Special Issue "Modeling of Complex Interfaces: From Surface Chemistry to Nano Chemistry"

A special issue of Nanomaterials (ISSN 2079-4991).

Deadline for manuscript submissions: closed (15 April 2019).

Special Issue Editor

Prof. Dr. Frederik Tielens
Website
Guest Editor
Faculteit Wetenschappen en Bio-ingenieurswetenschappen, Vrije Universiteit Brussel, B-1050 Brussel, Belgium
Interests: density functional theory (DFT); silica-based materials; noble metals; bio- and biological materials; theoretical chemistry; computational chemistry; materials characterization at the atomic/molecular level

Special Issue Information

Dear Colleagues,

For a few years, quantum chemical modeling of materials has experienced a tremendous boost, which is in line with the available computational power. However, Moore’s law being respected or not, the difficulty of modeling is now shifted to the construction of the model itself. Of course, the accuracy of the calculations can be still be improved, but the main chemical properties and their trends are relatively well reproduced nowadays. One can say that DFT is now at a mature age and that it can be used as a reliable prediction tool in material science applications. Nevertheless, DFT is especially efficient describing chemical phenomena at the molecular level, the systems studied increases continuously in size and complexity. The size of the system is directly related to the computation power, and the complexity is related to the quality of the calculation method and the representation of the chemical environment in the model. It is the latter property that brings the computational chemist’s chemical intuition and general chemistry knowledge the forefront. In this Special Issue we want to focus on the construction of pertinent models that are able to describe and predict as accurately as possible with available computational power, the chemistry of materials.

Prof. Dr. Frederik Tielens
Guest Editor

Manuscript Submission Information

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Keywords

  • DFT
  • Surface Science
  • Heterogenous Catalysis(oxides, metals, biological minerals)
  • Adsorption
  • Electrochemistry
  • Self Assembled Monolayers
  • Solid/Liquid interface

Published Papers (11 papers)

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Editorial

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Open AccessEditorial
Modeling of Complex Interfaces: From Surface Chemistry to Nano Chemistry
Nanomaterials 2020, 10(3), 540; https://doi.org/10.3390/nano10030540 - 17 Mar 2020
Abstract
For a few years now, quantum chemical modeling of materials has experienced a tremendous boost due to the increasing computational power [...] Full article

