scholarly journals Mechanisms of Visible Light Photocatalysis in N-Doped Anatase TiO2with Oxygen Vacancies from GGA+U Calculations

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Hsuan-Chung Wu ◽  
Yu-Siang Lin ◽  
Syuan-Wei Lin
Keyword(s):  
Visible Light ◽  
Band Gap ◽  
Density Functional ◽  
Nitrogen Doping ◽  
Formation Energy ◽  
Oxygen Vacancies ◽  
Energy Charge ◽  
Visible Light Photocatalysis ◽  
Donor States ◽  
Band Gap Narrowing

We have systematically studied the photocatalytic mechanisms of nitrogen doping in anatase TiO2using first-principles calculations based on density functional theory, employing HubbardU(8.47 eV) on-site correction. The impurity formation energy, charge density, and electronic structure properties of TiO2supercells containing substitutional nitrogen, interstitial nitrogen, or oxygen vacancies were evaluated to clarify the mechanisms under visible light. According to the formation energy, a substitutional N atom is better formed than an interstitial N atom, and the formation of an oxygen vacancy in N-doped TiO2is easier than that in pure TiO2. The calculated results have shown that a significant band gap narrowing may only occur in heavy nitrogen doping. With light nitrogen doping, the photocatalysis under visible light relies on N-isolated impurity states. Oxygen vacancies existence in N-doped TiO2can improve the photocatalysis in visible light because of a band gap narrowing and n-type donor states. These findings provide a reasonable explanation of the mechanisms of visible light photocatalysis in N-doped TiO2.

scholarly journals Band Gap Tuning of Photo Fenton-like Fe3O4/C Catalyst through Oxygen Vacancies for Advanced Visible Light Photocatalysis

2021 ◽  
Author(s):  
Muthaimanoj Periyasamy ◽  
Sumanta Sain ◽  
Moumi Mandal ◽  
Utsav Sengupta ◽  
Sudipta Mukhopadhyay ◽  
...  
Keyword(s):  
Visible Light ◽  
Band Gap ◽  
Iron Ore ◽  
Oxygen Vacancies ◽  
Reduction Method ◽  
Low Cost ◽  
Visible Light Photocatalysis ◽  
Iron Precursor ◽  
Band Gap Tuning ◽  
Hydrothermal Reduction

In this contribution, low-cost Fe3O4/C nanocomposites has been targeted by a simplistic single-pot D-glucose mediated hydrothermal reduction method using a single iron precursor (FeCl3. 6H2O) acquired from accumulated iron ore...

Synergistic effects on band gap-narrowing in titania by doping from first-principles calculations: density functional theory studies

2011 ◽  
Vol 1352 ◽  
Author(s):  
Run Long ◽  
Niall J. English
Keyword(s):  
Visible Light ◽  
Band Gap ◽  
Density Functional ◽  
Synergistic Effects ◽  
Theoretical Calculations ◽  
Binding Energies ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Band Gap Narrowing ◽  
Formation Energies

ABSTRACTThe large intrinsic band gap in TiO2 has hindered severely its potential application for visible-light irradiation. We have used a passivated approach to modify the band edges of anatase-TiO2 by codoping of X (N, C) with transition metals (TM=W, Re, Os) to extend the absorption edge to longer visible-light wavelengths. It was found that all the codoped systems can narrow the band gap significantly; in particular, (N+W)-codoped systems could serve as remarkably better photocatalysts with both narrowing of the band gap and relatively smaller formation energies and larger binding energies than those of (C+TM) and (N+TM)-codoped systems. Our theoretical calculations help to rationalise experimental results and provide reasonably meaningful guides for experiment to develop more powerful visible-light photocatalysts.

scholarly journals On the Effects of Doping on the Catalytic Performance of (La,Sr)CoO3. A DFT Study of CO Oxidation

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 312 ◽  
Author(s):  
Antonella Glisenti ◽  
Andrea Vittadini
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Formation Energy ◽  
Oxygen Vacancies ◽  
Catalytic Performance ◽  
Energy Profiles ◽  
High Concentrations ◽  
3D Impurities

