O2 oxidation studies of the edge surface of graphite

✍ Scribed by Simon R. Kelemen; Howard Freund

• Publisher: Elsevier Science
• Year: 1985
• Tongue: English
• Weight: 742 KB
• Volume: 23
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(85)90221-0

✦ Synopsis

We have studied the reactive adsorption of 0, on the edge surface of graphite. At 300°C the efficiency of oxygen uptake showed a strong coverage-dependent reactive adsorption coefficient. In general, the efficiencies were low (< 10 ') over the majority of the coverage range. In contrast, the uptake of oxygen from Oz and H,O on sputter-damaged graphite was far more rapid. Sputter-damaged carbon surfaces exhibit greatly enhanced reactivity and are poor models of edge carbon activity. Thermal stability studies on the resultant oxidized edge graphite surfaces provide information about the encrgetics of product formation in gasification reactions. CO was the dominant product. A fraction of the oxygen on the surface is very tightly bound with energies greater than 85 kcallmole. The energy decreases to 70 kcal/mole over a wide coverage range. At the highest attainable coverages representing a small fractional population. the energy decreases further down to 58 kcal/mole. Our results show that increasing the amount of oxygen surface coverage decreases the energy barrier for gaseous CO formation but increases the barrier for O2 diswciation.