Synthesis of and characterization of freestanding, high-hierarchically structured graphene-nanodiamond films

Publication date: 5 December 2017
Source:Materials & Design, Volume 135
Author(s): V.A. Yolshina, L.A. Yolshina, V.A. Elterman, E.G. Vovkotrub, A.A. Shatunova, V.I. Pryakhina, N.A. Khlebnikov, N.V. Tarakina
A novel carbon structure is synthesised during the interaction of solid organic precursors as d-glucose with a molten metallic zinc catalyst under a layer of molten alkali chlorides at air atmosphere. Scanning electronic microscopy studies show that the formed pure carbon film is non-isomorphic and smooth on one side, but highly evolved, with square steps, on the other. The Raman spectrum of the smooth side resembles that of multilayer graphene. The Raman spectrum of the developed side shows a typical sharp and narrow diamond peak at 1332cm⁻¹ along with graphene peaks. XPS data show that the most of the carbon atoms are at diamond sites. According to the results of an Auger spectroscopy investigation, obtained carbon film is composed of carbon atoms of sp² and sp³ hybridisation in a ratio of 1:1. From the average graphene cluster size of 5nm and average diamond crystal diameter of 2–7nm, it may be concluded that the formation of graphene-nanodiamond films in this system is thermodynamically possible at this temperature range without application of increased pressure. Chemically induced transition to the nanodiamond structure occurs in graphene layers due to presence of large quantities of atomic hydrogen in the molten salt media.

Graphical abstract

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