ZR. Yue et al./ Carbo37(1999)1785-17%6 XPS Valence Band C 2s 172749 160683 4235c/g 5300c/g 4240c/ AS-receivet M carbon fiber 1060c/g Fig. 6. FT-IR spectra of fiber versus extent of electrooxidation treated for 30 min under flowing nitrogen to learn more about the loss functional groups from the fibers by weight loss measurements as a function of temperature. The surface region to a depth of 50 A was probed by XPS after Adsorption of Ag and I, as a function of ting was also used to further probe the pore The weight losses obtained by heating electrochemi- cally-oxidized fibers at 550C under nitrogen for 30 min as Binding Energy(ev) a function of the original extent of oxidation are shown in Fig. 7. No significant weight loss from the as-received Fig. 5. High-resolution XPS valence band spectra of electro- fiber was detected after heating. However, electrochemical- chemically oxidized carbon fibers at different extents of oxidation ly oxidized carbon fibers exhibited weight losses after heating which increased with the extent of oxidation. To a significantly as electrochemical oxidation increased, in- first approximation weight loss was proportional to the dicating the quantity of C=o groups (ketone and/or extent of oxidation showing that the quantity of oxygen carboxyl groups) within the fibers increases with progres- functional groups was approximately proportional to the ive oxidation. The broad peak at about 1630 cm in the extent of electrooxidation. This agrees with NaoH uptake ectrum of the as-received fibers gradually shifts to about which is directly proportional to the extent of oxidation 1600 cm after 5648 C/g of oxidation. This broad peak over 4000 C/g [20] may be associated with a stretching vibrations of aromatics The weight loss of fibers oxidized to 5300 C/g. after (C=C)and/or the bending vibrations of physisorbed H,O. heating for 30 min under nitrogen is shown versus treatment temperature in Fig. 8. The magnitude of weight 3. 2. Heat treatment of electrochemically oxidised carbon loss depended strongly on treatment temperature. As the temperature was increased, the fiber weight loss increased continuously. This illustrates that different types of oxy- Electrochemically oxidized carbon fibers were heat gen-containing functions are present with different de-Z.R. Yue et al. / Carbon 37 (1999) 1785 –1796 1791 Fig. 6. FT-IR spectra of fiber versus extent of electrooxidation. treated for 30 min under flowing nitrogen to learn more about the loss functional groups from the fibers by weight loss measurements as a function of temperature. The ˚ surface region to a depth of 50 A was probed by XPS after 1 heating. Adsorption of Ag and I as a function of 2 heat-treating was also used to further probe the pore surface chemistry and structure. 3.2.1. Weight loss upon heating The weight losses obtained by heating electrochemi￾cally-oxidized fibers at 5508C under nitrogen for 30 min as a function of the original extent of oxidation are shown in Fig. 7. No significant weight loss from the as-received Fig. 5. High-resolution XPS valence band spectra of electro- fiber was detected after heating. However, electrochemical- chemically oxidized carbon fibers at different extents of oxidation. ly oxidized carbon fibers exhibited weight losses after heating which increased with the extent of oxidation. To a significantly as electrochemical oxidation increased, in- first approximation weight loss was proportional to the dicating the quantity of C5O groups (ketone and/or extent of oxidation showing that the quantity of oxygen carboxyl groups) within the fibers increases with progres- functional groups was approximately proportional to the 21 sive oxidation. The broad peak at about 1630 cm in the extent of electrooxidation. This agrees with NaOH uptake spectrum of the as-received fibers gradually shifts to about which is directly proportional to the extent of oxidation to 21 1600 cm after 5648 C/g of oxidation. This broad peak over 4000 C/g [20]. may be associated with a stretching vibrations of aromatics The weight loss of fibers oxidized to 5300 C/g, after (C5C) and/or the bending vibrations of physisorbed H O. heating for 30 min under nitrogen is shown versus 2 treatment temperature in Fig. 8. The magnitude of weight 3.2. Heat treatment of electrochemically oxidized carbon loss depended strongly on treatment temperature. As the fibers temperature was increased, the fiber weight loss increased continuously. This illustrates that different types of oxy￾Electrochemically oxidized carbon fibers were heat- gen-containing functions are present with different de-