http://scholar.google.com/citations?hl=en&user=95SvbM8AAAAJ
61.
M, Ajayan Pulickel; Woellner, Cristiano F; Owuor, Peter S; Trigueiro, Joao P C; Machado, Leonardo D; Silva, Wellington M; Kosolwattana, Suppanat; Jaques, Ygor M; Silva, Carlos J R; Pedrotti, Jairo; Tiwary, Chandra S; Chipara, Alin C; Galvao, Douglas; Chopra, Nitin; Odeh, Ihab N; Silva, Glaura G.
Hybrid 2D Nanostructures for Mechanical Reinforcement and Thermal Conductivity Enhancement in Polymer Composite Journal Article
Em: Composites Science and Technology, vol. 159, não 5, pp. 103-110, 2018.
@article{M2018,
title = {Hybrid 2D Nanostructures for Mechanical Reinforcement and Thermal Conductivity Enhancement in Polymer Composite},
author = {Ajayan Pulickel M and Cristiano F Woellner and Peter S Owuor and Joao P C Trigueiro and Leonardo D Machado and Wellington M Silva and Suppanat Kosolwattana and Ygor M Jaques and Carlos J R Silva and Jairo Pedrotti and Chandra S Tiwary and Alin C Chipara and Douglas Galvao and Nitin Chopra and Ihab N Odeh and Glaura G. Silva
},
doi = {https://doi.org/10.1016/j.compscitech.2018.01.032},
year = {2018},
date = {2018-01-01},
journal = {Composites Science and Technology},
volume = {159},
number = {5},
pages = {103-110},
abstract = {Hexagonal boron nitride (h-BN), graphene oxide (GO) and hybrid (GO/h-BN) nanosheets were employed as fillers in order to enhance the physical properties of the polymer matrix. Composites based in epoxy and these two-dimensional (2D) nanofillers were produced with different wt% and their microstructure, mechanical and thermal properties were investigated. Increases up to 140% in tensile strength, 177% in ultimate strain and 32% in elastic modulus were observed for the hybrid GO/h-BN composite with 0.5 wt% content. The hybrid nanofiller also contributed to the increase up to 142% on thermal conductivity with respect to the pure epoxy for GO/h-BN composite with 2.0 wt% content. Molecular dynamic simulation was used to predict the behavior of possible stacking arrangements between h-BN and GO nanosheets tensioned by normal and shear forces. The results showed that the hybrid GO/h-BN combination can prevent the re-stacking process of exfoliated layers, demonstrating the synergism between these nanostructures with the final effect of better dispersion in the composite material. The excellent thermal and mechanical performance of these hybrid composites en- gineered by the combination of different types of the 2D inorganic nanoparticles make them multifunctional candidates for advanced materials applications.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Hexagonal boron nitride (h-BN), graphene oxide (GO) and hybrid (GO/h-BN) nanosheets were employed as fillers in order to enhance the physical properties of the polymer matrix. Composites based in epoxy and these two-dimensional (2D) nanofillers were produced with different wt% and their microstructure, mechanical and thermal properties were investigated. Increases up to 140% in tensile strength, 177% in ultimate strain and 32% in elastic modulus were observed for the hybrid GO/h-BN composite with 0.5 wt% content. The hybrid nanofiller also contributed to the increase up to 142% on thermal conductivity with respect to the pure epoxy for GO/h-BN composite with 2.0 wt% content. Molecular dynamic simulation was used to predict the behavior of possible stacking arrangements between h-BN and GO nanosheets tensioned by normal and shear forces. The results showed that the hybrid GO/h-BN combination can prevent the re-stacking process of exfoliated layers, demonstrating the synergism between these nanostructures with the final effect of better dispersion in the composite material. The excellent thermal and mechanical performance of these hybrid composites en- gineered by the combination of different types of the 2D inorganic nanoparticles make them multifunctional candidates for advanced materials applications.
62.
Oliveira, Eliezer Fernando; da Silva Autreto, Pedro Alves; Galvao, Douglas Soares
Silver Hardening via Hypersonic Impacts Journal Article
Em: MRS Advances, vol. 3, não 8-9, pp. 489-494, 2018.
@article{Oliveira2018b,
title = {Silver Hardening via Hypersonic Impacts},
author = {Eliezer Fernando Oliveira and Pedro Alves da Silva Autreto and Douglas Soares Galvao},
url = {https://www.cambridge.org/core/journals/mrs-advances/article/silver-hardening-via-hypersonic-impacts/6A35FAB117B4FD244BBD11A64CD25160},
doi = {DOI: 10.1557/adv.2018. 173},
year = {2018},
date = {2018-01-01},
journal = {MRS Advances},
volume = {3},
number = {8-9},
pages = {489-494},
abstract = {The search for new ultra strong materials has been a very active research area. With relation to metals, a successful way to improve their strength is by the creation of a gradient of nanograins (GNG) inside the material. Recently, R. Thevamaran et al. [Science v354, 312- 316 (2016)] propose a single step method based on high velocity impact of silver nanocubes to produce high-quality GNG. This method consists of producing high impact collisions of silver cubes at hypersonic velocity (~400 m/s) against a rigid wall. Although they observed an improvement in the mechanical properties of the silver after the impact, the GNG creation and the strengthening mechanism at nanoscale remain unclear. In order to gain further insights about these mechanisms, we carried out fully atomistic molecular dynamics simulations (MD) to investigate the atomic conformations/rearrangements during and after high impact collisions of silver nanocubes at ultrasonic velocity. Our results indicate the co- existence of polycrystalline arrangements after the impact formed by core HCP domains surrounded by FCC ones, which could also contribute to explain the structural hardening.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The search for new ultra strong materials has been a very active research area. With relation to metals, a successful way to improve their strength is by the creation of a gradient of nanograins (GNG) inside the material. Recently, R. Thevamaran et al. [Science v354, 312- 316 (2016)] propose a single step method based on high velocity impact of silver nanocubes to produce high-quality GNG. This method consists of producing high impact collisions of silver cubes at hypersonic velocity (~400 m/s) against a rigid wall. Although they observed an improvement in the mechanical properties of the silver after the impact, the GNG creation and the strengthening mechanism at nanoscale remain unclear. In order to gain further insights about these mechanisms, we carried out fully atomistic molecular dynamics simulations (MD) to investigate the atomic conformations/rearrangements during and after high impact collisions of silver nanocubes at ultrasonic velocity. Our results indicate the co- existence of polycrystalline arrangements after the impact formed by core HCP domains surrounded by FCC ones, which could also contribute to explain the structural hardening.
63.
