科研之友
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摘要
Carbonaceous materials have been found to be active for the catalytic oxidation of NO into NO2 at room temperature, but the mechanism is unclear. Calculations based on density functional theory were employed to investigate the effects of hydroxyl and epoxy groups on the adsorption of NO, and then the oxidation to NO2. It is found that the surface hydroxyl groups of carbon materials can enhance the adsorption of NO. The enhancement is derived from a weak covalent interaction between the nitrogen atom of the NO molecule and the carbon surface. NO can be oxidized by epoxy groups with rather low barrier, which helps to explain the low temperature catalytic oxidation. The hydroxyl group possesses no significant effects on the oxidation barrier. The low oxidation barrier is ascribed to the unique electronic structure NO, the highest occupied molecular orbit (HOMO) of which is partially filled.
