of CF2 groups in the NAC surface layer independent of the temperature. In contrast, the percentage of semi-ionic fluorine in the form of CF groups directly bonded to the π-electron system of the carbon matrix increases significantly with temperature.
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Nanotechnological Laboratory of Open Type, Al-Farabi Kazakh National University, 71, Al-Farabi Avenue, Almaty, 050040, Kazakhstan
Institute of Information and Computational Technologies, 125, Shevchenko Street, Almaty, 050012, Kazakhstan
Faculty of Chemistry, Taras Shevchenko National University of Kyiv, 62a, Volodymyrska Street, Kyiv, 01601, Ukraine
Light Matter Institute, UMR-5306, Claude Bernard University of Lyon/CNRS, Université de Lyon, Villeurbanne, Cedex69622, France
Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, Karlsruhe, 76021, Germany
Department of Ecology, Faculty of Humanities and Natural Sciences, University of Prešov in Prešov, 17 November 11, Prešov, 08001, Slovakia
Institute of Earth Resources, Faculty of Mining, Ecology, Process Control and Geotechnology, Technical University of Košice, Letná 9, Košice, 042 00, Slovakia
Western Caspian University, 31, Istiglaliyyat Street, Baku, AZ 1001, Azerbaijan
Institute of Macromolecular Chemistry, The National Academy of Sciences of Ukraine, 48, Kharkivske Shose, Kyiv, 02160, Ukraine
Nanotechnological Laboratory of Open Type
Institute of Information and Computational Technologies
Faculty of Chemistry
Light Matter Institute
Institute of Biological Interfaces (IBG-2)
Department of Ecology
Institute of Earth Resources
Western Caspian University
Institute of Macromolecular Chemistry
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