Graphenization of graphene oxide films for strongly anisotropic thermal conduction and high electromagnetic interference shielding

Tian Xia, Jianyun Cao, Mark A. Bissett, Harry Waring, Ying Xiang, Gergo Pinter, Andrey V. Kretinin, Pei Yang, Yanlei Zhu, Xin Zhao, Stephen A. Hodge, Thomas Thomson, Ian A. Kinloch

Research output: Contribution to journalArticlepeer-review

Abstract

A macroscopic carbon film that has a “graphenic” structure (defect-free in-plane graphene lattice yet absence of Bernal type graphitic stacking order), may inherit the exotic properties of rotated/slipped few-layer graphene (e.g., high flexibility and anisotropic transport properties). However, the fabrication of such a film remains challenging and unreported. Here we show that the annealing of reduced electrochemical graphene oxide (REGO), which has fewer in-plane defects than the conventional graphene oxide from Hummers’ method, leads to a nearly intact graphene lattice (Raman I D/I G down to 0.03) without restoring the graphitic stacking order (I 2D/I G > 1 and a single Lorentzian 2D peak). Atomic resolution transmission electron microscopy verifies the unique graphenic structure with random interlayer rotations. Density functional theory calculations imply the low defect density of REGO can suppress the interplanar interaction between undercoordinated carbon atoms, therefore inhibiting cross-plane migration of vacancies and the consequent establishment of stacking order. The annealed, graphenic REGO film is highly flexible and has an in-plane to cross-plane thermal conductivity ratio of 835 (among the highest reported for anisotropic thermal conductors). This high anisotropic ratio is attributed to the inhibited through-plane heat transport (0.26 W m −1 K −1) by the interlayer rotations and the high in-plane thermal conductivity (218 W m −1 K −1) enabled by intact graphene lattice. The graphenic films show high electromagnetic interference shielding effectiveness of 80.3 dB at a thickness of 53 μm and 42.4 dB at 5.7 μm, with an absolute effectiveness (>70000 dB cm 2 g −1) superior to two-dimensional metal carbides (MXenes) and Al foil.

Original languageEnglish
Article number118496
JournalCarbon
Volume215
Early online date2 Oct 2023
DOIs
Publication statusPublished - 1 Nov 2023

Keywords

  • Electrochemical graphene oxide
  • Electromagnetic interference shielding
  • Graphenization
  • Thermal conductivity
  • Vacancy migration

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