Molecular adsorption properties of CH4 with noble metals doped onto oxygen vacancy defect of anatase TiO2 (101) surface: First-principles calculations

The adsorption properties of methane molecules (CH4) on the surface of noble metals doped anatase TiO2 (1 0 1) were studied using the first-principles method based on density functional theory (DFT). The noble metals M (M = Rh, Pd, Ag, Os, Ir, Pt and Au) are doped on the bridge oxygen vacancy defects of the anatase TiO2 surface, and the results show that the doping formation energy of Ir and Os are the lowest, -6.75 eV and -6.34 eV, respectively, indicating relatively stable systems. The adsorption energy analysis shows that both oxygen vacancy modification system and Os atom doping system can improve the stability of CH4 adsorption. By analyzing the density of state and charge density difference of the system, the orbital hybridization and charge transfer are verified the main reasons for the decrease of adsorption energy. The results show that Os atom doped TiO2 is a potential methane sensor material.