锐钛矿相TiO2(101) 表面对有机分子不同官能团微观吸附的机制.

Volatile organic compounds (VOCs) seriously endanger the ecological environment and human health, so it is of great significance to detect VOCs gases with typical functional groups. In this paper, the sensing properties of VOCs gas C2H2, C2H4, HCOOH, CH3OH, HCHO and CH3COCH3 molecules with typical functional groups on the surface of anatase TiO2(101) were investigated. The results show that when the surface with oxygen vacancy defects adsorbs polar molecules, the larger the dipole moment is, the more stable the adsorption system is; when the surface with oxygen vacancy defects is adsorbed on non-polar molecules, the lower the saturation degree of C atom bonding, the more stable the adsorption system. The analysis shows that the differential charge density and charge layout reflect the influence of the size of the dipole moment and the degree of C atom bond saturation on the ability of gas molecules to gain or lose electrons. For polar molecules, the ability of the O atom in the functional group of the gas molecule to gain electrons is OCH3COCH3＞OHCHO＞OCH3OH＞OHCOOH. For non-polar molecules, the ability of the C atom in the functional group to gain electrons is CC2H2＞CC2H4.The analysis of the density of states diagram reveals that the peak position and size of the adsorption system at the Fermi energy level are also influenced by the dipole moment and the saturation of C atoms, which is essentially due to the different redox ability of different functional groups with the material surface. Therefore, the degree of adsorption stability on the surface of the material is closely related to the dipole moment of polar molecules or the degree of bond saturation of C atoms of non-polar molecules. It is of great significance to explore the adsorption gas sensing of organic gases by studying the dipole moment of the gas and the degree of C bond saturation. [ABSTRACT FROM AUTHOR]