Spectroscopic evaluation of out-of-plane surface vibration bands from surface functionalization of graphite oxide by fluorination

The fluorination of graphite/graphite oxide (GO) and their derivatives has been widely investigated for how fluorine interacts with sp(2)/sp(3) carbon; however, the mechanism of this interaction has not yet been elucidated. Fluorination of GO (FGO) at either 10 or 15 psi for 24 h, produced two new absorption bands at, similar to 743 cm(-1) and 482 cm(-1), and are attributed to the presence of out-of-plane surface fluorine bonds in FGO (absent in fluorographite - FG). IR studies confirmed the stability of the formed C-F bonds and defect formation due to the introduction of oxyfluorinated species into the graphitic carbon through fluorination of epoxides. Fluorination of GO resulted in similar to 4-5 times more fluorine incorporation in bulk as compared to FG. (4.57 vs. 0.8 at.% and 6.64 vs. 1.4 at.% at 10 and 15 psi, respectively). PXRD analyses also showed that the interlayer spacing of FGO expanded in the presence of intercalated C-F species and a defect formation was observed with the evidence of increase of the I-D/I-G ratio from Raman spectra. To this end, understanding the origin of surface C-F bonds and structural changes in FGO therefore leads to new applications such as implementation of FGO for sensing, nano-electronics and energy storage. (C) 2014 Elsevier Ltd. All rights reserved.