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Topological and edge defects and misalignment of graphene layers in few-layer graphene strongly influence its chemical reactivity and thermal stability. Scanning and transmission electron microscopy and image analysis was used to determine alignment, degree of rotation, between layers in few-layer graphene prepared by decomposition of ethanol in microwave plasma torch at atmospheric pressure. The prepared nanosheets consisted of 1 to 20 layers, with interlayer distance of 0.34 nm, and the main structure was formed by successive growth of individual layers on top of each other. Using FFT, the edges and wrinkles were separated from the graphene layers themselves. The layers were spread out on each one separately and the angles of rotation between them were measured. The rotation angle between layer was from 20 to 30 degrees and the high quality graphene nanosheets, Raman bands 2D/G ratio of 1.6 and D/G ratio of 0.5, exhibited predominantly closed edges and opened edges were mostly found in the layers forming islands on the main structure. Graphene nanosheets remain fully stable in vacuum up to 1000 °C and thermogravimetric analysis showed complete burnout of the sample in synthetic air at 770 °C with more defective sample exhibiting higher weight loss between 400 and 700 °C.
Keywords: Graphene, edge structure, layer orientation, microwave plasma© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.