Adsorption mechanism of typical oxygen, sulfur, and chlorine containing VOCs on TiO2 (0 0 1) surface: First principle calculations

Abstract The photocatalytic degradation of volatile organic compounds has been gaining much interest in recent years to solve the long-standing problem of indoor air pollution. For this purpose, anatase TiO2 and its derivatives are regarded as potential photocatalyst materials. Thus, we study the adsorption mechanism of selected volatile organic compounds such as formaldehyde, methyl chloride, and carbon disulfide on TiO2 (0 0 1) surface using first principle calculations to comprehend their surface interaction and catalytic degradation in depth. The study suggests that formaldehyde interacts with TiO2 (0 0 1) surface through chemical bonds that form a saddle-like structure exhibiting a high adsorption energy value (0.543 eV). It can be inferred that the fivefold coordinated Ti5c and twofold coordinated O2c atoms are the only adsorption sites on TiO2 (0 0 1) surface. However, significant variations are observed for chloride and sulfur containing groups. For instance, the methyl chloride and carbon disulfide physisorbed on the surface of TiO2 (0 0 1) without any chemical bond formation exhibits low adsorption energy values. The results are further confirmed by calculating the corresponding density of states, and electron density differences in all cases. This study provides a detailed investigation of various VOCs on the surface of TiO2 (0 0 1), which provides further insight into the construction of photocatalytic materials for the photodegradation of VOCs.