First Principle Study of Na and P Co-Doped Heptazine Based Monolayer g-C3N4

2020 ◽  
Vol 978 ◽  
pp. 369-376
Author(s):  
Deepak K. Gorai ◽  
T.K. Kundu
Keyword(s):  
Density Functional ◽  
Light Response ◽  
Density Functional Theory Calculations ◽  
Molecular Orbitals ◽  
First Principle ◽  
Functional Theory ◽  
P Elements ◽  
Co Doping ◽  
Principle Density Functional Theory ◽  
Co Doped

Elements doping is a powerful way to alter the electronic structure and enhancing the photo catalytic activity of materials by relaxing the surrounding chemical bonds and forming new chemical bond. In this work, we have performed, the first principle density functional theory calculations to investigate the geometric, electronic and optical properties of pristine, Na-doped and P-doped as well as Na and P (Na/P) co-doped heptazine based monolayer graphitic carbon nitride (g-C3N4). The co-doping process results in significantly narrow band gap of g-C3N4. The optical absorption shows better visible-light response compare to pristine g-C3N4. After doping the highest occupied molecular orbitals (HOMO) and lowest unoccupied molecular orbitals (LUMO) show strong delocalization and indicates photo generated electron/hole (e-/h+) pair disunion abilities of doped systems are superior than pristine heptazine based monolayer g-C3N4. Thus the co-doping with Na and P elements is an effective technique to boost the photocatalytic performance of heptazine based monolayer g-C3N4.

A DFT Study of CO and NO Adsorptions on AlN-, AlP-, and ZnO-doped Graphene Nanosheets

2016 ◽  
Vol 230 (2) ◽  
Author(s):  
Niwat Promthong ◽  
Nadtanet Nunthaboot ◽  
Wanno Banchob
Keyword(s):  
Density Functional ◽  
Gas Adsorption ◽  
Graphene Nanosheets ◽  
Nitrogen Monoxide ◽  
Density Functional Theory Calculations ◽  
Pristine Graphene ◽  
Functional Theory ◽  
Co Doping ◽  
Doped Graphene ◽  
Co Doped

AbstractDensity functional theory calculations were performed to investigate the adsorption abilities of carbon monoxide (CO) and nitrogen monoxide (NO) gas molecules onto pristine graphene nanosheet (GNS), and AlN-, AlP-, and ZnO-doped GNSs. The co-doping of AlN, AlP, and ZnO onto GNS can improve the CO and NO adsorption abilities of GNS. The gas adsorption abilities on the pristine and co-doped GNSs were determined to be, in decreasing order: ZnO-GNS ∼ AlP-GNS > AlN-GNS > pristine GNSs and AlP-GNS > AlN-GNS > ZnO-GNS > pristine GNSs for the adsorptions of CO and NO, respectively. These newly developed co-doped GNSs could be candidates for CO and NO gas storages. The adsorption geometries, adsorption energies, density of states, and charge transfers were also reported.

scholarly journals Ab Initio Study of Ferroelectric Critical Size of SnTe Low-Dimensional Nanostructures

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 732 ◽  
Author(s):  
Takahiro Shimada ◽  
Koichiro Minaguro ◽  
Tao Xu ◽  
Jie Wang ◽  
Takayuki Kitamura
Keyword(s):  
Density Functional ◽  
Critical Size ◽  
Density Functional Theory Calculations ◽  
Cell Width ◽  
Functional Theory ◽  
Unit Cells ◽  
Principle Density Functional Theory ◽  
Low Dimensional ◽  
Insight Into ◽  
Ferroelectric Perovskite

Beyond a ferroelectric critical thickness of several nanometers existed in conventional ferroelectric perovskite oxides, ferroelectricity in ultimately thin dimensions was recently discovered in SnTe monolayers. This discovery suggests the possibility that SnTe can sustain ferroelectricity during further low-dimensional miniaturization. Here, we investigate a ferroelectric critical size of low-dimensional SnTe nanostructures such as nanoribbons (1D) and nanoflakes (0D) using first-principle density-functional theory calculations. We demonstrate that the smallest (one-unit-cell width) SnTe nanoribbon can sustain ferroelectricity and there is no ferroelectric critical size in the SnTe nanoribbons. On the other hand, the SnTe nanoflakes form a vortex of polarization and lose their toroidal ferroelectricity below the surface area of 4 × 4 unit cells (about 25 Å on one side). We also reveal the atomic and electronic mechanism of the absence or presence of critical size in SnTe low-dimensional nanostructures. Our result provides an insight into intrinsic ferroelectric critical size for low-dimensional chalcogenide layered materials.

scholarly journals Electronic Structure and Optical Properties of Co and Fe Doped ZnO