Research

Jump to: Editorial

Open AccessArticle
Computational Modeling of Tensile Stress Effects on the Structure and Stability of Prototypical Covalent and Layered Materials
Nanomaterials 2019, 9(10), 1483; https://doi.org/10.3390/nano9101483 - 18 Oct 2019
Cited by 1
Abstract
Understanding the stability limit of crystalline materials under variable tensile stress conditions is of capital interest for technological applications. In this study, we present results from first-principles density functional theory calculations that quantitatively account for the response of selected covalent and layered materials [...] Read more.
Understanding the stability limit of crystalline materials under variable tensile stress conditions is of capital interest for technological applications. In this study, we present results from first-principles density functional theory calculations that quantitatively account for the response of selected covalent and layered materials to general stress conditions. In particular, we have evaluated the ideal strength along the main crystallographic directions of 3C and 2H polytypes of SiC, hexagonal ABA stacking of graphite and 2H-MoS 2 . Transverse superimposed stress on the tensile stress was taken into account in order to evaluate how the critical strength is affected by these multi-load conditions. In general, increasing transverse stress from negative to positive values leads to the expected decreasing of the critical strength. Few exceptions found in the compressive stress region correlate with the trends in the density of bonds along the directions with the unexpected behavior. In addition, we propose a modified spinodal equation of state able to accurately describe the calculated stress–strain curves. This analytical function is of general use and can also be applied to experimental data anticipating critical strengths and strain values, and for providing information on the energy stored in tensile stress processes. Full article
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Open AccessArticle
Understanding the Role of Rutile TiO2 Surface Orientation on Molecular Hydrogen Activation
Nanomaterials 2019, 9(9), 1199; https://doi.org/10.3390/nano9091199 - 26 Aug 2019
Cited by 4
Abstract
Titanium oxide (TiO2) has been widely used in many fields, such as photocatalysis, photovoltaics, catalysis, and sensors, where its interaction with molecular H2 with TiO2 surface plays an important role. However, the activation of hydrogen over rutile TiO2 [...] Read more.
Titanium oxide (TiO2) has been widely used in many fields, such as photocatalysis, photovoltaics, catalysis, and sensors, where its interaction with molecular H2 with TiO2 surface plays an important role. However, the activation of hydrogen over rutile TiO2 surfaces has not been systematically studied regarding the surface termination dependence. In this work, we use density functional theory (PBE+U) to identify the pathways for two processes: the heterolytic dissociation of H2 as a hydride–proton pair, and the subsequent H transfer from Ti to near O accompanied by reduction of the Ti sites. Four stoichiometric surface orientations were considered: (001), (100), (110), and (101). The lowest activation barriers are found for hydrogen dissociation on (001) and (110), with energies of 0.56 eV and 0.50 eV, respectively. The highest activation barriers are found on (100) and (101), with energies of 1.08 eV and 0.79 eV, respectively. For hydrogen transfer from Ti to near O, the activation barriers are higher (from 1.40 to 1.86 eV). Our results indicate that the dissociation step is kinetically more favorable than the H transfer process, although the latter is thermodynamically more favorable. We discuss the implications in the stability of the hydride–proton pair, and provide structures, electronic structure, vibrational analysis, and temperature effects to characterize the reactivity of the four TiO2 orientations. Full article
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Open AccessArticle
Dibenzyl Disulfide Adsorption on Cationic Exchanged Faujasites: A DFT Study
Nanomaterials 2019, 9(5), 715; https://doi.org/10.3390/nano9050715 - 08 May 2019
Cited by 3
Abstract
Although dibenzyl disulfide (DBDS) is used as a mineral oil stabilizer, its presence in electrical transformer oil is associated as one of the major causes of copper corrosion and subsequent formation of copper sulfide. In order to prevent these undesirable processes, MY zeolites [...] Read more.
Although dibenzyl disulfide (DBDS) is used as a mineral oil stabilizer, its presence in electrical transformer oil is associated as one of the major causes of copper corrosion and subsequent formation of copper sulfide. In order to prevent these undesirable processes, MY zeolites (with M = Li, Na, K, Cs, Cu or Ag) are proposed to adsorb molecularly DBDS. In this study, different MY zeolites are investigated at the DFT+D level in order to assess their ability in DBDS adsorption. It was found that CsY, AgY and CuY exhibit the best compromise between high interaction energies and limited S-S bond activation, thus emerging as optimal adsorbents for DBDS. Full article
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Open AccessArticle
Thermal Boundary Characteristics of Homo-/Heterogeneous Interfaces
Nanomaterials 2019, 9(5), 663; https://doi.org/10.3390/nano9050663 - 26 Apr 2019
Cited by 2
Abstract
The interface of two solids in contact introduces a thermal boundary resistance (TBR), which is challenging to measure from experiments. Besides, if the interface is reactive, it can form an intermediate recrystallized or amorphous region, and extra influencing phenomena are introduced. Reactive force [...] Read more.
