Carbon Nano-onions: Potassium Intercalation and Reductive Covalent Functionalization


Herein we report the synthesis of covalently functionalized carbon nano-onions (CNOs) via a reductive approach using unprecedented alkali-metal CNO intercalation compounds. For the first time, an in situ Raman study of the controlled intercalation process with potassium has been carried out revealing a Fano resonance in highly doped CNOs. The intercalation was further confirmed by electron energy loss spectroscopy and X-ray diffraction. Moreover, the experimental results have been rationalized with DFT calculations. Covalently functionalized CNO derivatives were synthesized by using phenyl iodide and n-hexyl iodide as electrophiles in model nucleophilic substitution reactions. The functionalized CNOs were exhaustively characterized by statistical Raman spectroscopy, thermogravimetric analysis coupled with gas chromatography and mass spectrometry, dynamic light scattering, UV-vis, and ATR-FTIR spectroscopies. This work provides important insights into the understanding of the basic principles of reductive CNOs functionalization and will pave the way for the use of CNOs in a wide range of potential applications, such as energy storage, photovoltaics, or molecular electronics.



subject category

Chemistry, Multidisciplinary


Perez-Ojeda, ME; Castro, E; Krockel, C; Lucherelli, MA; Ludacka, U; Kotakoski, J; Werbach, K; Peterlik, H; Melle-Franco, M; Chacon-Torres, JC; Hauke, F; Echegoyen, L; Hirsch, A; Abellan, G

our authors


The work was supported by the European Union (ERC Advanced Grant 742145 B-PhosphoChem to A.H., ERC-2018-StG 804110-2D-PnictoChem to G.A.), the German Research Foundation (DFG) (Project-ID 182849149 SFB 953 Synthetic Carbon Allotropes project A1 (A.H.), project A9 (M.E.P.-O.), as well as FLAG-ERA AB694/2-1 (G.A.)), and the Spanish MICINN (PID2019-111742GA-I00, Maria de Maeztu Program for Units of Excellence in R&D CEX2019-000919-M). G.A. acknowledges support by the Generalitat Valenciana (CIDEGENT/2018/001 and iDiFEDER/2018/061 cofinanced by FEDER). M.E.P.-O. acknowledges support by Emerging Talents Initiative (ETI) from FriedrichAlexander Universitat Erlangen-Nurnberg. M.M.-F. acknowledges support through the project IF/00894/2015 and within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020 funded by national funds through the Portuguese Foundation for Science and Technology I.P./MCTES. In addition, the research leading to these results has received partial funding from the European Union Seventh Framework Program under Grant Agreement No. 604391 Graphene Flagship. L.E. and E.C. would like to thank the US NSF for the generous support of this work under CHE-1801317 and to the Robert A. Welch Foundation for an endowed chair to L.E. (Grant AH-0033).

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