Understanding the synergistic effects, optical and electronic properties of ternary Fe/C/S‐doped TiO₂ anatase within the DFT + U approach

Abstract

Although TiO2 is an efficient photocatalyst, its large band gap limits its photocatalytic activity only to the ultraviolet region. An experimentally synthesized ternary Fe/C/S‐doped TiO2 anatase showed improved visible light photocatalytic activity. However, a theoretical study of the underlying mechanism of the enhanced photocatalytic activity and the interaction of ternary Fe/C/S‐doped TiO2 has not yet been investigated. In this study, the defect formation energy, electronic structure and optical property of TiO2 doped with Fe, C, and S are investigated in detail using the density functional theory + U method. The calculated band gap (3.21 eV) of TiO2 anatase agree well with the experimental band gap (3.20 eV). The defect formation energy shows that the co‐ and ternary‐doped systems are thermodynamically favorable under oxygen‐rich condition. Compared to the undoped TiO2, the absorption edge of the mono‐, co‐, and ternary‐doped TiO2 is significantly enhanced in the visible light region. We have shown that ternary doping with C, S, and Fe induces a clean band structure without any impurity states. Moreover, the ternary Fe/C/S‐doped TiO2 exhibit an enhanced photocatalytic activity, a smaller band gap and negative formation energy compared to the mono‐ and co‐doped systems. Moreover, the band edges of Fe/C/S‐doped TiO2 align well with the redox potentials of water, which shows that the ternary Fe/C/S‐doped TiO2 is promising photocatalysts to split water into hydrogen and oxygen. These findings rationalize the available experimental results and can assist the design of TiO2‐based photocatalyst materials.

Computational Design of Novel Hydrogen-Doped, Oxygen-Deficient Monoclinic Zirconia with Excellent Optical Absorption and Electronic Properties

“…Furthermore, to analyze the electron-hole recombination rate, the relative ratio (D) of the electron effective mass to the hole effective mass was calculated using Eq. 6 37 . Larger than results in larger D, indicating less recombination of charge carriers and more mobility.…”

Group-IVA element-doped SrIn2O4 as potential materials for hydrogen production from water splitting with solar energy

“…Evidently, the D value of 27.83 for the pristine SrIn 2 O 4 implies the efficient separation of photogenerated charge carriers. The D values of the doped structures show a slight decrease; however, they are still several times higher than that of many typical photocatalytic materials, such as TiO 2 (0.97), 56 BiVO 4 (1.42), 57 and WS 2 (1.36). 57 Therefore, both the pristine and IVA-doped SrIn 2 O 4 are efficient photocatalysts with satisfactory photogenerated charge carrier recombination rates.…”

Recent advances in titanium dioxide/graphene photocatalyst materials as potentials of energy generation

“…However, the band structure, including the bandgap and the positions of VB and CB, is one of the important properties of a semiconductor because it Figure 1. The synergistic effect of photocatalytic titania [47].…”

“…In the TiO 2 lattice, the charge carriers may be captured as O − and Ti 3+ defect sites [45]. In some cases, the charge carriers may recombine to dissipate energy and eventually move to the catalyst surface to drive the redox reactions with the adsorbate (equation 2) [46,47].…”