The interface of two solids in contact introduces a thermal boundary resistance (TBR), which is challenging to measure from experiments. Besides, if the interface is reactive, it can form an intermediate recrystallized or amorphous region, and extra influencing phenomena are introduced. Reactive force field Molecular Dynamics (ReaxFF MD) is used to study these interfacial phenomena at the (non-)reactive interface. The non-reactive interfaces are compared using a phenomenological theory (PT), predicting the temperature discontinuity at the interface. By connecting ReaxFF MD and PT we confirm a continuous temperature profile for the homogeneous non-reactive interface and a temperature jump in case of the heterogeneous non-reactive interface. ReaxFF MD is further used to understand the effect of chemical activity of two solids in contact. The selected Si/SiO2 materials showed that the TBR of the reacted interface is two times larger than the non-reactive, going from 1.65 × 10 9 to 3.38 × 10 9 m2K/W. This is linked to the formation of an intermediate amorphous layer induced by heating, which remains stable when the system is cooled again. This provides the possibility to design multi-layered structures with a desired TBR. Full article
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Open AccessArticle
Investigation of the Impact of Cross-Polymerization on the Structural and Frictional Properties of Alkylsilane Monolayers Using Molecular Simulation
Nanomaterials 2019, 9(4), 639; https://doi.org/10.3390/nano9040639 - 19 Apr 2019
Cited by 4
Abstract
Cross-linked chemisorbed n-alkylsilane (CH3(CH2)n−1Si(OH)3) monolayers on amorphous silica surfaces have been studied and their structural properties and frictional performance were compared to those of equivalent monolayers without cross-linkages. The simulations isolated for the [...] Read more.
Cross-linked chemisorbed n-alkylsilane (CH3(CH2)n−1Si(OH)3) monolayers on amorphous silica surfaces have been studied and their structural properties and frictional performance were compared to those of equivalent monolayers without cross-linkages. The simulations isolated for the first time the effects of both siloxane cross-linkages and the fraction of chains chemisorbed to the surface, providing insight into a longstanding fundamental question in the literature regarding molecular-level structure. The results demonstrate that both cross-linkages and the fraction of chemisorbed chains affect monolayer structure in small but measurable ways, particularly for monolayers constructed from short chains; however, these changes do not appear to have a significant impact on frictional performance. Full article
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Open AccessArticle
Raman Study of Strain Relaxation from Grain Boundaries in Epitaxial Graphene Grown by Chemical Vapor Deposition on SiC
Nanomaterials 2019, 9(3), 372; https://doi.org/10.3390/nano9030372 - 05 Mar 2019
Cited by 1
Abstract
Strains in graphene play a significant role in graphene-based electronics, but many aspects of the grain boundary effects on strained graphene remain unclear. Here, the relationship between grain boundary and strain property of graphene grown by chemical vapor deposition (CVD) on the C-face [...] Read more.
Strains in graphene play a significant role in graphene-based electronics, but many aspects of the grain boundary effects on strained graphene remain unclear. Here, the relationship between grain boundary and strain property of graphene grown by chemical vapor deposition (CVD) on the C-face of SiC substrate has been investigated by Raman spectroscopy. It is shown that abundant boundary-like defects exist in the graphene film and the blue-shifted 2D-band frequency, which results from compressive strain in graphene film, shifts downward linearly as 1/La increases. Strain relaxation caused by grain boundary diffusion is considered to be the reason and the mechanism is analyzed in detail. Full article
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Open AccessArticle
Tunable Electronic Properties of Nitrogen and Sulfur Doped Graphene: Density Functional Theory Approach
Nanomaterials 2019, 9(2), 268; https://doi.org/10.3390/nano9020268 - 15 Feb 2019
Cited by 7
Abstract
We calculated the band structures of a variety of N- and S-doped graphenes in order to understand the effects of the N and S dopants on the graphene electronic structure using density functional theory (DFT). Band-structure analysis revealed energy band upshifting above the [...] Read more.
We calculated the band structures of a variety of N- and S-doped graphenes in order to understand the effects of the N and S dopants on the graphene electronic structure using density functional theory (DFT). Band-structure analysis revealed energy band upshifting above the Fermi level compared to pristine graphene following doping with three nitrogen atoms around a mono-vacancy defect, which corresponds to p-type nature. On the other hand, the energy bands were increasingly shifted downward below the Fermi level with increasing numbers of S atoms in N/S-co-doped graphene, which results in n-type behavior. Hence, modulating the structure of graphene through N- and S-doping schemes results in the switching of “p-type” to “n-type” behavior with increasing S concentration. Mulliken population analysis indicates that the N atom doped near a mono-vacancy is negatively charged due to its higher electronegativity compared to C, whereas the S atom doped near a mono-vacancy is positively charged due to its similar electronegativity to C and its additional valence electrons. As a result, doping with N and S significantly influences the unique electronic properties of graphene. Due to their tunable band-structure properties, the resulting N- and S-doped graphenes can be used in energy and electronic-device applications. In conclusion, we expect that doping with N and S will lead to new pathways for tailoring and enhancing the electronic properties of graphene at the atomic level. Full article
