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.

FIRST-PRINCIPLES CALCULATIONS ON ELECTRONIC STRUCTURES OF TiO2 ANATASE (101) SURFACES WITH N IMPURITIES

2011 ◽  
Vol 25 (02) ◽  
pp. 119-129 ◽  
Author(s):  
QI LI CHEN ◽  
GUANG ZHENG ◽  
KAI HUA HE ◽  
BO LI
Keyword(s):  
Band Gap ◽  
Electronic Structures ◽  
Density Functional ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Tio2 Anatase ◽  
Exchange Correlation ◽  
N Doping ◽  
Band Gap Narrowing ◽  
Coefficient Method

The electronic structures of nitrogen ( N )-doped TiO 2 anatase (101) surfaces have been investigated by density functional theory (DFT) plane-wave pseudopotential method with general gradient approximation (GGA) + U (Hubbard coefficient) method being adopted to describe the exchange-correlation effects. Both substitutional and interstitial N doping have been considered in this paper as well as the case of surface N adsorption. The results demonstrated that there is no obvious band gap narrowing observed by introducing N impurities except several N 2p states lying in the gap, whereas the introduction of oxygen vacancy was confirmed playing an important role on band gap narrowing. The results accord well with some experimental results.

First-Principles Calculations on Pure and Ga-Doped Anatase TiO2

2010 ◽  
Vol 156-157 ◽  
pp. 1385-1388
Author(s):  
Rui Qing Xu ◽  
Lan Fang Yao ◽  
Lin Li ◽  
Shuo Wang ◽  
Lin Lin Tian ◽  
...  
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Density Functional ◽  
Correlation Energy ◽  
Anatase Tio2 ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Band Gap Narrowing

First-principles calculations using the plane-wave pseudo-potential (PWPP) method based on the density functional theory (DFT) is employed to study the crystal structure, band gap, density of states of anatase TiO2 doped with gadolinium (Gd). The generalized gradient approximation (GGA) based on exchange-correlation energy optimization is employed to calculate them. The calculated results demonstrate that the mixing of gadolinium dopants induces states with original titanium 3d and oxygen 2p valence band attributes to the band gap narrowing. This can enhance the photocatalytic activity of anatase TiO2.

First-Principles Calculations on Pure and Y-Doped Anatase TiO2

2013 ◽  
Vol 562-565 ◽  
pp. 1166-1170 ◽  
Author(s):  
Xiong Tang ◽  
Lan Fang Yao ◽  
Xin Pei Yan ◽  
Jun Long Kang
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Density Functional ◽  
Correlation Energy ◽  
Partial Density ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Calculation Results ◽  
Band Gap Narrowing

Using the First principles calculations, the crystal structure, band gap, total and partial density of states (DOS) of anatase TiO2and anatase TiO2doped with Yttrium were calculated by a plane-wave pseudopotential (PWPP) method based on density functional theory (DFT). The generalized gradient approximation (GGA) based on exchange-correlation energy optimization was employed to calculate them. From the calculation results, the band gap of anatase TiO2and Y3+doped TiO2are about 2.15eV and 0.86eV. The calculated results demonstrated that the mixing of Yttrium (Y) dopants induces states with original titanium 3d and oxygen 2p valence band attributes to the band gap narrowing. This can enhance the photocatalytic activity of anatase TiO2.

scholarly journals Dumbbell configuration of silicon adatom defects on silicene nanoribbons

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Huynh Anh Huy ◽  
Quoc Duy Ho ◽  
Truong Quoc Tuan ◽  
Ong Kim Le ◽  
Nguyen Le Hoai Phuong
Keyword(s):  
Magnetic Properties ◽  
Band Gap ◽  
Density Functional ◽  
Spin Moment ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
Electronic And Magnetic Properties ◽  
Spin Degeneracy ◽  
Silicene Nanoribbons ◽  
Formation Energies

AbstractUsing density functional theory (DFT), we performed theoretical investigation on structural, energetic, electronic, and magnetic properties of pure armchair silicene nanoribbons with edges terminated with hydrogen atoms (ASiNRs:H), and the absorptions of silicon (Si) atom(s) on the top of ASiNRs:H. The calculated results show that Si atoms prefer to adsorb on the top site of ASiNRs:H and form the single- and/or di-adatom defects depending on the numbers. Si absorption defect(s) change electronic and magnetic properties of ASiNRs:H. Depending on the adsorption site the band gap of ASiNRs:H can be larger or smaller. The largest band gap of 1 Si atom adsorption is 0.64 eV at site 3, the adsorption of 2 Si atoms has the largest band gap of 0.44 eV at site 1-D, while the adsorption at sites5 and 1-E turn into metallic. The formation energies of Si adsorption show that adatom defects in ASiNRs:H are more preferable than pure ASiNRs:H with silicon atom(s). 1 Si adsorption prefers to be added on the top site of a Si atom and form a single-adatom defect, while Si di-adatom defect has lower formation energy than the single-adatom and the most energetically favorable adsorption is at site 1-F. Si adsorption atoms break spin-degeneracy of ASiNRs:H lead to di-adatom defect at site 1-G has the highest spin moment. Our results suggest new ways to engineer the band gap and magnetic properties silicene materials.