Oliveira, Eliezer Fernando; Paupitz, Ricardo; da Silva Autreto, Pedro Alves; Moshkalev, Stanislav; Galvao, Douglas Soares
Improving Graphene-metal Contacts: Thermal Induced Polishing Journal Article
Em: MRS Advances, vol. 3, não 1-2, pp. 73-78, 2018.
@article{Oliveira2018c,
title = {Improving Graphene-metal Contacts: Thermal Induced Polishing },
author = {Eliezer Fernando Oliveira and Ricardo Paupitz and Pedro Alves da Silva Autreto and Stanislav Moshkalev and Douglas Soares Galvao},
url = {https://www.cambridge.org/core/journals/mrs-advances/article/improving-graphenemetal-contacts-thermal-induced-polishing/AC01C4996B90B0EE5E03220604071D12},
doi = {https://doi.org/10.1557/adv.2018.66},
year = {2018},
date = {2018-01-01},
journal = {MRS Advances},
volume = {3},
number = {1-2},
pages = {73-78},
abstract = {Graphene is a very promising material for nanoelectronics applications due to its unique and remarkable electronic and thermal properties. However, when deposited on metallic electrodes the overall thermal conductivity is significantly decreased. This phenomenon has been attributed to the mismatch between the interfaces and contact thermal resistance. Experimentally, one way to improve the graphene/metal contact is thorough high-temperature annealing, but the detailed mechanisms behind these processes remain unclear. In order to address these questions, we carried out fully atomistic reactive molecular dynamics simulations using the ReaxFF force field to investigate the interactions between multi-layer graphene and metallic electrodes (nickel) under (thermal) annealing. Our results show that the annealing induces an upward-downward movement of the graphene layers, causing a pile-driver-like effect over the metallic surface. This graphene induced movements cause a planarization (thermal polishing-like effect) of the metallic surface, which results in the increase of the effective graphene/metal contact area. This can also explain the experimentally observed improvements of the thermal and electric conductivities.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Graphene is a very promising material for nanoelectronics applications due to its unique and remarkable electronic and thermal properties. However, when deposited on metallic electrodes the overall thermal conductivity is significantly decreased. This phenomenon has been attributed to the mismatch between the interfaces and contact thermal resistance. Experimentally, one way to improve the graphene/metal contact is thorough high-temperature annealing, but the detailed mechanisms behind these processes remain unclear. In order to address these questions, we carried out fully atomistic reactive molecular dynamics simulations using the ReaxFF force field to investigate the interactions between multi-layer graphene and metallic electrodes (nickel) under (thermal) annealing. Our results show that the annealing induces an upward-downward movement of the graphene layers, causing a pile-driver-like effect over the metallic surface. This graphene induced movements cause a planarization (thermal polishing-like effect) of the metallic surface, which results in the increase of the effective graphene/metal contact area. This can also explain the experimentally observed improvements of the thermal and electric conductivities.
64.
Leonardo D Machado Cristiano F Woellner, Pedro AS Autreto; Galvao, Douglas S
Structural Transformations of Carbon and Boron Nitride Nanoscrolls at High Impact Collisions Online
2017, (preprint ArXiv:1711.00378).
@online{Woellner2017,
title = {Structural Transformations of Carbon and Boron Nitride Nanoscrolls at High Impact Collisions},
author = {Cristiano F Woellner, Leonardo D Machado, Pedro AS Autreto, Jose M de Sousa, and Douglas S Galvao},
url = {https://arxiv.org/pdf/1711.00378.pdf},
year = {2017},
date = {2017-11-01},
abstract = {The behavior of nanostructures under high strain-rate conditions has been object of theoretical and experimental investigations in recent years. For instance, it has been shown that carbon and boron nitride nanotubes can be unzipped into nanoribbons at high velocity impacts. However, the response of many nanostructures to high strain-rate conditions is still not completely understood. In this work we have investigated through fully atomistic reactive (ReaxFF) molecular dynamics (MD) simulations the mechanical behavior of carbon (CNS) and boron nitride nanoscrolls (BNS) colliding against solid targets at high velocities,. CNS (BNS) nanoscrolls are graphene (boron nitride) membranes rolled up into papyrus-like
structures. Their open-ended topology leads to unique properties not found in close-ended analogues, such as nanotubes.Our results show that the collision products are mainly determined by impact velocities and by two impact angles, which
define the position of the scroll (i) axis and (ii) open edge relative to the target. Our MD results showed that for appropriate velocities and orientations large-scale deformations and nanoscroll fracture can occur. We also observed unscrolling (scrolls going back to quasi-planar membranes), scroll unzipping into nanoribbons, and significant
reconstruction due to breaking and/or formation of new chemical bonds. For particular edge orientations and velocities, conversion from open to close-ended topology is also possible, due to the fusion of nanoscroll walls.},
note = {preprint ArXiv:1711.00378},
keywords = {},
pubstate = {published},
tppubtype = {online}
}
The behavior of nanostructures under high strain-rate conditions has been object of theoretical and experimental investigations in recent years. For instance, it has been shown that carbon and boron nitride nanotubes can be unzipped into nanoribbons at high velocity impacts. However, the response of many nanostructures to high strain-rate conditions is still not completely understood. In this work we have investigated through fully atomistic reactive (ReaxFF) molecular dynamics (MD) simulations the mechanical behavior of carbon (CNS) and boron nitride nanoscrolls (BNS) colliding against solid targets at high velocities,. CNS (BNS) nanoscrolls are graphene (boron nitride) membranes rolled up into papyrus-like
structures. Their open-ended topology leads to unique properties not found in close-ended analogues, such as nanotubes.Our results show that the collision products are mainly determined by impact velocities and by two impact angles, which
define the position of the scroll (i) axis and (ii) open edge relative to the target. Our MD results showed that for appropriate velocities and orientations large-scale deformations and nanoscroll fracture can occur. We also observed unscrolling (scrolls going back to quasi-planar membranes), scroll unzipping into nanoribbons, and significant
reconstruction due to breaking and/or formation of new chemical bonds. For particular edge orientations and velocities, conversion from open to close-ended topology is also possible, due to the fusion of nanoscroll walls.
structures. Their open-ended topology leads to unique properties not found in close-ended analogues, such as nanotubes.Our results show that the collision products are mainly determined by impact velocities and by two impact angles, which
define the position of the scroll (i) axis and (ii) open edge relative to the target. Our MD results showed that for appropriate velocities and orientations large-scale deformations and nanoscroll fracture can occur. We also observed unscrolling (scrolls going back to quasi-planar membranes), scroll unzipping into nanoribbons, and significant
reconstruction due to breaking and/or formation of new chemical bonds. For particular edge orientations and velocities, conversion from open to close-ended topology is also possible, due to the fusion of nanoscroll walls.
65.