2016 ◽  
Vol 43 ◽  
pp. 23-28 ◽  
Author(s):  
Chun Ping Li ◽  
Ge Gao ◽  
Xin Chen
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Electronic Structures ◽  
Density Functional ◽  
Band Gaps ◽  
First Principle ◽  
Functional Theory ◽  
Doped Zno ◽  
Pseudo Potential ◽  
Co Doped

First-principle ultrasoft pseudo potential approach of the plane wave based on density functional theory (DFT) has been used for studying the electronic characterization and optical properties of ZnO and Fe, Co doped ZnO. The results show that the doping impurities change the lattice parameters a little, but bring more changes in the electronic structures. The band gaps are broadened by doping, and the Fermi level accesses to the conduction band which will lead the system to show the character of metallic properties. The dielectric function and absorption peaks are identified and the changes compared to pure ZnO are analyzed in detail.

scholarly journals Enhancement of Titania Photoanode Performance by Sandwiching Copper between Two Titania Layers

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4326
Author(s):  
Fan Yang ◽  
Ruizhuang Yang ◽  
Lin Yan ◽  
Jiankun Wu ◽  
Xiaolin Liu ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Sandwich Structure ◽  
Density Functional ◽  
Oxygen Vacancies ◽  
Light Response ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Tio2 Lattice ◽  
Novel Method ◽  
Cu Dopant

Vacancies in semiconductors can play a versatile role in boosting their photocatalytic activity. In this work, a novel TiO2/Cu/TiO2 sandwich structure is designed and constructed. Abundant vacancies were introduced in TiO2 lattice by Cu reduction under heat treatment. Meanwhile, Cu atom could diffuse into TiO2 to form Cu-doped TiO2. The synergistic effect between oxygen vacancies and Cu atoms achieved about 2.4 times improved photocurrent of TiO2/Cu/TiO2 sandwich structure compared to bare TiO2 thin film. The enhanced photoactivity may be attributed to regulated electron structure of TiO2 by oxygen vacancies and Cu dopant from experimental results and density functional theory calculations. Oxygen vacancies and Cu dopant in TiO2 formed through copper metal reduction can introduce impurity levels and narrow the band gap of TiO2, thus improve the visible light response. More importantly, the Cu2+ and oxygen vacancies in TiO2 lattice can dramatically increase the charge density around conduction band and promote separation of photo-induced charge carriers. Furthermore, the oxygen vacancies on the surface may serve as active site for sufficient chemical reaction. This work presents a novel method to prepare doped metal oxides catalysts with abundant vacancies for improving photocatalytic activity.

Bandgap control and optical properties of β-Si3N4 by single- and co-doping from a first-principles simulation

2018 ◽  
Vol 32 (14) ◽  
pp. 1850178 ◽  
Author(s):  
Xuefeng Lu ◽  
Xu Gao ◽  
Junqiang Ren ◽  
Cuixia Li ◽  
Xin Guo ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Formation Energy ◽  
Blue Shift ◽  
Functional Theory ◽  
Co Doping ◽  
Charge Density Difference ◽  
Co Doped

Bandgap tailoring of [Formula: see text]-Si3N4 is performed by single and co-doping by using density functional theory (DFT) of PBE functional and plane-wave pseudopotential method. The results reveal that a direct bandgap transfers into an indirect one when single-doped with As element. Also, a considerate decrease of bandgap to 0.221 eV and 0.315 eV is present for Al–P and As–P co-doped systems, respectively, exhibiting a representative semiconductor property that is characteristic for a narrower bandgap. Compared with other doped systems, Al-doped system with formation energy of 2.67 eV is present for a more stable structure. From charge density difference (CDD) maps, it is found that the blue area between co-doped atoms increases, illustrating an enhancement of covalent property for Al–P and Al–As bonds. Moreover, a slightly obvious “Blue shift” phenomenon can be obtained in Al, Al–P and Al–As doped systems, indicating an enhanced capacity of responses to light, which contributes to the insight for broader applications with regard to photoelectric devices.

scholarly journals Annealing effects on the structural and dielectric properties of (Nb + In) co-doped rutile TiO2 ceramics

RSC Advances ◽  
2019 ◽  
Vol 9 (15) ◽  
pp. 8364-8368 ◽  
Author(s):  
Lanling Zhao ◽  
Jun Wang ◽  
Zhigang Gai ◽  
Jichao Li ◽  
Jian Liu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Dielectric Properties ◽  
Electronic Structures ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Rutile Tio2 ◽  
Annealing Effects ◽  
Co Doped

Density functional theory calculations were conducted to investigate the electronic structures of rutile Ti16O32, Ti13Nb2InO32, and Ti13Nb2InO31 systems.

