Investigation of Mo-, Pt-, and Rh-doped rutile TiO2 based on first-principles calculations

In the present research, we use a first principles calculation to investigate the electronic structure and optical properties of Mo-, Pt- and Rh-doped rutile TiO2. The results indicate that the band gap of the Mo-, Pt-, and Rh-doped systems decreases to 1.758, 0.906, and 0.971 eV, respectively, compared with the 1.968 eV band gap of intrinsic TiO2, which is due to the hybridization of the doped atom d and O p orbital electrons, resulting in the formation of an impurity level and enhanced conductivity. The charge-difference density maps show that the covalence is enhanced in the region around Ti atoms for Mo- and Pt-doped systems, whereas Rh doping has little effect on the covalence. Based on these results, the bond population is 0.42, 0.28, and 0.27 for Mo–O, Pt–O, and Rh–O bonds, respectively. In the absorption spectrum, the peaks of the doped systems decrease significantly and redshift. Compared with the Mo-doped system, the Rh- and Pt-doped systems have lower static dielectric constant and dielectric l...