Strongly Bonded Oxygen in Graphite: Detection by High-Temperature TPD and Characterization

Temperature-programmed desorption (TPD) of oxidized graphites shows significant amounts of CO desorption at temperatures about 1200 °C, in addition to that desorbed below 1200 °C (with a TPD peak at 980 °C). The low-temperature peak has been reported in the literature for a variety of carbons, both graphitic and nongraphitic. X-ray photoelectron spectroscopy (XPS) and molecular orbital theory (MINDO) calculation results indicate that the lowjtemperature TPD peak is associated with oxygen chemisorbed on the graphite edge planes-{101̄1} zigzag face and {112̄1} armchair face-with an XPS O(1s) binding energy of 533 eV, and that the high-temperature TPD peak is associated with oxygen atoms intercalated between basal planes with an XPS O(1s) binding energy of 531.2 eV.