Vibrational spectra of alkylamino substituted phthalocyanine compounds: Density functional theory calculations

2018 ◽  
Vol 22 (09n10) ◽  
pp. 771-776 ◽  
Author(s):  
Xin Chen ◽  
Chiming Wang ◽  
Yuxiang Chen ◽  
Dongdong Qi ◽  
Jianzhuang Jiang
Keyword(s):  
Density Functional Theory ◽  
Infrared Spectra ◽  
Vibrational Spectra ◽  
Bond Order ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Molecular Orbitals ◽  
Functional Theory ◽  
Localized Molecular Orbitals ◽  
Theoretical Investigations

The infrared spectra of tetrakis(dibutylamino) phthalocyanine and octakis(dibutylamino) compounds were studied via theoretical investigations. The results reveal deep fusion of the peripheral alkylamino moieties with the phthalocyanine chromophore in the tetrakis(dibutylamino)- but not in the octakis(dibutylamino)-phthalocyanine compounds. The successive localized molecular orbitals (LMO) and bond order analyses give support for the infrared vibrational results.

First-principle study of SO2 adsorption on Fe/Co-doped vacancy defected single-walled (8, 0) carbon nanotubes in sensor applications

2019 ◽  
Vol 18 (05) ◽  
pp. 1950025 ◽  
Author(s):  
Meng Zhang ◽  
Guoqing Li ◽  
Xiaomin Lu ◽  
Qianru Zhang ◽  
Wei Li
Keyword(s):  
Carbon Nanotubes ◽  
Density Functional ◽  
Energy Gap ◽  
Single Vacancy ◽  
Functional Theory ◽  
Sensor Applications ◽  
Co Doping ◽  
So2 Adsorption ◽  
Before And After ◽  
Co Doped

To explore the excellent sensor for detecting the pollution gas [Formula: see text], the adsorptions of [Formula: see text] molecule on the surfaces of Fe/Co-doped carbon nanotubes (CNTs) and single vacancy defected (8, 0) CNTs were investigated by using density functional theory (DFT). In addition, the adsorption energies, geometries, energy gaps and electronic structures were analyzed. The results showed that Fe/Co-doping and single-vacancy-defected can improve the adsorption and sensitiveness of CNTs toward [Formula: see text]. Considering the changes of energy gap before and after the [Formula: see text] molecule adsorbed on each modified CNTs and its adsorption strength, Fe-doped CNTs (Fe-CNTs) and Co-doped site-2 single-vacancy-defected CNTs performed better for detecting [Formula: see text] molecule. With the decreasing number of electrons of the doped atom (Fe, Co, Ni), the adsorption became more stable. The results of this paper are profound and meaningful for designing [Formula: see text] sensing devices.

Band-gap tuning of graphene by Be doping and Be, B co-doping: a DFT study

RSC Advances ◽  
2015 ◽  
Vol 5 (69) ◽  
pp. 55762-55773 ◽  
Author(s):  
Saif Ullah ◽  
Akhtar Hussain ◽  
WaqarAdil Syed ◽  
Muhammad Adnan Saqlain ◽  
Idrees Ahmad ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
First Principles ◽  
Density Functional ◽  
Functional Theory ◽  
Co Doping ◽  
Structural And Electronic Properties ◽  
Doped Graphene ◽  
Band Gap Tuning ◽  
Co Doped

First-principles density functional theory (DFT) calculations were carried out to investigate the structural and electronic properties of beryllium (Be) doped and, Be with boron (B) co-doped graphene systems.

scholarly journals Strong Valence Electrons Dependent and Logical Relations of Elemental Impurities in 2D Binary Semiconductor: a Case of GeP3 Monolayer from Ab Initio Studies

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Suihao Zhang ◽  
Rui Li ◽  
Xiaonan Fu ◽  
Yu Zhao ◽  
Chunyao Niu ◽  
...  
Keyword(s):  
Density Functional ◽  
Logical Relation ◽  
Comprehensive Understanding ◽  
Electron Hole ◽  
Functional Theory ◽  
Group Iii ◽  
Co Doping ◽  
Elemental Impurities ◽  
Valence Electrons ◽  
Co Doped

Abstract Using first-principle calculations within density functional theory, we investigate the electronic property and stability of substitutionally doped 2D GeP3 monolayer with dopants from group III to VI. The conducting properties are found to be dramatically modified by both the doping sites and the number of valence electrons of dopants. Specifically, substitution on Ge site exhibits metal-semiconductor oscillations as a function of the number of valence electrons of dopants, while such oscillations are totally reversed when substitution on P site. Moreover, we also study the case of co-doping in GeP3, showing that co-doping can produce a logical “AND” phenomenon, that is, the conducting properties of co-doped GeP3 can be deduced via a simple logical relation according to the results of single doping. Finally, we investigate the formation energy of dopants and find that the electron-hole and hole-hole co-doped systems are much more energetically favorable due to the Coulomb attraction. Our findings not only present a comprehensive understanding of 2D doping phenomenon, but also propose an intriguing route to tune the electronic properties of 2D binary semiconductors.

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