Studies on ultra-clean carbon surfaces—IV. Decomposition of carbon-oxygen surface complexes

Abstract

Graphon was first activated by preoxidation to 16.6 per cent weight loss at 625°C to introduce a desired amount of active surface area. Varying amounts of oxygen were then chemisorbed on this sample at 100°C by exposure to 0.10 Torr O 2. Following each chemisorption, the sample temperature was increased at a constant rate of 2°C/min to 950°C. Oxygen was released as CO and CO 2; these gases were allowed to remain in contact with the sample. The cumulative recovery of CO increases with increasing temperature. Recovery of CO 2, meanwhile, goes through a maximum because of its reaction at elevated temperatures with nascent carbon sites, produced primarily by the decomposition of the CO-producing complex. The plot of cumulative recovery of CO + CO 2 against temperature shows distinct linear regions, the amount recovered in each linear region showing close agreement with the amount of oxygen previously chemisorbed at different site configurations on the Graphon surface.