Fig. 2: GCF surface microstructures and grafting analysis.
a SEM image of GCF sideview morphology. The inset shows the GCF cross-section after FIB sampling. b HRTEM image of graphene-CF microstructure. c HRTEM image of the EELS acquisition map area of the graphene-CF interface (middle), estimated sp3 percentages (left) and bond lengths (right). The points shown in the HRTEM image are seven EELS acquisition positions (top three for graphene, one for interface, and bottom three for CF substrate). The distance between two adjacent points is 1 nm. d C K-edge XANES spectra of GCF sample, GCF fitting, SCF sample, SCF fitting and HOPG sample. SCF solid-flames-processed carbon fibre. HOPG highly-oriented pyrolytic graphite. e Nanoscratch testing lateral force versus displacement curve, SEM image and AFM morphological mapping. The yellow and blue dashed boxes shown in SEM and AFM image are the same acquisition area corresponding to the grey dash box in the nanoscratch load-displacement curve. f Root-mean-square displacement (RMSD) of sp2C and sp3C computed from MD grafting model with simulated stiffness to be 733 N m-1. g Calculated force constants for sp3C-sp3C, sp3C-sp2C, sp2C-sp2C bonding, and sp2 out-of-plane configuration. Blue atoms refer to sp3C and orange atoms refer to sp2C. Scale bars, 1 μm (a), 200 nm (a, inset), 5 nm (b), 1 nm (c), 2 μm (e).
