Density Functional Characterization of the Electronic Structure and Visible-Light Absorption of Cr-Doped Anatase TiO2

ChemPhysChem ◽  
2009 ◽  
Vol 10 (13) ◽  
pp. 2327-2333 ◽  
Author(s):  
Kesong Yang ◽  
Ying Dai ◽  
Baibiao Huang
Keyword(s):  
Electronic Structure ◽  
Visible Light ◽  
Light Absorption ◽  
Density Functional ◽  
Functional Characterization ◽  
Anatase Tio2 ◽  
Visible Light Absorption

scholarly journals Sensitization of Perovskite Strontium Stannate SrSnO3towards Visible-Light Absorption by Doping

2014 ◽  
Vol 2014 ◽  
pp. 1-3 ◽  
Author(s):  
Hungru Chen ◽  
Naoto Umezawa
Keyword(s):  
Solar Energy ◽  
Visible Light ◽  
Band Gap ◽  
Light Absorption ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Visible Light Absorption ◽  
Dopant Level ◽  
Strontium Stannate ◽  
Hybrid Density Functional

Perovskite strontium stannate SrSnO3is a promising photocatalyst. However, its band gap is too large for efficient solar energy conversion. In order to sensitize SrSnO3toward visible-light activities, the effects of doping with various selected cations and anions are investigated by using hybrid density functional calculations. Results show that doping can result in dopant level to conduction band transitions which lie lower in energy compared to the original band gap transition. Therefore, it is expected that doping SrSnO3can induce visible-light absorption.

Impact of surface hydroxylation in MgO-/SnO-nanocluster modified TiO2 anatase (101) composites on visible light absorption, charge separation and reducibility.

2017 ◽  
Author(s):  
Michael Nolan ◽  
Stephen Rhatigan
Keyword(s):  
Metal Oxide ◽  
Visible Light ◽  
Light Absorption ◽  
Charge Separation ◽  
Density Functional ◽  
Visible Range ◽  
Hydroxyl Groups ◽  
Visible Light Absorption ◽  
Tio2 Anatase ◽  
The Impact

Surface modification with metal oxide nanoclusters has emerged as a candidate for the enhancement of the photocatalytic activity of titanium dioxide. An increase in visible light absorption and the suppression of charge carrier recombination are necessary to improve the efficiency. We have studied Mg<sub>4</sub>O<sub>4</sub> and Sn<sub>4</sub>O<sub>4</sub> nanoclusters modifying the (101) surface of anatase TiO<sub>2</sub> using density functional theory corrected for on-site Coulomb interactions (DFT + U). Such studies typically focus on the pristine surface, free of the point defects and surface hydroxyls present in real surfaces. We have also examined the impact of partial hydroxylation of the anatase surface on a variety of outcomes such as nanocluster adsorption, light absorption, charge separation and reducibility. Our results indicate that the modifiers adsorb strongly at the surface, irrespective of the presence of hydroxyl groups, and that modification extends light absorption into the visible range while enhancing UV activity. Our model for the excited state of the heterostructures demonstrates that photoexcited electrons and holes are separated onto the TiO<sub>2</sub> surface and metal oxide nanocluster respectively. Comparisons with bare TiO<sub>2</sub> and other TiO<sub>2</sub>-based photocatalyst materials are presented throughout.<br>

Density functional theory calculations for the investigation of (Ag, N) codoping effect on the electronic and optical properties of anatase TiO2

2014 ◽  
Vol 28 (18) ◽  
pp. 1450112 ◽  
Author(s):  
Matiullah Khan ◽  
Wenbin Cao ◽  
Jing Li ◽  
Muhammad Iqbal Zaman ◽  
Abdul Manan
Keyword(s):  
Density Functional Theory ◽  
Visible Light ◽  
Band Gap ◽  
Light Absorption ◽  
Density Functional ◽  
Energy Calculation ◽  
Functional Theory ◽  
Visible Light Absorption ◽  
Defect Pair ◽  
N Doping

Efficient absorption of light in visible range and enhance separation of photoexcited electron-hole pairs (EHPs) are crucial for improving the photoactivity of metal nonmetal codoped TiO 2. By using density functional theory (DFT) calculations, an effective metal ( Ag ) and nonmetal ( N ) codoping approach is described to modify the photoelectrochemical properties of titanium dioxide ( TiO 2). Nitrogen (N) doping introduces isolated N -2p states above the valence band maximum (VBM) which acts as an electron trap to promote EHP recombination. For Ag -doped TiO 2, Ag -4d states are introduced above the VBM which leads to the band gap narrowing. Silver (Ag) and nitrogen codoped TiO 2 possess stable configuration, narrowed band gap and best visible light absorption. Defect pair binding energy calculation shows that individual dopants, located at a distance of 8.951 Å bind each other, which indicates that the defect pair is stable compared to the isolated impurities in the host lattice. Ag and N codoped TiO 2 shows better visible light absorption as compared to other doped models due to the reduced band gap. N doping reduces the band gap of TiO 2 while Ag doping enhances the EHPs separation, so their combined presence in a sample would improve the photocatalytic activity due to their synergistic codoping effect. Our calculations provide reasonable explanation for the experimental findings.

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