These impurities could be due to the reagents used in the Hummers' method . Together with similar C:O ratios (Table , Supporting Information), the deconvolution of the high-resolution C1s and O1s spectra (Figure ) showed that the three GO materials had similar surface chemistry, dominated by the formation of C-O bonds characteristic of ethers and hydroxyls. The quantification of the deconvoluted components resulted in a slight lower relative abundance of oxygen atoms involved in C-O bonds in us-GO compared to l-GO (Figure ). This was accompanied by a slightly lower abundance of carbon atoms involved in C-O bonds; however it was not statistically significant.