Abstract
Theoretically, lanthanum can bond with surface oxygens of ZnTiO(3) to form La-O-Ti bonds, resulting in the change of both the band structure and the electron state of the surface. To verify this statement, DFT calculations were performed using a model with a dispersed lanthanum atom on the surface (101) of ZnTiO(3). The negative heat segmentation values obtained suggest that the incorporation of La on the surface of ZnTiO(3) is thermodynamically stable. The bandgap energy value of La/ZnTiO(3) (2.92 eV) was lower than that of ZnTiO(3) (3.16 eV). TDOS showed that the conduction band (CB) and the valence band (VB) energy levels of La/ZnTiO(3) are denser than those of ZnTiO(3) due to the participation of hybrid levels composed mainly of O2p and La5d orbitals. From the PDOSs, Bader's charge analysis, and ELF function, it was established that the La-O bond is polar covalent. MB adsorption on La/ZnTiO(3) (-200 kJ/mol) was more favorable than on ZnTiO(3) (-85 kJ/mol). From the evidence of this study, it is proposed that the MB molecule first is adsorbed on the surface of La/ZnTiO(3), and then the electrons in the VB of La/ZnTiO(3) are photoexcited to hybrid levels, and finally, the MB molecule oxidizes into smaller molecules.