Journal
INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY
Volume 118, Issue 5, Pages -Publisher
WILEY
DOI: 10.1002/qua.25505
Keywords
DFT plus U method; formation energy; photocatalysis; TiO2 anatase; water splitting
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Funding
- Faculty of Science: University of Johannesburg, South Africa
- Centre for Nanomaterials and Science Research: Department of Applied Chemistry
- National Research Foundation [TTK14052167682]
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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.
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