| |
Records |
Links |
|
Author |
Schoeters, B.; Leenaerts, O.; Pourtois, G.; Partoens, B. |
|
| |
Title |
Ab-initio study of the segregation and electronic properties of neutral and charged B and P dopants in Si and Si/SiO2 nanowires |
Type |
A1 Journal article |
| |
Year |
2015 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
|
| |
Volume |
118 |
Issue |
118 |
Pages |
104306 |
|
| |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
|
| |
Abstract |
We perform first-principles calculations to investigate the preferred positions of B and P dopants, both neutral and in their preferred charge state, in Si and Si/SiO2 core-shell nanowires (NWs). In order to understand the observed trends in the formation energy, we isolate the different effects that determine these formation energies. By making the distinction between the unrelaxed and the relaxed formation energy, we separate the impact of the relaxation from that of the chemical environment. The unrelaxed formation energies are determined by three effects: (i) the effect of strain caused by size mismatch between the dopant and the host atoms, (ii) the local position of the band edges, and (iii) a screening effect. In the case of the SiNW (Si/SiO2 NW), these effects result in an increase of the formation energy away from the center (interface). The effect of relaxation depends on the relative size mismatch between the dopant and host atoms. A large size mismatch causes substantial relaxation that reduces the formation energy considerably, with the relaxation being more pronounced towards the edge of the wires. These effects explain the surface segregation of the B dopants in a SiNW, since the atomic relaxation induces a continuous drop of the formation energy towards the edge. However, for the P dopants, the formation energy starts to rise when moving from the center but drops to a minimum just next to the surface, indicating a different type of behavior. It also explains that the preferential location for B dopants in Si/SiO2 core-shell NWs is inside the oxide shell just next to the interface, whereas the P dopants prefer the positions next to the interface inside the Si core, which is in agreement with recent experiments. These preferred locations have an important impact on the electronic properties of these core-shell NWs. Our simulations indicate the possibility of hole gas formation when B segregates into the oxide shell. |
|
| |
Address |
|
|
| |
Corporate Author  |
|
Thesis |
|
|
| |
Publisher |
|
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Wos |
000361636900031 |
Publication Date |
2015-09-09 |
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0021-8979 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
| |
Impact Factor |
2.068 |
Times cited |
3 |
Open Access |
|
|
| |
Notes |
This work was carried out using the Turing HPC infrastructure at the CalcUA core facility of the Universiteit Antwerpen, a division of the Flemish Supercomputer Center VSC, funded by the Hercules Foundation, the Flemish government and the Universiteit Antwerpen. |
Approved |
Most recent IF: 2.068; 2015 IF: 2.183 |
|
| |
Call Number |
c:irua:128729 |
Serial |
4056 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Saqlain, M.A.; Hussain, A.; Siddiq, D.M.; Leenaerts, O.; Leitão, A.A. |
|
| |
Title |
DFT Study of Synergistic Catalysis of the Water-Gas-Shift Reaction on Cu-Au Bimetallic Surfaces |
Type |
A1 Journal article |
| |
Year |
2016 |
Publication |
ChemCatChem |
Abbreviated Journal |
Chemcatchem |
|
| |
Volume |
8 |
Issue |
8 |
Pages |
1208-1217 |
|
| |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
|
| |
Abstract |
The water-gas-shift reaction (WGSR) is an important industrial process that can be significantly enhanced at suitable catalyst surfaces. In this work, we investigate the catalytic behavior of metallic Cu(1 0 0) and bimetallic Cu–Au(1 0 0) surfaces. With density functional theory calculations, the variation in the Gibbs free energy (ΔG°), the activation barriers, and the rate constants for the WGSR are calculated. The variation in ΔG° for water dissociation shows that the process is spontaneous up to 520 K on the bimetallic surface and up to 229 K on the Cu(1 0 0) surface. The calculated rate constants for the process also show that the bimetallic surface is much more reactive than the Cu(1 0 0) surface. The calculated pressure–temperature phase diagram for water dissociation shows that the partial pressure of H2O required for water dissociation on the bimetallic surface is substantially lower than that on the Cu(1 0 0) surface at all the studied temperatures. Additionally, the calculations demonstrate that the kinetics of the water-gas-shift reaction is dominated by redox processes on both the surfaces. |
