Ozone Oxidation of Surface-Adsorbed Polycyclic Aromatic Hydrocarbons: Role of PAH−Surface Interaction

The heterogeneous chemistry of surface-adsorbed polycyclic aromatic hydrocarbons (PAHs) plays key roles in nanoscience, environmental science, and public health. Experimental evidence shows that the substrate can influence the heterogeneous oxidation of surface-bound PAHs, however, a mechanistic understanding of the role of the surface is still lacking. We examine the effects of the PAH−substrate interaction on the oxidation of surface-adsorbed anthracene, pyrene, and benzo[a]pyrene by ozone (O3) using density functional theory. We find that some O3 oxidation mechanisms for these planar PAH molecules lead to nonplanar intermediates or products, the formation of which may necessitate partial desorption or “lift-off” from a solid substrate. The energy penalty for partial desorption of each PAH from the surface is estimated for four different substrate types on the basis of literature data and accounted for in the thermodynamic analysis of the reaction pathways. We find that the attractive PAH−substrate inte...