Parambath M Sudeep Sruthi Radhakrishnan, Jun Hyoung Park; Ajayan, Pulickel M
Multifunctional Hybrids Based on 2D Fluorinated Graphene Oxide and Superparamagnetic Iron Oxide Nanoparticles Journal Article
Em: Particle & Particle Systems Characterization, vol. 34, não 11, pp. 1700245, 2017.
@article{Radhakrishnan2017,
title = {Multifunctional Hybrids Based on 2D Fluorinated Graphene Oxide and Superparamagnetic Iron Oxide Nanoparticles},
author = {Sruthi Radhakrishnan, Parambath M Sudeep, Jun Hyoung Park, Cristiano F Woellner, Kierstein Maladonado, Douglas S Galvao, Benny Abraham Kaipparettu, Chandra Sekhar Tiwary, and Pulickel M Ajayan},
url = {http://onlinelibrary.wiley.com/doi/10.1002/ppsc.201700245/full},
doi = {DOI: 10.1002/ppsc.201700245},
year = {2017},
date = {2017-11-01},
journal = {Particle & Particle Systems Characterization},
volume = {34},
number = {11},
pages = {1700245},
abstract = {Carbon-based nanomaterials have garnered a lot of attention in the research of yesteryear. Here this study reports a composite based on fluorinated graphene oxide—a multifunctional subsidiary of graphene; and iron oxide nanoparticles as a contrast agent for magnetic resonance imaging (MRI). Extensive structural and functional characterization is carried out to understand composite behavior toward biotoxicity and its performance as a contrast agent. The electron withdrawing fluorine group decreases the charge transfer to iron oxide increasing the magnetic saturation of the composite thus enhancing the contrast. The interaction of paramagnetic and superparamagnetic systems yields a superior contrast agent for MRI and fluorescent imaging.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Carbon-based nanomaterials have garnered a lot of attention in the research of yesteryear. Here this study reports a composite based on fluorinated graphene oxide—a multifunctional subsidiary of graphene; and iron oxide nanoparticles as a contrast agent for magnetic resonance imaging (MRI). Extensive structural and functional characterization is carried out to understand composite behavior toward biotoxicity and its performance as a contrast agent. The electron withdrawing fluorine group decreases the charge transfer to iron oxide increasing the magnetic saturation of the composite thus enhancing the contrast. The interaction of paramagnetic and superparamagnetic systems yields a superior contrast agent for MRI and fluorescent imaging.
66.
Han, Yang; Zhou, Yanguang; Qin, Guangzhao; Dong, Jinming; Galvao, Douglas S; Hu, Ming
Unprecedented mechanical response of the lattice thermal conductivity of auxetic carbon crystals Journal Article
Em: Carbon, vol. 122, pp. 374-380, 2017.
@article{Han2017,
title = {Unprecedented mechanical response of the lattice thermal conductivity of auxetic carbon crystals},
author = {Han, Yang and Zhou, Yanguang and Qin, Guangzhao and Dong, Jinming and Galvao, Douglas S and Hu, Ming},
url = {http://www.sciencedirect.com/science/article/pii/S0008622317306760},
doi = {10.1016/j.carbon.2017.06.100},
year = {2017},
date = {2017-10-01},
journal = {Carbon},
volume = {122},
pages = {374-380},
abstract = {Lattice thermal conductivity (κ) of bulk materials usually increases under compression and decreases under tension, while there are still some unusual systems, exhibiting reduced κ when compressed. However, to date it has never been reported for a bulk material, whose κ is substantially enhanced under tensile strain. In this paper, we have studied thermal transport of three auxetic carbon crystals: cis-C, trans-C and hin-C for short, and their strain responses by performing first-principles calculations. It is intriguing to find that their κ are much lower than those of their allotropes, and further decrease abnormally under compression. More strikingly, κ of trans-C (cis-C) anomalously increases with tensile strain up to 7% (6%) with maximum κ of almost 7 (5) times larger than the unstrained value. The abnormal strain dependent κ are attributed to the dominant role of the enhancement of phonon lifetime under stretching, which can be further explained from the unique atomic structure of the main chain of polydiacetylene in trans-C and cis-C. The weakening of phonon anharmonicity is reflected by the enhancement of root mean-square displacement values. The reported giant augmentation of κ may inspire intensive research on auxetic carbon crystals as potential materials for emerging nanoelectronic devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Lattice thermal conductivity (κ) of bulk materials usually increases under compression and decreases under tension, while there are still some unusual systems, exhibiting reduced κ when compressed. However, to date it has never been reported for a bulk material, whose κ is substantially enhanced under tensile strain. In this paper, we have studied thermal transport of three auxetic carbon crystals: cis-C, trans-C and hin-C for short, and their strain responses by performing first-principles calculations. It is intriguing to find that their κ are much lower than those of their allotropes, and further decrease abnormally under compression. More strikingly, κ of trans-C (cis-C) anomalously increases with tensile strain up to 7% (6%) with maximum κ of almost 7 (5) times larger than the unstrained value. The abnormal strain dependent κ are attributed to the dominant role of the enhancement of phonon lifetime under stretching, which can be further explained from the unique atomic structure of the main chain of polydiacetylene in trans-C and cis-C. The weakening of phonon anharmonicity is reflected by the enhancement of root mean-square displacement values. The reported giant augmentation of κ may inspire intensive research on auxetic carbon crystals as potential materials for emerging nanoelectronic devices.
67.
BORGES, Daiane DAMASCENO; NORMAND, Perine; PERMIAKOVA, Anastasia; BABARAO, Ravichandar; HEYMANS, Nicolas; GALVAO, Douglas S.; SERRE, Christian; WEIRELD, Guy DE; MAURIN, Guillaume
Gas Adsorption and Separation by the Al-based Metal-Organic Framework MIL-160 Journal Article
Em: Journal of Physical Chemistry C, vol. 121, não 48, pp. 26822–26832, 2017.