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
|
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Wos |
000373074900026 |
Publication Date |
2016-02-26 |
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
1867-3880 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
| |
Impact Factor |
4.803 |
Times cited |
8 |
Open Access |
|
|
| |
Notes |
; The authors would like to thank the Brazilian agencies CNPq, CAPES, FAPEMIG (CEX-PPM-00262/13), and TWAS for financial support and CENAPAD-SP for computational facilities. M.A. Saqlain pays special thanks to all the members of GFQSI for making his stay in Brazil memorable. ; |
Approved |
Most recent IF: 4.803 |
|
| |
Call Number |
c:irua:133236 |
Serial |
4070 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Kus, M.; Altantzis, T.; Vercauteren, S.; Caretti, I.; Leenaerts, O.; Batenburg, K.J.; Mertens, M.; Meynen, V.; Partoens, B.; Van Doorslaer, S.; Bals, S.; Cool, P. |
|
| |
Title |
Mechanistic Insight into the Photocatalytic Working of Fluorinated Anatase {001} Nanosheets |
Type |
A1 Journal article |
| |
Year |
2017 |
Publication |
The journal of physical chemistry: C : nanomaterials and interfaces |
Abbreviated Journal |
J Phys Chem C |
|
| |
Volume |
121 |
Issue |
121 |
Pages |
26275-26286 |
|
| |
Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT); Laboratory of adsorption and catalysis (LADCA) |
|
| |
Abstract |
Anatase nanosheets with exposed {001} facets
have gained increasing interest for photocatalytic applications. To
fully understand the structure-to-activity relation, combined
experimental and computational methods have been exploited.
Anatase nanosheets were prepared under hydrothermal conditions
in the presence of fluorine ions. High resolution scanning
transmission electron microscopy was used to fully characterize
the synthesized material, confirming the TiO2 nanosheet
morphology. Moreover, the surface structure and composition
of a single nanosheet could be determined by annular bright-field
scanning transmission electron microscopy (ABF-STEM) and
STEM electron energy loss spectroscopy (STEM-EELS). The photocatalytic activity was tested for the decomposition of organic
dyes rhodamine 6G and methyl orange and compared to a reference TiO2 anatase sample. The anatase nanosheets with exposed
{001} facets revealed a significantly lower photocatalytic activity compared to the reference. In order to understand the
mechanism for the catalytic performance, and to investigate the role of the presence of F−, light-induced electron paramagnetic
resonance (EPR) experiments were performed. The EPR results are in agreement with TEM, proving the presence of Ti3+
species close to the surface of the sample and allowing the analysis of the photoinduced formation of paramagnetic species.
Further, ab initio calculations of the anisotropic effective mass of electrons and electron holes in anatase show a very high effective
mass of electrons in the [001] direction, having a negative impact on the mobility of electrons toward the {001} surface and thus
the photocatalysis. Finally, motivated by the experimental results that indicate the presence of fluorine atoms at the surface, we
performed ab initio calculations to determine the position of the band edges in anatase slabs with different terminations of the
{001} surface. The presence of fluorine atoms near the surface is shown to strongly shift down the band edges, which indicates
another reason why it can be expected that the prepared samples with a large amount of {001} surface, but with fluorine atoms
near the surface, show only a low photocatalytic activity. |
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
|
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Wos |
000417228500017 |
Publication Date |
2017-11-30 |
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
1932-7447 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
| |
Impact Factor |
4.536 |
Times cited |
20 |
Open Access |
OpenAccess |
|
| |
Notes |
The authors acknowledge the University of Antwerp for financial support in the frame of a GOA project. S.B. acknowledges funding from the European Research Council under the Seventh Framework Program (FP7), ERC Grant No. 335078 COLOURATOM. S.V.D. and V.M. acknowledge funding from the Fund for Scientific Research-Flanders (G.0687.13). T.A. acknowledges financial support from the Research Foundation Flanders (FWO, Belgium) through a postdoctoral grant. (ROMEO:white; preprint:; postprint:restricted 12 months embargo; pdfversion:cannot); saraecas; ECAS_Sara; |
Approved |
Most recent IF: 4.536 |
|
| |
Call Number |
EMAT @ emat @c:irua:147240UA @ admin @ c:irua:147240 |
Serial |
4771 |
|
| Permanent link to this record |
