Role of edge geometry and chemistry in the electronic properties of graphene nanostructures

2014 ◽  
Vol 173 ◽  
pp. 173-199 ◽  
Author(s):  
Shintaro Fujii ◽  
Maxim Ziatdinov ◽  
Misako Ohtsuka ◽  
Koichi Kusakabe ◽  
Manabu Kiguchi ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Atomic Scale ◽  
Strong Impact ◽  
Geometrical Shape ◽  
Vacancy Defects ◽  
Theoretical Simulation ◽  
Edge Geometry ◽  
Modified Graphene ◽  
Graphene Nanostructures

The geometry and chemistry of graphene nanostructures significantly affects their electronic properties. Despite a large number of experimental and theoretical studies dealing with the geometrical shape-dependent electronic properties of graphene nanostructures, experimental characterisation of their chemistry is clearly lacking. This is mostly due to the difficulties in preparing chemically-modified graphene nanostructures in a controlled manner and in identifying the exact chemistry of the graphene nanostructure on the atomic scale. Herein, we present scanning probe microscopic and first-principles characterisation of graphene nanostructures with different edge geometries and chemistry. Using the results of atomic scale electronic characterisation and theoretical simulation, we discuss the role of the edge geometry and chemistry on the electronic properties of graphene nanostructures with hydrogenated and oxidised linear edges at graphene boundaries and the internal edges of graphene vacancy defects. Atomic-scale details of the chemical composition have a strong impact on the electronic properties of graphene nanostructures,i.e., the presence or absence of non-bonding π states and the degree of resonance stability.

scholarly journals Photoelectrochemistry of Ferrites: Theoretical Predictions vs. Experimental Results

2020 ◽  
Vol 234 (4) ◽  
pp. 719-776 ◽  
Author(s):  
Anna C. Ulpe ◽  
Katharina C.L. Bauerfeind ◽  
Luis I. Granone ◽  
Arsou Arimi ◽  
Lena Megatif ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Electronic Properties ◽  
Absorption Spectra ◽  
Raman Spectra ◽  
First Principles ◽  
Experimental Results ◽  
Atomic Scale ◽  
Optical Absorption Spectra ◽  
Photoelectrochemical Activity

AbstractThis paper gives an overview about recent theoretical and experimental work on electronic and optical properties of spinel ferrites MFe2O4. These compounds have come into focus of research due to their possible application as photocatalyst material for photoelectrochemical water splitting. The theoretical background of state-of-the-art quantum-chemical approaches applied for predicting electronic and optical band gaps, absolute band positions, optical absorption spectra, dielectric functions and Raman spectra, is briefly reviewed. Recent applications of first-principles methods on magnetic and electronic properties of ferrites with M = Mg and the first row of subgroup elements Sc to Zn are presented, where it is shown that the fundamental band gap is strongly dependent on the spin state and the degree of inversion of the spinel structure. The observed variation of electronic properties may serve as an explanation for the large scattering of experimental results. The exchange of M and Fe cations has also a pronounced effect on the Raman spectra of ferrites, which is analyzed at atomic scale from first principles. Calculated optical absorption spectra of ferrites are compared to experimental spectra. The electronic nature of the first excitations and the role of oxygen vacancies are discussed. For the calculation of absolute band positions, which have a significant impact on the photoelectrochemical activity of the ferrites, models of the most stable ferrite surfaces are developed that take into account their polar nature and the interaction with the solvent. Theoretically predicted valence and conduction band edges are compared to results from electrochemical measurements. The role of cation exchange on the surface electronic structure is investigated both theoretically and experimentally.

scholarly journals Electronic Properties of WS2/WSe2 Heterostructure Containing Te Impurity: The Role of Substituting Position

2019 ◽  
Vol 18 (03n04) ◽  
pp. 1940007
Author(s):  
A. V. Krivosheeva ◽  
V. L. Shaposhnikov ◽  
V. E. Borisenko ◽  
J.-L. Lazzari
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Energy Band ◽  
Two Dimensional ◽  
Energy Band Gap ◽  
Theoretical Simulation ◽  
Impurity Position

An impact of positions of Te atoms substituting W atoms in two-dimensional WS2/WSe2 heterostructures on their electronic properties is investigated by theoretical simulation. The substitution of W by Te tends to reduce the energy band gap and can lead to metallic properties depending on the impurity position and concentration.