@article{BORGES2017b,
title = {Gas Adsorption and Separation by the Al-based Metal-Organic Framework MIL-160},
author = {Daiane DAMASCENO BORGES and Perine NORMAND and Anastasia PERMIAKOVA and Ravichandar BABARAO and Nicolas HEYMANS and Douglas S. GALVAO and Christian SERRE and Guy DE WEIRELD and Guillaume MAURIN},
url = {http://pubs.acs.org/doi/abs/10.1021/acs.jpcc.7b08856},
doi = {DOI: 10.1021/acs.jpcc.7b08856},
year = {2017},
date = {2017-09-14},
journal = {Journal of Physical Chemistry C},
volume = {121},
number = {48},
pages = {26822–26832},
abstract = {One of the most promising technologies, with a low energy penalty, for CO2 capture from diverse gas mixtures is based on the adsorption process using adsorbents. Many efforts are still currently deployed to search for water stable porous metal–organic frameworks (MOFs) with high CO2 affinity combined with large CO2 uptake. In this context, we have selected the water stable and easily scalable Al-based MOF MIL-160 showing an ultramicroporosity and potential interacting sites (hydroxyl and furan), both features being a priori relevant to favor the selective adsorption of CO2 over other gases including H2, N2, CH4, and CO. Density functional theory (DFT) and force-field-based grand-canonical Monte Carlo (GCMC) simulations were first coupled to predict the strength of host/guest interactions and the adsorption isotherms for all guests as single components and binary mixtures. This computational approach reveals the promises of this solid for the selective adsorption of CO2 with respect to these other investigated gases, controlled by a combination of thermodynamics and confinement effects. These predicted performances were further supported by real-coadsorption measurements performed on shaped samples which indicated that MIL-160(Al) shows promising performance for the selective CO2 capture in post- and pre-combustion conditions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
One of the most promising technologies, with a low energy penalty, for CO2 capture from diverse gas mixtures is based on the adsorption process using adsorbents. Many efforts are still currently deployed to search for water stable porous metal–organic frameworks (MOFs) with high CO2 affinity combined with large CO2 uptake. In this context, we have selected the water stable and easily scalable Al-based MOF MIL-160 showing an ultramicroporosity and potential interacting sites (hydroxyl and furan), both features being a priori relevant to favor the selective adsorption of CO2 over other gases including H2, N2, CH4, and CO. Density functional theory (DFT) and force-field-based grand-canonical Monte Carlo (GCMC) simulations were first coupled to predict the strength of host/guest interactions and the adsorption isotherms for all guests as single components and binary mixtures. This computational approach reveals the promises of this solid for the selective adsorption of CO2 with respect to these other investigated gases, controlled by a combination of thermodynamics and confinement effects. These predicted performances were further supported by real-coadsorption measurements performed on shaped samples which indicated that MIL-160(Al) shows promising performance for the selective CO2 capture in post- and pre-combustion conditions.
68.
Sajadi, Seyed Mohammad; Owuor, Peter Samora; Schara, Steven; Woellner, Cristiano F.; Rodrigues, Varlei; Vajtai, Robert; Lou, Jun; Galvao, Douglas S.; Tiwary, Chandra Sekhar; Ajayan, Pulickel M.
Multi-scale Geometric Design Principles Applied to 3D Printed Schwartizes Journal Article
Em: Advanced Materials, vol. 2017, pp. 1704820, 2017.
@article{Sajadi2017,
title = {Multi-scale Geometric Design Principles Applied to 3D Printed Schwartizes},
author = {Seyed Mohammad Sajadi and Peter Samora Owuor and Steven Schara and Cristiano F. Woellner and Varlei Rodrigues and Robert Vajtai and Jun Lou and Douglas S. Galvao and Chandra Sekhar Tiwary and Pulickel M. Ajayan},
url = {http://onlinelibrary.wiley.com/doi/10.1002/adma.201704820/full},
doi = {10.1002/adma.201704820},
year = {2017},
date = {2017-09-14},
journal = {Advanced Materials},
volume = {2017},
pages = {1704820},
abstract = {Schwartzites are 3D porous solids with periodic minimal surfaces having negative Gaussian curvatures and can possess unusual mechanical and electronic properties. The mechanical behavior of primitive and gyroid schwartzite structures across different length scales is investigated after these geometries are 3D printed at centimeter length scales based on molec- ular models. Molecular dynamics and nite elements simulations are used
to gain further understanding on responses of these complex solids under compressive loads and kinetic impact experiments. The results show that these structures hold great promise as high load bearing and impact-resistant materials due to a unique layered deformation mechanism that emerges in these architectures during loading. Easily scalable techniques such as 3D printing can be used for exploring mechanical behavior of various predicted complex geometrical shapes to build innovative engineered materials with tunable properties.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Schwartzites are 3D porous solids with periodic minimal surfaces having negative Gaussian curvatures and can possess unusual mechanical and electronic properties. The mechanical behavior of primitive and gyroid schwartzite structures across different length scales is investigated after these geometries are 3D printed at centimeter length scales based on molec- ular models. Molecular dynamics and nite elements simulations are used
to gain further understanding on responses of these complex solids under compressive loads and kinetic impact experiments. The results show that these structures hold great promise as high load bearing and impact-resistant materials due to a unique layered deformation mechanism that emerges in these architectures during loading. Easily scalable techniques such as 3D printing can be used for exploring mechanical behavior of various predicted complex geometrical shapes to build innovative engineered materials with tunable properties.
to gain further understanding on responses of these complex solids under compressive loads and kinetic impact experiments. The results show that these structures hold great promise as high load bearing and impact-resistant materials due to a unique layered deformation mechanism that emerges in these architectures during loading. Easily scalable techniques such as 3D printing can be used for exploring mechanical behavior of various predicted complex geometrical shapes to build innovative engineered materials with tunable properties.
69.
Manimunda, P; Nakanishi, Y; Jaques, YM; Susarla, S; Woellner, CF; Bhowmick, S; Asif, SAS; Galvao, DS; Tiwary, CS; Ajayan, PM
Nanoscale deformation and friction characteristics of atomically thin WSe2 and heterostructure using nanoscratch and Raman spectroscopy Journal Article
Em: 2D Materials, vol. 4, não 4, pp. 045005, 2017.
@article{Manimunda2017,
title = {Nanoscale deformation and friction characteristics of atomically thin WSe2 and heterostructure using nanoscratch and Raman spectroscopy},
author = {Manimunda, P and Nakanishi, Y and Jaques, YM and Susarla, S and Woellner, CF and Bhowmick, S and Asif, SAS and Galvao, DS and Tiwary, CS and Ajayan, PM},
url = {http://iopscience.iop.org/article/10.1088/2053-1583/aa8475/meta},
doi = {10.1088/2053-1583/aa8475},
year = {2017},
date = {2017-08-23},
journal = {2D Materials},
volume = {4},
number = {4},
pages = {045005},
abstract = {2D transition metals di-selenides are attracting a lot of attention due to their interesting optical, chemical and electronics properties. Here, the deformation characteristics of monolayer, multi- layer WSe2 and its heterostructure with MoSe2 were investigated using a new technique that combines nanoscratch and Raman spectroscopy. The 2D monolayer WSe2 showed anisotropy in deformation. Effect of number of WSe2 layers on friction characteristics were explored in detail. Experimental observations were further supported by MD simulations. Raman spectra recorded from the scratched regions showed strain induced degeneracy splitting. Further nano-scale scratch tests were extended to MoSe2–WSe2 lateral heterostructures. Effect of deformation on lateral hetero junctions were further analysed using PL and Raman spectroscopy. This new technique is completely general and can be applied to study other 2D materials.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2D transition metals di-selenides are attracting a lot of attention due to their interesting optical, chemical and electronics properties. Here, the deformation characteristics of monolayer, multi- layer WSe2 and its heterostructure with MoSe2 were investigated using a new technique that combines nanoscratch and Raman spectroscopy. The 2D monolayer WSe2 showed anisotropy in deformation. Effect of number of WSe2 layers on friction characteristics were explored in detail. Experimental observations were further supported by MD simulations. Raman spectra recorded from the scratched regions showed strain induced degeneracy splitting. Further nano-scale scratch tests were extended to MoSe2–WSe2 lateral heterostructures. Effect of deformation on lateral hetero junctions were further analysed using PL and Raman spectroscopy. This new technique is completely general and can be applied to study other 2D materials.
