The ATR-FTIR spectra are shown in Figure In the latter a hydroxyl O-H stretching peak at 3725 cm -1 [65] is also observed. The elemental composition of the GNPs was found from the XPS survey spectra displayed in Figure (g) and summarised in Table . The PG-10 and PG-CF elemental composition values have been reported previously . The C1s and O1s peaks can be seen in all three GNPs at 284 eV and 532 eV respectively, while a strong F1s peak can be observed in PG-CF at 688 eV, and a weak N1s peak in PG-NH at 399 eV. The oxygen content in PG-10 derives from oxygen passivated defects on the graphitic lattice. Exposure to CF4 plasma, leads to a ~5 at.% increase in fluorine content, at the expense of carbon content, while the oxygen content increases very slightly (+0.3 at.%). On the other hand, exposure to NH3 plasma more than doubles the oxygen content, while showing only a modest increase in nitrogen content. This suggests that the ionized NH3 gas is ineffective at adhering N modalities onto the carbon lattice or displacing existing oxygen groups.