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-degrees-C, in addition to that desorbed below 1200-degrees-C (with a TPD peak at 980-degrees-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 low-temperature TPD peak is associated with oxygen chemisorbed on the graphite edge planes-{101lBAR} zigzag face and {112lBAR} 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.