70.
Owuor, Peter Samora; Park, Ok-Kyung; Woellner, Cristiano F; Jalilov, Almaz S; Susarla, Sandhya; Joyner, Jarin; Ozden, Sehmus; Duy, LuongXuan; Villegas Salvatierra, Rodrigo; Vajtai, Robert; Tour, James M; Lou, Jun; Galvao, Douglas S; Tiwary, Chandra S; Ajayan, P M
Lightweight Hexagonal Boron Nitride Foam for CO2 Absorption Journal Article
Em: ACS Nano, vol. 11, não 8, pp. 8944–8952, 2017.
@article{Owuor2017b,
title = {Lightweight Hexagonal Boron Nitride Foam for CO2 Absorption},
author = {Owuor, Peter Samora and Park, Ok-Kyung and Woellner, Cristiano F and Jalilov, Almaz S and Susarla, Sandhya and Joyner, Jarin and Ozden, Sehmus and Duy, LuongXuan and Villegas Salvatierra, Rodrigo and Vajtai, Robert and Tour, James M and Lou, Jun and Galvao, Douglas S and Tiwary, Chandra S and Ajayan, P M},
url = {http://pubs.acs.org/doi/abs/10.1021/acsnano.7b03291},
doi = {10.1021/acsnano.7b03291},
year = {2017},
date = {2017-08-03},
journal = {ACS Nano},
volume = {11},
number = {8},
pages = {8944–8952},
abstract = {Weak van der Waals forces between inert hexagonal boron nitride (h-BN) nanosheets make it easy for them to slide over each other, resulting in an unstable structure in macroscopic dimensions. Creating interconnections between these inert nanosheets can remarkably enhance their mechanical properties. However, controlled design of such interconnections remains a fundamental problem for many applications of h-BN foams. In this work, a scalable in situ freeze-drying synthesis of low-density, lightweight 3D macroscopic structures made of h-BN nanosheets chemically connected by poly(vinyl alcohol) (PVA) molecules via chemical cross-link is demonstrated. Unlike pristine h-BN foam which disintegrates upon handling after freeze-drying, h-BN/PVA foams exhibit stable mechanical integrity in addition to high porosity and large surface area. Fully atomistic simulations are used to understand the interactions between h-BN nanosheets and PVA molecules. In addition, the h-BN/PVA foam is investigated as a possible CO2 absorption and as laser irradiation protection material.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Weak van der Waals forces between inert hexagonal boron nitride (h-BN) nanosheets make it easy for them to slide over each other, resulting in an unstable structure in macroscopic dimensions. Creating interconnections between these inert nanosheets can remarkably enhance their mechanical properties. However, controlled design of such interconnections remains a fundamental problem for many applications of h-BN foams. In this work, a scalable in situ freeze-drying synthesis of low-density, lightweight 3D macroscopic structures made of h-BN nanosheets chemically connected by poly(vinyl alcohol) (PVA) molecules via chemical cross-link is demonstrated. Unlike pristine h-BN foam which disintegrates upon handling after freeze-drying, h-BN/PVA foams exhibit stable mechanical integrity in addition to high porosity and large surface area. Fully atomistic simulations are used to understand the interactions between h-BN nanosheets and PVA molecules. In addition, the h-BN/PVA foam is investigated as a possible CO2 absorption and as laser irradiation protection material.
71.
Borges, Daiane Damasceno; Woellner, Cristiano F; Autreto, Pedro AS; Galvao, Douglas S
2017, (preprint arXiv:1702.00250).
@online{Borges2017b,
title = {Insights on the mechanism of water-alcohol separation in multilayer graphene oxide membranes: entropic versus enthalpic factors},
author = {Borges, Daiane Damasceno and Woellner, Cristiano F and Autreto, Pedro AS and Galvao, Douglas S},
url = {https://arxiv.org/abs/1706.06213},
year = {2017},
date = {2017-06-19},
abstract = {Experimental evidences have shown that graphene oxide (GO) can be impermeable to liquids, vapors and gases, while it allows a fast permeation of water molecules. The understanding of filtration mechanisms came mostly from studies dedicated to water desalination, while very few works have been dedicated to distilling alcohols. In this work, we have investigated the molecular level mechanism underlying the alcohol/water separation inside GO membranes. A series of molecular dynamics and Grand-Canonical Monte Carlo simulations were carried out to probe the ethanol/water and methanol/water separation through GO membranes composed of multiple layered graphene-based sheets with different interlayer distance values and number of oxygen-containing functional groups. Our results show that the size exclusion and membrane affinities are not sufficient to explain the selectivity. Besides that, the favorable water molecular arrangement inside GO 2D-channels forming a robust H-bond network and the fast water diffusion are crucial for an effective separation mechanism. In other words, the separation phenomenon is not only governed by affinities with the membrane (enthalpic mechanisms) but mainly by the geometry and size factors (entropic mechanisms). We verified that the 2D geometry channel with optimal interlayer distance are key factors for designing more efficient alcohol-water separation membranes. Our findings are consistent with the available experimental data and contribute to clarify important aspects of the separation behavior of confined alcohol/water in GO membranes.},
note = {preprint arXiv:1702.00250},
keywords = {},
pubstate = {published},
tppubtype = {online}
}
Experimental evidences have shown that graphene oxide (GO) can be impermeable to liquids, vapors and gases, while it allows a fast permeation of water molecules. The understanding of filtration mechanisms came mostly from studies dedicated to water desalination, while very few works have been dedicated to distilling alcohols. In this work, we have investigated the molecular level mechanism underlying the alcohol/water separation inside GO membranes. A series of molecular dynamics and Grand-Canonical Monte Carlo simulations were carried out to probe the ethanol/water and methanol/water separation through GO membranes composed of multiple layered graphene-based sheets with different interlayer distance values and number of oxygen-containing functional groups. Our results show that the size exclusion and membrane affinities are not sufficient to explain the selectivity. Besides that, the favorable water molecular arrangement inside GO 2D-channels forming a robust H-bond network and the fast water diffusion are crucial for an effective separation mechanism. In other words, the separation phenomenon is not only governed by affinities with the membrane (enthalpic mechanisms) but mainly by the geometry and size factors (entropic mechanisms). We verified that the 2D geometry channel with optimal interlayer distance are key factors for designing more efficient alcohol-water separation membranes. Our findings are consistent with the available experimental data and contribute to clarify important aspects of the separation behavior of confined alcohol/water in GO membranes.
