SKM 2023 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 27: Overview Talk Michael Gottfried

O 27.1: Hauptvortrag

Dienstag, 28. März 2023, 09:30–10:15, TRE Phy

Beyond Graphene: On-Surface Synthesis Unlocks New Carbon Allotropes — •J. Michael Gottfried — Department of Chemistry, Philipps-Universität Marburg, 35032 Marburg, Germany

The quest for planar sp²-hybridized carbon allotropes other than graphene, such as phagraphene and biphenylene network, has stimulated substantial research efforts because of the materials’ predicted unique mechanical, electronic, and transport properties. However, their syntheses remain challenging due to the lack of reliable protocols for generating non-hexagonal rings during the in-plane tiling of carbon atoms. We have developed an on-surface synthesis strategy by which we first make straight polymer chains, which then link to form the nonbenzenoid graphene isomers. In this way, we synthesized biphenylene network with periodically arranged four-, six-, and eight-membered rings, through an on-surface inter-polymer dehydrofluorination reaction. Biphenylene network is the only experimentally known planar sp² carbon so far, besides graphene. Its characterization by scanning probe methods reveals that it is metallic rather than a dielectric already at very small dimensions [1]. A complementary approach was used to generate phagraphene nanoribbons based on five-, six- and seven-membered rings. Here, we polymerized an azulene-based precursor containing the odd-numbered rings. Additional four- and seven-membered rings can be formed during dehydrogenative C-C coupling of the intermediate 2,6-polyazulene chains, resulting in tetra-penta-hepta(TPH)-graphene with metallic properties [2].

[1] Q.T. Fan, L.H. Yan, M.W. Tripp, O. Krejči, S. Dimosthenous, S.R. Kachel, M.Y. Chen, A.S. Foster, U. Koert, P. Liljeroth, J.M. Gottfried, Science 372, 852-856 (2021).

[2] Q.T. Fan, D. Martin-Jimenez, D. Ebeling, C.K. Krug, L. Brechmann, C. Kohlmeyer, G. Hilt, W. Hieringer, A. Schirmeisen, J.M. Gottfried, J. Am. Chem. Soc. 141, 17713-17720 (2019).