The functionalisation degree obtained by TGA was similar for all three GO materials, which exhibited similar thermal stability (Figure and Table , Supporting Information). The first weight loss step (100ºC -250ºC) could be related to the greater content of carboxyl and epoxy groups , in agreement with the obtained FTIR spectra, where C-O and C=O bonds were expressed to a greater extent (Figure ). Epoxides are under strain due to the location of the oxygen atom out of the basal plane, and thus readily decomposed at high temperatures, generating hydroxyl groups . As a result, this reaction removes some carbon atoms from the graphene lattice, creating localised sp 3 defect states . However, thermal decomposition is a dynamic process, where the more reactive functionalities can be converted to others with lower thermodynamic energy. In this case, the generation of more stable functionalities such as hydroxyls should compensate the loss of epoxides and other ethers . As a result, a second weight loss step could still be identified (250ºC -470ºC) and could be attributed to residual hydroxyls, together with other more stable functionalities such as carbonyls and quinones .