72.
Miyazaki, Celina M; Maria, Marco AE; Borges, Daiane Damasceno; Woellner, Cristiano F; Brunetto, Gustavo; Fonseca, Alexandre F; Constantino, Carlos JL; Pereira-da-Silva, Marcelo A; de Siervo, Abner; Galvao, Douglas S; Riul Jr., Antonio
2017, (preprint arXiv:1702.00250).
@online{Miyazaki2017,
title = {Synthesis, characterization and computational simulation of graphene nanoplatelets stabilized in poly (styrene sulfonate) sodium salt},
author = {Miyazaki, Celina M and Maria, Marco AE and Borges, Daiane Damasceno and Woellner, Cristiano F and Brunetto, Gustavo and Fonseca, Alexandre F and Constantino, Carlos JL and Pereira-da-Silva, Marcelo A and de Siervo, Abner and Galvao, Douglas S and Riul Jr., Antonio},
url = {https://arxiv.org/abs/1705.10673},
year = {2017},
date = {2017-05-30},
abstract = {The production of large area interfaces and the use of scalable methods to build-up designed nanostructures generating advanced functional properties are of high interest for many materials science applications. Nevertheless, large area coverage remains a major problem for pristine graphene and here we present a hybrid, composite graphene-like material soluble in water, which can be exploited in many areas, such as energy storage, electrodes fabrication, selective membranes and biosensing. Graphene oxide (GO) was produced by the traditional Hummers method being further reduced in the presence of poly(styrene sulfonate) sodium salt (PSS), thus creating stable reduced graphene oxide (rGO) nanoplateles wrapped by PSS (GPSS). Molecular dynamics simulations were carried out of further clarify the interactions between PSS molecules and rGO nanoplatelets, with calculations supported by FTIR analysis. The intermolecular forces between rGO nanoplatelets and PSS lead to the formation of a hybrid material (GPSS) stabilized by van der Waals forces, allowing the fabrication of high quality layer-by-layer (LbL) films with polyalillamine hydrochloride (PAH). Raman and electrical characterizations corroborated the successful modifications in the electronic structures from GO to GPSS after the chemical treatment, resulting in (PAH/GPSS) LbL films four orders of magnitude more conductive than (PAH/GO).
},
note = {preprint arXiv:1702.00250},
keywords = {},
pubstate = {published},
tppubtype = {online}
}
The production of large area interfaces and the use of scalable methods to build-up designed nanostructures generating advanced functional properties are of high interest for many materials science applications. Nevertheless, large area coverage remains a major problem for pristine graphene and here we present a hybrid, composite graphene-like material soluble in water, which can be exploited in many areas, such as energy storage, electrodes fabrication, selective membranes and biosensing. Graphene oxide (GO) was produced by the traditional Hummers method being further reduced in the presence of poly(styrene sulfonate) sodium salt (PSS), thus creating stable reduced graphene oxide (rGO) nanoplateles wrapped by PSS (GPSS). Molecular dynamics simulations were carried out of further clarify the interactions between PSS molecules and rGO nanoplatelets, with calculations supported by FTIR analysis. The intermolecular forces between rGO nanoplatelets and PSS lead to the formation of a hybrid material (GPSS) stabilized by van der Waals forces, allowing the fabrication of high quality layer-by-layer (LbL) films with polyalillamine hydrochloride (PAH). Raman and electrical characterizations corroborated the successful modifications in the electronic structures from GO to GPSS after the chemical treatment, resulting in (PAH/GPSS) LbL films four orders of magnitude more conductive than (PAH/GO).
73.
Bizao, Rafael A; Botari, Tiago; Perim, Eric; Pugno, Nicola M; Galvao, Douglas S
Mechanical properties and fracture patterns of graphene (graphitic) nanowiggles Journal Article
Em: Carbon, vol. 119, pp. 431-437, 2017, (See also ArxIv version: https://arxiv.org/abs/1702.01100).
@article{Bizao2017b,
title = {Mechanical properties and fracture patterns of graphene (graphitic) nanowiggles},
author = {Bizao, Rafael A and Botari, Tiago and Perim, Eric and Pugno, Nicola M and Galvao, Douglas S},
url = {http://www.sciencedirect.com/science/article/pii/S0008622317303743},
doi = {10.1016/j.carbon.2017.04.018},
year = {2017},
date = {2017-04-14},
journal = {Carbon},
volume = {119},
pages = {431-437},
abstract = {Graphene nanowiggles (GNW) are graphene-based nanostructures obtained by making alternated regular cuts in pristine graphene nanoribbons. GNW were recently synthesized and it was demonstrated that they exhibit tunable electronic and magnetic properties by just varying their shape. Here, we have investigated the mechanical properties and fracture patterns of a large number of GNW of different shapes and sizes using fully atomistic reactive molecular dynamics simulations. Our results show that the GNW mechanical properties are strongly dependent on its shape and size and, as a general trend narrow sheets have larger ultimate strength and Young's modulus than wide ones. The estimated Young's modulus values were found to be in a range of ≈100−1000 GPa and the ultimate strength in a range of ≈20−110 GPa, depending on GNW shape. Also, super-ductile behavior under strain was observed for some structures.},
note = {See also ArxIv version: https://arxiv.org/abs/1702.01100},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Graphene nanowiggles (GNW) are graphene-based nanostructures obtained by making alternated regular cuts in pristine graphene nanoribbons. GNW were recently synthesized and it was demonstrated that they exhibit tunable electronic and magnetic properties by just varying their shape. Here, we have investigated the mechanical properties and fracture patterns of a large number of GNW of different shapes and sizes using fully atomistic reactive molecular dynamics simulations. Our results show that the GNW mechanical properties are strongly dependent on its shape and size and, as a general trend narrow sheets have larger ultimate strength and Young's modulus than wide ones. The estimated Young's modulus values were found to be in a range of ≈100−1000 GPa and the ultimate strength in a range of ≈20−110 GPa, depending on GNW shape. Also, super-ductile behavior under strain was observed for some structures.