First principles study on energetic, structural, and electronic properties of defective g-C3N4-zz3 nanotubes

2014 ◽  
Vol 13 (04) ◽  
pp. 1450021 ◽  
Author(s):  
Seifollah Jalili ◽  
Farzad Molani ◽  
Jeremy Schofield
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Vacancy Defect ◽  
Vacancy Defects ◽  
Bond Rotation ◽  
Spin Polarized ◽  
Structural And Electronic Properties ◽  
Stabilization Energies

The energetic, electronic and structural properties of defective g- C 3 N 4-zz3 nanotubes are considered based on spin-polarized density-functional theory calculations. Nine basic system types with vacancy defects are characterized by their stabilization energies and band gaps. It is found that the nitrogen atom denoted as N 3 is the most favorable atom for a vacancy defect. In all cases, local bond reconstruction occurs in the presence of vacancy defects. The role of C / N bond rotations on the above properties has been also investigated. The results show that N 1– C 3 bond rotation is the most favorable rotational defect. In addition, the electronic properties of the semiconducting g- C 3 N 4-zz3 nanotube with defects have been studied using band structure and density of states plots.

Role of tip and edge geometry on vortex asymmetry

AIAA Journal ◽  
2001 ◽  
Vol 39 ◽  
pp. 539-543 ◽  
Author(s):  
T. Lim ◽  
K. B. Lua ◽  
S. C. Luo
Keyword(s):  
Edge Geometry

scholarly journals Ernst von Leyden (1832–1910): a pioneer in making oncology a respected medical discipline

2021 ◽  
Author(s):  
Peter Voswinckel ◽  
Nils Hansson
Keyword(s):  
International Association ◽  
German Society ◽  
Scientific Discipline ◽  
Strong Impact ◽  
Medical Discipline ◽  
History Of ◽  
National Socialists ◽  
New Research ◽  
German Physician

Abstract Purpose This article presents new research on the role of the renowned German physician Ernst von Leyden (1832–1910) in the emergence of oncology as a scientific discipline. Methods The article draws on archival sources from the archive of the German Society of Haematology and primary and secondary literature. Results Leyden initiated two important events in the early history of oncology: the first international cancer conference, which took place in Heidelberg, Germany, in 1906, and the founding of the first international association for cancer research (forerunner of today's UICC) in Berlin in 1908. Unfortunately, these facts are not mentioned in the most recent accounts. Both had a strong impact on the professionalization of oncology as a discipline in its own right. Conclusion Although not of Jewish origin, von Leyden was considered by the National Socialists to be “Jewish tainted”, which had a lasting effect on his perception at home and abroad.

Preponderant role of pentafluorophenyl moieties for tuning the electronic properties of extended benzodifuran-azomethine derivatives

2021 ◽  
Author(s):  
Chady Moussallem ◽  
Magali Allain ◽  
Frédéric Gohier ◽  
Pierre Frere
Keyword(s):  
Electronic Properties ◽  
Electron Donor ◽  
Electron Acceptor

From a central 3,7-bis(perfluorophenyl)-BDF unit, the extension performed with electron acceptor perfluorophenyl groups and/or electron donor N,N-dimethylamino groups via an imine link leads to symmetrical AAA and DAD or dissymmetrical...

scholarly journals The Unusual Role of Pro in Cu(II) Binding by His2-Cyclopentapeptide

2021 ◽  
Vol 22 (12) ◽  
pp. 6628
Author(s):  
Aleksandra Pieniężna ◽  
Aleksandra Kotynia ◽  
Justyna Brasuń
Keyword(s):  
Amino Acid ◽  
Potentiometric Titration ◽  
Amino Acid Residue ◽  
Strong Impact ◽  
Mononuclear Complexes ◽  
Study Results ◽  
Metal Ratio ◽  
Ph Range ◽  
L1 And L2

In this paper, we present findings from studying the interaction of copper(II) ions with the His2-cyclopentapeptide and the role of proline used for the purpose of potentiometric titration and UV-Vis, CD and EPR spectroscopic measurements. Experiments of two homodetic peptides differing by one amino acid residue were conducted for a ligand to metal ratio of 1:1 in the pH range 2.5–11.0. The presented studies reveal that peptides form only mononuclear complexes, and the CuH2L complex appears in the system first (for both L1 and L2). Study results show that the presence of Pro influences the structure of formed complexes and their stabilities and has a strong impact on the efficiency of copper(II) coordination.

Effects of Stone-Wales and vacancy defects in atomic-scale friction on defective graphite

2014 ◽  
Vol 104 (18) ◽  
pp. 183109 ◽  
Author(s):  
Xiao-Yu Sun ◽  
RunNi Wu ◽  
Re Xia ◽  
Xi-Hua Chu ◽  
Yuan-Jie Xu
Keyword(s):  
Atomic Scale ◽  
Vacancy Defects
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