DO:10.1038/NMAT2858 SUPPLEMENTARY INFORMATION 3.0 GO-3L EDGE(-O-) 2.5 COOH,C-OH,C=O,C-O-C,C-O -×40 2.0 COOH,C-O,C-O-C* enhancement 1.5 C=O,COOH,C-O C=O COOH,C-O 0 C=O,COOH, C=O 11.0 玉 C=0,C-O,C00H* C-O,COOH/C=O* 0.5 0.0 Overlapped peak:minor contribution 075150225300375450525600675750825 900 Temperature(C) Supplementary Figure S4 Integrated absorbance vs.annealing temperature measured at 60C(GO with three layers).Each temperature is shown with a different color(60-850C from red to brown in sequence).The existing functional groups at each specific temperature are also ordered in terms of the area size.Almost all of the functional groups disappear at 500C and only C-O containing edge ether contribution remains thereafter.The peak at 800 cm indicates a maximum variation in dipole moment at 850C with a 40 times more enhancement compared to 750C.The standard deviations (s.d.0.1-3%)shown with error bars are obtained from the mean values of fluctuations in the values of total integrated areas.(*)Overlapped peak area with minor contribution from both COOH and C=O containing species. NATURE MATERIALS www.nature.com/naturematerialsnature materials | www.nature.com/naturematerials 7 doi: 10.1038/nmat2858 supplementary information 7                         °                               Supplementary Figure S4 Integrated absorbance vs. annealing temperature measured at 60°C (GO with three layers). Each temperature is shown with a different color (60-850°C from red to brown in sequence). The existing functional groups at each specific temperature are also ordered in terms of the area size. Almost all of the functional groups disappear at 500°C and only C-O containing edge ether contribution remains thereafter. The peak at 800 cm-1 indicates a maximum variation in dipole moment at 850°C with a 40 times more enhancement compared to 750°C. The standard deviations (s.d. 0.1-3%) shown with error bars are obtained from the mean values of fluctuations in the values of total integrated areas. (*) Overlapped peak area with minor contribution from both COOH and C=O containing species