74.
de Sousa, JM; Aguiar, AL; Girao, EC; Fonseca, Alexandre F; AG Filho, Souza; Galvao, Douglas S
Mechanical Properties and Fracture Patterns of Pentagraphene Membranes Online
2017, (preprint arXiv:1703.03789).
@online{deSousa2017,
title = {Mechanical Properties and Fracture Patterns of Pentagraphene Membranes},
author = {de Sousa, JM and Aguiar, AL and Girao, EC and Fonseca, Alexandre F and AG Filho, Souza and Galvao, Douglas S},
url = {https://arxiv.org/abs/1703.03789},
year = {2017},
date = {2017-03-10},
abstract = {Recently, a new two-dimensional carbon allotrope called pentagraphene (PG) was
proposed. PG exhibits mechanical and electronic interesting properties, including typical
band gap values of semiconducting materials. PG has a Cairo-tiling-like 2D lattice
of non coplanar pentagons and its mechanical properties have not been yet fully investigated.
In this work, we combined density functional theory (DFT) calculations and
reactive molecular dynamics (MD) simulations to investigate the mechanical properties
and fracture patterns of PG membranes under tensile strain. We show that PG
membranes can hold up to 20% of strain and that fracture occurs only after substantial
dynamical bond breaking and the formation of 7, 8 and 11 carbon rings and carbon
chains. The stress-strain behavior was observed to follow two regimes, one exhibiting linear elasticity followed by a plastic one, involving carbon atom re-hybridization with
the formation of carbon rings and chains. Our results also show that mechanically
induced structural transitions from PG to graphene is unlikely to occur, in contrast to
what was previously speculated in the literature.},
note = {preprint arXiv:1703.03789},
keywords = {},
pubstate = {published},
tppubtype = {online}
}
Recently, a new two-dimensional carbon allotrope called pentagraphene (PG) was
proposed. PG exhibits mechanical and electronic interesting properties, including typical
band gap values of semiconducting materials. PG has a Cairo-tiling-like 2D lattice
of non coplanar pentagons and its mechanical properties have not been yet fully investigated.
In this work, we combined density functional theory (DFT) calculations and
reactive molecular dynamics (MD) simulations to investigate the mechanical properties
and fracture patterns of PG membranes under tensile strain. We show that PG
membranes can hold up to 20% of strain and that fracture occurs only after substantial
dynamical bond breaking and the formation of 7, 8 and 11 carbon rings and carbon
chains. The stress-strain behavior was observed to follow two regimes, one exhibiting linear elasticity followed by a plastic one, involving carbon atom re-hybridization with
the formation of carbon rings and chains. Our results also show that mechanically
induced structural transitions from PG to graphene is unlikely to occur, in contrast to
what was previously speculated in the literature.
proposed. PG exhibits mechanical and electronic interesting properties, including typical
band gap values of semiconducting materials. PG has a Cairo-tiling-like 2D lattice
of non coplanar pentagons and its mechanical properties have not been yet fully investigated.
In this work, we combined density functional theory (DFT) calculations and
reactive molecular dynamics (MD) simulations to investigate the mechanical properties
and fracture patterns of PG membranes under tensile strain. We show that PG
membranes can hold up to 20% of strain and that fracture occurs only after substantial
dynamical bond breaking and the formation of 7, 8 and 11 carbon rings and carbon
chains. The stress-strain behavior was observed to follow two regimes, one exhibiting linear elasticity followed by a plastic one, involving carbon atom re-hybridization with
the formation of carbon rings and chains. Our results also show that mechanically
induced structural transitions from PG to graphene is unlikely to occur, in contrast to
what was previously speculated in the literature.
75.
Cristiano F Woellner Peter Samora Owuor, Tong Li
High Toughness in Ultralow Density Graphene Oxide Foam Journal Article
Em: Advanced Materials Interfaces, vol. 4, não 10, pp. 1700030, 2017.
@article{Owuor2017,
title = {High Toughness in Ultralow Density Graphene Oxide Foam},
author = {Peter Samora Owuor, Cristiano F Woellner, Tong Li, Soumya Vinod, Sehmus Ozden, Suppanat Kosolwattana, Sanjit Bhowmick, Luong Xuan Duy, Rodrigo V Salvatierra, Bingqing Wei, Syed AS Asif, James M Tour, Robert Vajtai, Jun Lou, Douglas S Galvão, Chandra Sekhar Tiwary, Pulickel Ajayan},
url = {http://onlinelibrary.wiley.com/doi/10.1002/admi.201700030/abstract },
doi = {10.1002/admi.201700030},
year = {2017},
date = {2017-03-01},
journal = {Advanced Materials Interfaces},
volume = {4},
number = {10},
pages = {1700030},
abstract = {Here, the scalable synthesis of low-density 3D macroscopic structure of graphene oxide (GO) interconnected with polydimethylsiloxane (PDMS) is reported. A controlled amount of PDMS is infused into the freeze-dried foam to result into a very rigid structure with improved mechanical properties, such as tensile plasticity and toughness. The PDMS wets the graphene oxide sheets and acts like glue between the 2D sheets. Molecular dynamics simulations are used to further elucidate the mechanisms of the interactions of graphene oxide layers with PDMS. The ability of using the interconnecting graphene oxide foam as an effective oil–water separator and stable insulating behavior to elevated temperatures are further demonstrated. The structural rigidity of the sample is also tested using laser impact and compared with GO foam.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Here, the scalable synthesis of low-density 3D macroscopic structure of graphene oxide (GO) interconnected with polydimethylsiloxane (PDMS) is reported. A controlled amount of PDMS is infused into the freeze-dried foam to result into a very rigid structure with improved mechanical properties, such as tensile plasticity and toughness. The PDMS wets the graphene oxide sheets and acts like glue between the 2D sheets. Molecular dynamics simulations are used to further elucidate the mechanisms of the interactions of graphene oxide layers with PDMS. The ability of using the interconnecting graphene oxide foam as an effective oil–water separator and stable insulating behavior to elevated temperatures are further demonstrated. The structural rigidity of the sample is also tested using laser impact and compared with GO foam.
76.
Splugues, Vinicius; da Silva Autreto, Pedro Alves; Galvao, Douglas S
Hydrogenation Dynamics of Biphenylene Carbon (Graphenylene) Membranes Journal Article
Em: MRS Advances, vol. 2017, pp. 1-6, 2017.
