Trace (< 0.3%) Trace (< 0.3%) Trace (< 0.3%) X-ray diffraction (XRD) studies identified a pattern consistent with pure copper (fcc; Figure ), with no evidence of lattice strain induced by graphene incorporation. Both ML (Ni) and ML (Cu) coatings display a weak diffraction peak at ~26.4° relating to the (002) diffraction of the GnP nanosheets. This value is consistent with 2D-GnP, showing no evidence of interlayer expansion ). An XRD profile for the GnP-free ML (Ni) coating could not be obtained due to the fluorescence of the underlying steel from the Cu(kα) x-ray source.