Adsorption Mechanisms of Typical Carbonyl-Containing Volatile Organic Compounds on Anatase TiO₂ (001) Surface: A DFT Investigation

The carbonyl-containing compounds (CCs) are typical volatile organic compounds (VOCs) and ubiquitously present in the environment. Therefore, the adsorption structures and properties of typical CCs on the anatase TiO₂ (001) surface were investigated systematically with density functional theory (DFT) to understand their further catalytic degradation mechanisms. The adsorption mechanisms show that three selected typical CCs, acetaldehyde, acetone, and methyl acetate, can easily be trapped on the anatase TiO₂ (001) surface via the interaction between the carbonyl group with Ti_5c sites of catalyst surface. Especially for acetaldehyde with the bare carbonyl group and the strongest adsorption energy, it is the most stable on the surface, because the bare carbonyl group can interact with not only the Ti_5c atom, but also the O_2c atom of the surface. The substituent effect of different CCs has less impact on its adsorption models in this studied system and the bare carbonyl group is the key functional group within studied CCs. The Ti_5c atoms of anatase TiO₂ (001) surface are active sites to trap CCs. Our theoretical results are expected to provide insight into the adsorption mechanisms of these carbonyl-containing VOCs on TiO₂ catalyst and also to help understand the further catalytic degradation mechanisms of air pollutants at the molecular level