BET. theory was used to find the surface area and estimate layer numbers, it was carried out on a Quadrasorb EVO, the GNPs are outgassed (< 1 mbar, 150 C) for 24 hours prior to beginning the test, to remove residual moisture from the surface. Helium gas was used to calculate the dead volume and nitrogen gas as the adsorbate. The degree of exfoliation can be estimated by finding the 'layer number' (𝑛), from the specific surface area (SSA) using the formula: