La3+’s Effect on the Surface (101) of Anatase for Methylene Blue Dye Removal, a DFT Study

Abstract

Density functional theory (DFT) is a widely used method for studying matter at the quantum level. In this study, the surface (101) of TiO2 (anatase phase) was considered to develop DFT calculations and explain the effect of lanthanum ion (La3+) on the electronic properties, adsorption capacity, and photocatalytic activity of this semiconductor. Due to the presence of the La3+ ion, the bandgap energy value of La/TiO2 (2.98 eV) was lower than that obtained for TiO2 (3.21 eV). TDOS analysis demonstrated the presence of hybrid levels in La/TiO2 composed mainly of O2p and La5d orbitals. The chemical nature of the La-O bond was estimated from PDOS analysis, Bader charge analysis, and ELF function, resulting in a polar covalent type, due to the combination of covalent and ionic bonds. In general, the adsorption of the methylene blue (MB) molecule on the surface (101) of La/TiO2 was energetically more favorable than on the surface (101) of TiO2. The thermodynamic stability of doping TiO2 with lanthanum was deduced from the negative heat-segmentation values obtained. The evidence from this theoretical study supports the experimental results reported in the literature and suggests that the semiconductor La/TiO2 is a potential catalyst for applications that require sunlight.

Effect of Doping TiO2 NPs with Lanthanides (La, Ce and Eu) on the Adsorption and Photodegradation of Cyanide—A Comparative Study

“…In this study, the absorption threshold of the pristine TiO 2 (TO) semiconductor was around 350 nm. The strong absorption band observed in this region for TO would be associated with electronic transition from the valence band (VB) dominated by the 2p orbital of O to the conduction band (CB) dominated by the 3d orbital of Ti [ 35 ]. In contrast to the TO spectrum, the spectra of the nanoparticles that have been doped exhibit a red shift.…”

“…As can be seen, doping with lanthanide elements has demonstrated to be effective in adapting the TiO 2 surface to several applications [ 35 ]. However, almost surprisingly, no investigations have been found in the literature on use of TiO 2 doped with La, Ce, or Eu for adsorption and photocatalytic degradation of total cyanide in aqueous systems.…”

Understanding the prototype catalyst TiO2 surface with the help of density functional theory calculation

“…Seven dye-sensitizers 135 from the tetrahydroquinoline family were designed based on the structural attributes via quantitative structure-property relationship (QSPR) modeling. 140 DFT calculations of dye@TiO 2 interface indicate that all of them have optimal interfacial behavior. Bader charge, pDOS, charge density, and electrostatic potential difference calculations confirm that two of them are the most efficient dye-sensitizers, while the other five also possess the required properties to emerge as effective dye-sensitizers potentially better than those already utilized.…”

“…Studies on other dyes, including tetrahydroquinoline, 139 have also been carried out. Seven dye‐sensitizers from the tetrahydroquinoline family were designed based on the structural attributes via quantitative structure‐property relationship (QSPR) modeling 140 . DFT calculations of dye@TiO 2 interface indicate that all of them have optimal interfacial behavior.…”

Novel Semiconductor Cu(C3H3N3S3)3/ZnTiO3/TiO2 for the Photoinactivation of E. coli and S. aureus under Solar Light

“…Doping semiconductors with metal or non-metal ions is also a common method to reduce electron–hole recombination (e − /h + ) and extend the action of the photocatalyst against visible light. In relation to TiO 2 , which has a wide band gap (~3.2 eV), some effective dopants are mentioned, such as Au, Mo, Co, Rb, La, Ag, or Cu [ 40 , 41 , 42 ], which cause the band gap to decrease through the formation of defective states [ 43 ]. These states serve as active centers to trap electrons, limiting their mobility and increasing the separation of charge carriers [ 44 , 45 ].…”