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Open AccessArticle
Drain Current Model for Double Gate Tunnel-FETs with InAs/Si Heterojunction and Source-Pocket Architecture
Nanomaterials 2019, 9(2), 181; https://doi.org/10.3390/nano9020181 - 01 Feb 2019
Cited by 3
Abstract
The practical use of tunnel field-effect transistors is retarded by the low on-state current. In this paper, the energy-band engineering of InAs/Si heterojunction and novel device structure of source-pocket concept are combined in a single tunnel field-effect transistor to extensively boost the device [...] Read more.
The practical use of tunnel field-effect transistors is retarded by the low on-state current. In this paper, the energy-band engineering of InAs/Si heterojunction and novel device structure of source-pocket concept are combined in a single tunnel field-effect transistor to extensively boost the device performance. The proposed device shows improved tunnel on-state current and subthreshold swing. In addition, analytical potential model for the proposed device is developed and tunneling current is also calculated. Good agreement of the modeled results with numerical simulations verifies the validation of our model. With significantly reduced simulation time while acceptable accuracy, the model would be helpful for the further investigation of TFET-based circuit simulations. Full article
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Open AccessArticle
Tin, The Enabler—Hydrogen Diffusion into Ruthenium
Nanomaterials 2019, 9(1), 129; https://doi.org/10.3390/nano9010129 - 21 Jan 2019
Cited by 4
Abstract
Hydrogen interaction with ruthenium is of particular importance for the ruthenium-capped multilayer reflectors used in extreme ultraviolet (EUV) lithography. Hydrogen causes blistering, which leads to a loss of reflectivity. This problem is aggravated by tin. This study aims to uncover the mechanism via [...] Read more.
Hydrogen interaction with ruthenium is of particular importance for the ruthenium-capped multilayer reflectors used in extreme ultraviolet (EUV) lithography. Hydrogen causes blistering, which leads to a loss of reflectivity. This problem is aggravated by tin. This study aims to uncover the mechanism via which tin affects the hydrogen uptake, with a view to mitigation. We report here the results of a study of hydrogen interaction with the ruthenium surface in the presence of tin using Density Functional Theory and charge density analyses. Our calculations show a significant drop in the energy barrier to hydrogen penetration when a tin atom or a tin hydride molecule (SnHx) is adsorbed on the ruthenium surface; the barrier has been found to drop in all tested cases with tin, from 1.06 eV to as low as 0.28 eV in the case of stannane (SnH4). Analyses show that, due to charge transfer from the less electronegative tin to hydrogen and ruthenium, charge accumulates around the diffusing hydrogen atom and near the ruthenium surface atoms. The reduced atomic volume of hydrogen, together with the effect of electron–electron repulsion from the ruthenium surface charge, facilitates subsurface penetration. Understanding the nature of tin’s influence on hydrogen penetration will guide efforts to mitigate blistering damage of EUV optics. It also holds great interest for applications where hydrogen penetration is desirable, such as hydrogen storage. Full article
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Open AccessArticle
Quantum-Mechanical Study of Nanocomposites with Low and Ultra-Low Interface Energies
Nanomaterials 2018, 8(12), 1057; https://doi.org/10.3390/nano8121057 - 15 Dec 2018
Cited by 5
Abstract
We applied first-principles electronic structure calculations to study structural, thermodynamic and elastic properties of nanocomposites exhibiting nearly perfect match of constituting phases. In particular, two combinations of transition-metal disilicides and one pair of magnetic phases containing the Fe and Al atoms with different [...] Read more.
We applied first-principles electronic structure calculations to study structural, thermodynamic and elastic properties of nanocomposites exhibiting nearly perfect match of constituting phases. In particular, two combinations of transition-metal disilicides and one pair of magnetic phases containing the Fe and Al atoms with different atomic ordering were considered. Regarding the disilicides, nanocomposites MoSi 2 /WSi 2 with constituents crystallizing in the tetragonal C11 b structure and TaSi 2 /NbSi 2 with individual phases crystallizing in the hexagonal C40 structure were simulated. Constituents within each pair of materials exhibit very similar structural and elastic properties and for their nanocomposites we obtained ultra-low (nearly zero) interface energy (within the error bar of our calculations, i.e., about 0.005 J/m 2 ). The interface energy was found to be nearly independent on the width of individual constituents within the nanocomposites and/or crystallographic orientation of the interfaces. As far as the nanocomposites containing Fe and Al were concerned, we simulated coherent superlattices formed by an ordered Fe 3 Al intermetallic compound and a disordered Fe-Al phase with 18.75 at.% Al, the α -phase. Both phases were structurally and elastically quite similar but the disordered α -phase lacked a long-range periodicity. To determine the interface energy in these nanocomposites, we simulated seven different distributions of atoms in the α -phase interfacing the Fe 3 Al intermetallic compound. The resulting interface energies ranged from ultra low to low values, i.e., from 0.005 to 0.139 J/m 2 . The impact of atomic distribution on the elastic properties was found insignificant but local magnetic moments of the iron atoms depend sensitively on the type and distribution of surrounding atoms. Full article
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