scholarly journals First principles calculations on theoretical band gap improvement of IIIA-VA zinc-blende semiconductor InAs

2020 ◽  
Vol 31 (12) ◽  
pp. 2050178
Author(s):  
Waqas Mahmood ◽  
Arfan Bukhtiar ◽  
Muhammad Haroon ◽  
Bing Dong
Keyword(s):  
Band Gap ◽  
Density Functional ◽  
Local Density ◽  
Lattice Parameter ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Zinc Blende ◽  
Valence States ◽  
Direct Band ◽  
Experimental Findings

The structural, electronic, dielectric and vibrational properties of zinc-blende (ZB) InAs were studied within the framework of density functional theory (DFT) by employing local density approximation and norm-conserving pseudopotentials. The optimal lattice parameter, direct band gap, static dielectric constant, phonon frequencies and Born effective charges calculated by treating In-4d electrons as valence states are in satisfactory agreement with other reported theoretical and experimental findings. The calculated band gap is reasonably accurate and improved in comparison to other findings. This work will be useful for more computational studies related to semiconductor devices.

Computational study of Mg insertion into amorphous silicon: advantageous energetics over crystalline silicon for Mg storage

2013 ◽  
Vol 1540 ◽  
Author(s):  
Fleur Legrain ◽  
Oleksandr I. Malyi ◽  
Teck L. Tan ◽  
Sergei Manzhos
Keyword(s):  
Density Functional ◽  
Nearest Neighbor ◽  
Defect Formation ◽  
Crystalline Silicon ◽  
Computational Study ◽  
Binding Energies ◽  
Functional Theory ◽  
Wide Range ◽  
Insertion Sites ◽  
Formation Energies

ABSTRACTWe show in a theoretical density functional theory study that amorphous Si (a-Si) has more favorable energetics for Mg storage compared to crystalline Si (c-Si). Specifically, Mg and Li insertion is compared in a model a-Si simulation cell. Multiple sites for Mg insertion with a wide range of binding energies are identified. For many sites, Mg defect formation energies are negative, whereas they are positive in c-Si. Moreover, while clustering in c-Si destabilizes the insertion sites (by about 0.1/0.2 eV per atom for nearest-neighbor Li/Mg), it is found to stabilize some of the insertion sites for both Li (by up to 0.27 eV) and Mg (by up to 0.35 eV) in a-Si. This could have significant implications on the performance of Si anodes in Mg batteries.

Systematic first principles calculations of the effects of stacking faults defects on the 4H-SiC band structure

2010 ◽  
Vol 1246 ◽  
Author(s):  
Massimo Camarda ◽  
pietro delugas ◽  
Andrea Canino ◽  
Andrea Severino ◽  
nicolo piluso ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Stacking Faults ◽  
Perfect Crystal ◽  
First Principles Calculations ◽  
Electronic Band ◽  
Functional Theory ◽  
Experimental Findings ◽  
Electronic Band Structures ◽  
Formation Energies

AbstractShockley-type Stacking faults (SSF) in hexagonal Silicon Carbide polytypes have received considerable attention in recent years since it has been found that these defects are responsible for the degradation of forward I-V characteristics in p-i-n diodes. In order to extend the knowledge on these kind of defects and theoretically support experimental findings (specifically, photoluminescence spectral analysis), we have determined the Kohn-Sham electronic band structures, along the closed path Γ-M-K-Γ, using density functional theory. We have also determined the energies of the SSFs with respect to the perfect crystal finding that the (35) and (44) SSFs have unexpectedly low formation energies, for this reason we could expect these two defects to be easily generated/expanded either during the growth or post-growth process steps.

First-Principle Study of Effect of Strain on the Band Structure of Germanane Monolayer

2018 ◽  
Vol 787 ◽  
pp. 25-30
Author(s):  
Lei Liu ◽  
Yan Ju Ji ◽  
Yi Fan Liu
Keyword(s):  
Band Structure ◽  
Band Gap ◽  
First Principles ◽  
Density Functional ◽  
Catalytic Properties ◽  
Significant Implication ◽  
First Principle ◽  
First Principles Calculations ◽  
Biaxial Strain ◽  
Functional Theory

The effect of strain on the band structure of the GeH monolayer has been investigated by first-principles calculations based on density functional theory. The results show that the change of the band gap under the zigzag strain, the armchair strain and the biaxial strain is nonlinear. The effect of the biaxial strain on the band gap is the most obvious. In addition, the changes of energy under the three kinds of strain are asymmetric and the biaxial strain make the energy change the most. This work has significant implication of strain to tune optical catalytic properties of GeH monolayer.

Sign in / Sign up

Export Citation Format

Share Document