Eliminating the isolated states from the band structure of doped TiO2: A first principle study

2020 ◽  
Vol 34 (34) ◽  
pp. 2050388
Author(s):  
Matiullah Khan ◽  
Zeng Yi
Keyword(s):  
Band Structure ◽  
Visible Light ◽  
Fermi Level ◽  
Band Gap ◽  
Conduction Band ◽  
Light Absorption ◽  
Structure Modification ◽  
Visible Light Absorption ◽  
Oxidation Reduction ◽  
Clear Band

Band structure of anatase [Formula: see text] could be modified by doping foreign atoms. With ab-initio calculations, considering praseodymium, nitrogen and gadolinium as potential dopants, some mono-, co- and tri-doped models are introduced. The structure modification due to each model is compared with a standard [Formula: see text] system. Pr doping reduced the band gap of [Formula: see text] by introducing Pr 4f states below the conduction band, and the Fermi level appears below the conduction band minimum. The addition of nitrogen in Pr-doped [Formula: see text] pushed back the Fermi level to its intrinsic position while reducing the band gap. The tri-doped system comprising of Pr, N and Gd as dopants provided a populated band gap. The impurity states associated with Gd appeared in the middle of the band gap. The density of states analysis reveals that Pr 4f states change the location of N 2p states in the band structure. Instead of appearing as isolated states, the N 2p states are mixed with O 2p states while the Pr 4f states are coupled with the Ti 3d states in Pr, N-[Formula: see text]. The Pr, N, Gd tri-doped [Formula: see text] system provided strong visible light absorption due to the stepwise transition of electrons by Gd f states. While providing reasonable visible light absorption, the Pr, N-[Formula: see text] is expected to provide strong visible light photoactivity due to the clear band gap. Due to the absence of isolated states, the generated photo-excited carriers would be efficiently utilized in the oxidation/reduction processes.

Carrier Engineering of Zr-mediated Ta3N5 Film as Efficient Photoanode for Solar Water Splitting

2021 ◽  
Author(s):  
Xin Zou ◽  
Xueyang Han ◽  
Chengxiong Wang ◽  
Yunkun Zhao ◽  
Chun Du ◽  
...  
Keyword(s):  
Band Structure ◽  
Visible Light ◽  
Water Splitting ◽  
Light Absorption ◽  
Photoelectrochemical Water Splitting ◽  
Promising Candidate ◽  
Visible Light Absorption ◽  
Solar Water ◽  
Solar Water Splitting

Ta3N5 is regarded as a promising candidate material with adequate visible light absorption and band structure for photoelectrochemical water splitting. However, the performance of Ta3N5 is severely limited by the...

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.

Phosphorus- and fluorine-co-doped carbon nitride: modulated visible light absorption, charge carrier kinetics and boosted photocatalytic hydrogen evolution

2021 ◽  
Author(s):  
Pinnan Li ◽  
Mingya Wang ◽  
Shushu Huang ◽  
Yiguo Su
Keyword(s):  
Charge Carrier ◽  
Visible Light ◽  
Band Gap ◽  
Light Absorption ◽  
Carbon Nitride ◽  
Light Response ◽  
Visible Light Absorption ◽  
Visible Light Response ◽  
Band Gap Structure ◽  
Co Doped

A phosphorus and fluorine co-doped carbon nitride photocatalyst was constructed to modulate the band gap structure and visible light response ability of g-C3N4 as well as the photocatalytic H2 evolution activity.

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.

Highly efficient heterojunction solar cells enabled by edge-modified tellurene nanoribbons

2020 ◽  
Vol 22 (48) ◽  
pp. 28414-28422
Author(s):  
Yunzhi Gao ◽  
Kai Wu ◽  
Wei Hu ◽  
Jinlong Yang
Keyword(s):  
Solar Cells ◽  
Visible Light ◽  
Band Gap ◽  
Light Absorption ◽  
Carrier Mobility ◽  
Two Dimensional ◽  
Visible Light Absorption ◽  
Heterojunction Solar Cells ◽  
High Carrier Mobility ◽  
High Carrier

Tellurene, a two-dimensional (2D) semiconductor, meets the requirements for optoelectronic applications with desirable properties, such as a suitable band gap, high carrier mobility, strong visible light absorption and high air stability.

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