The effects of modifying the composition of LaCoO3 on the catalytic activity are predicted by density functional calculations. Partially replacing La by Sr ions has benefical effects, causing a lowering of the formation energy of O vacancies. In contrast to that, doping at the Co site is less effective, as only 3d impurities heavier than Co are able to stabilize vacancies at high concentrations. The comparison of the energy profiles for CO oxidation of undoped and of Ni-, Cu-m and Zn-doped (La,Sr)CoO3(100) surface shows that Cu is most effective. However, the effects are less spectacular than in the SrTiO3 case, due to the different energetics for the formation of oxygen vacancies in the two hosts.

scholarly journals Band gap tuning of lead-substituted BaSnO3 for visible light photocatalysis

2007 ◽  
Vol 90 (3) ◽  
pp. 034103 ◽  
Author(s):  
Pramod H. Borse ◽  
Upendra A. Joshi ◽  
Sang Min Ji ◽  
Jum Suk Jang ◽  
Jae Sung Lee ◽  
...  
Keyword(s):  
Visible Light ◽  
Band Gap ◽  
Visible Light Photocatalysis ◽  
Band Gap Tuning

Structural and Electronic Properties of Oxygen Vacancies in Monoclinic HfO2

2007 ◽  
Vol 996 ◽  
Author(s):  
Peter Broqvist ◽  
Alfredo Pasquarello
Keyword(s):  
Oxygen Vacancy ◽  
Optical Absorption ◽  
Total Energy ◽  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Oxygen Vacancies ◽  
Structural And Electronic Properties ◽  
Defect Levels ◽  
Hybrid Density Functional

AbstractWe study structural and electronic properties of the oxygen vacancy in monoclinic HfO2 for five different charge states. We use a hybrid density functional to accurately reproduce the experimental band gap. To compare with measured defect levels, we determine total-energy differences appropriate to the considered experiments. Our results show that the oxygen vacancy can consistently account for the defect levels observed in optical absorption, direct electron injection, and trap-assisted conduction experiments.

THE EFFECT OF HIGH N-DOPED ANATASE TiO2 ON THE BAND GAP NARROWING AND REDSHIFT BY FIRST-PRINCIPLES

2012 ◽  
Vol 26 (27) ◽  
pp. 1250179 ◽  
Author(s):  
QINGYU HOU ◽  
YONGJUN JIN ◽  
CHUN YING ◽  
ERJUN ZHAO ◽  
YUE ZHANG ◽  
...  
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Formation Energy ◽  
Doping Concentration ◽  
Covalent Bond ◽  
Anatase Tio2 ◽  
Structure Population ◽  
Densities Of States ◽  
N Doping ◽  
Band Gap Narrowing

Anatase TiO 2 supercells were studied by first-principles, in which one was undoped and another three were high N -doping. Partial densities of states, band structure, population and absorption spectrum were calculated. The calculated results indicated that in the condition of TiO 2-x N x (x = 0.0625, 0.125, 0.25), the higher the doping concentration is, the shorter will be the lattice parameters parallel to the direction of c-axis. The strength of covalent bond significantly varied. The formation energy increases at first, and then decreases. The doping models become less stable as N -doping concentration increases. Meanwhile, the narrower the band gap is, the more significant will be the redshift, which is in agreement with the experimental results.

Realization of Visible Light Photocatalysis by Wide Band Gap Pure SnO 2 and Study of In 2 O 3 Sensitization Porous SnO 2 Photolysis Catalyst

2019 ◽  
Vol 4 (29) ◽  
pp. 8460-8469 ◽  
Author(s):  
Li Peng ◽  
Yang Xiao ◽  
Xiao‐li Wang ◽  
Da‐wei Feng ◽  
Hui Yu ◽  
...  
Keyword(s):  
Visible Light ◽  
Band Gap ◽  
Wide Band ◽  
Visible Light Photocatalysis ◽  
Wide Band Gap
Sign in / Sign up

Export Citation Format

Share Document