on the surface of GO was quantified by thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). Two main weight loss steps at temperatures above 100ºC were identified in the TGA curves (Figure ). In our measurements, the contribution of water corresponded to about 10% of the initial weight loss at temperatures below 100ºC. The first weight loss step occurred between 100ºC and 250ºC and is mainly credited to the release of combustion products of the more reactive functionalities such as the carboxyl and epoxy groups . The second weight loss step occurred between 250ºC and 470ºC, which describes the decomposition of more thermally stable groups such as carbonyls and hydroxyls, alongside the pyrolysis of residual carboxyls and ethers . No obvious differences in the functionalisation degree were identified by TGA (Figure ), as a similar first weight loss step of ~ 27% was obtained for all GO samples (Table , Supporting Information).