@article{Splugues2017,
title = {Hydrogenation Dynamics of Biphenylene Carbon (Graphenylene) Membranes},
author = {Splugues, Vinicius and da Silva Autreto, Pedro Alves and Galvao, Douglas S},
url = {https://www.cambridge.org/core/journals/mrs-advances/article/hydrogenation-dynamics-of-biphenylene-carbon-graphenylene-membranes/139DB900D41560D64F352A31CE219D3A},
doi = {10.1557/adv.2017.239},
year = {2017},
date = {2017-02-28},
journal = {MRS Advances},
volume = {2017},
pages = {1-6},
abstract = {The advent of graphene created a revolution in materials science. Because of this there is a renewed interest in other carbon-based structures. Graphene is the ultimate (just one atom thick) membrane. It has been proposed that graphene can work as impermeable membrane to standard gases, such argon and helium. Graphene-like porous membranes, but presenting larger porosity and potential selectivity would have many technological applications. Biphenylene carbon (BPC), sometimes called graphenylene, is one of these structures. BPC is a porous two-dimensional (planar) allotrope carbon, with its pores resembling typical sieve cavities and/or some kind of zeolites. In this work, we have investigated the hydrogenation dynamics of BPC membranes under different conditions (hydrogenation plasma density, temperature, etc.). We have carried out an extensive study through fully atomistic molecular dynamics (MD) simulations using the reactive force field ReaxFF, as implemented in the well-known Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code. Our results show that the BPC hydrogenation processes exhibit very complex patterns and the formation of correlated domains (hydrogenated islands) observed in the case of graphene hydrogenation was also observed here. MD results also show that under hydrogenation BPC structure undergoes a change in its topology, the pores undergoing structural transformations and extensive hydrogenation can produce significant structural damages, with the formation of large defective areas and large structural holes, leading to structural collapse.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The advent of graphene created a revolution in materials science. Because of this there is a renewed interest in other carbon-based structures. Graphene is the ultimate (just one atom thick) membrane. It has been proposed that graphene can work as impermeable membrane to standard gases, such argon and helium. Graphene-like porous membranes, but presenting larger porosity and potential selectivity would have many technological applications. Biphenylene carbon (BPC), sometimes called graphenylene, is one of these structures. BPC is a porous two-dimensional (planar) allotrope carbon, with its pores resembling typical sieve cavities and/or some kind of zeolites. In this work, we have investigated the hydrogenation dynamics of BPC membranes under different conditions (hydrogenation plasma density, temperature, etc.). We have carried out an extensive study through fully atomistic molecular dynamics (MD) simulations using the reactive force field ReaxFF, as implemented in the well-known Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code. Our results show that the BPC hydrogenation processes exhibit very complex patterns and the formation of correlated domains (hydrogenated islands) observed in the case of graphene hydrogenation was also observed here. MD results also show that under hydrogenation BPC structure undergoes a change in its topology, the pores undergoing structural transformations and extensive hydrogenation can produce significant structural damages, with the formation of large defective areas and large structural holes, leading to structural collapse.
77.
Borges, Daiane Damasceno; Maurin, Guillaume; Galvao, Douglas S
Design of Porous Metal-Organic Frameworks for Adsorption Driven Thermal Batteries Journal Article
Em: MRS Advances, vol. 2017, pp. 1-6, 2017.
@article{Borges2017b,
title = {Design of Porous Metal-Organic Frameworks for Adsorption Driven Thermal Batteries},
author = {Borges, Daiane Damasceno and Maurin, Guillaume and Galvao, Douglas S},
url = {https://www.cambridge.org/core/journals/mrs-advances/article/design-of-porous-metalorganic-frameworks-for-adsorption-driven-thermal-batteries/A63B92E4D7E413D7CC047E152C7F22AF},
doi = {10.1557/adv.2017.181},
year = {2017},
date = {2017-02-15},
journal = {MRS Advances},
volume = {2017},
pages = {1-6},
abstract = {Thermal batteries based on a reversible adsorption/desorption of a working fluid (water, methanol, ammonia) rather than the conventional vapor compression is a promising alternative to exploit waste thermal energy for heat reallocation. In this context, there is an increasing interest to find novel porous solids able to adsorb a high energy density of working fluid under low relative vapor pressure condition combined with an easy ability of regeneration (desorption) at low temperature, which are the major requirements for adsorption driven heat pumps and chillers. The porous crystalline hybrid materials named Metal–Organic Frameworks (MOF) represent a great source of inspiration for sorption based-applications owing to their tunable chemical and topological features associated with a large variability of pore sizes. Recently, we have designed a new MOF named MIL-160 (MIL stands for Materials of Institut Lavoisier), isostructural to CAU-10, built from the assembly of corner sharing aluminum chains octahedra AlO4(OH)2 with the 2,5-furandicarboxylic linker substituting the pristine organic linker, 1,4-benzenedicarboxylate. This ligand replacement strategy proved to enhance both the hydrophilicity of the MOF and its amount of water adsorbed at low p/p0. This designed solid was synthesized and its chemical stability/adsorption performances verified. Here, we have extended this study by incorporating other polar heterocyclic linkers and a comparative computational study of the water adsorption performances of these novel structures has been performed. To that purpose, the cell and geometry optimizations of all hypothetical frameworks were first performed at the density functional theory level and their water adsorption isotherms were further predicted by using force-field based Grand-Canonical Monte Carlo simulations. This study reveals the ease tunable water affinity of MOF for the desired application.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Thermal batteries based on a reversible adsorption/desorption of a working fluid (water, methanol, ammonia) rather than the conventional vapor compression is a promising alternative to exploit waste thermal energy for heat reallocation. In this context, there is an increasing interest to find novel porous solids able to adsorb a high energy density of working fluid under low relative vapor pressure condition combined with an easy ability of regeneration (desorption) at low temperature, which are the major requirements for adsorption driven heat pumps and chillers. The porous crystalline hybrid materials named Metal–Organic Frameworks (MOF) represent a great source of inspiration for sorption based-applications owing to their tunable chemical and topological features associated with a large variability of pore sizes. Recently, we have designed a new MOF named MIL-160 (MIL stands for Materials of Institut Lavoisier), isostructural to CAU-10, built from the assembly of corner sharing aluminum chains octahedra AlO4(OH)2 with the 2,5-furandicarboxylic linker substituting the pristine organic linker, 1,4-benzenedicarboxylate. This ligand replacement strategy proved to enhance both the hydrophilicity of the MOF and its amount of water adsorbed at low p/p0. This designed solid was synthesized and its chemical stability/adsorption performances verified. Here, we have extended this study by incorporating other polar heterocyclic linkers and a comparative computational study of the water adsorption performances of these novel structures has been performed. To that purpose, the cell and geometry optimizations of all hypothetical frameworks were first performed at the density functional theory level and their water adsorption isotherms were further predicted by using force-field based Grand-Canonical Monte Carlo simulations. This study reveals the ease tunable water affinity of MOF for the desired application.
78.
Bizao, Rafael A; Botari, Tiago; Perim, Eric; Pugno, Nicola M; Galvao, Douglas S
Mechanical Properties and Fracture Patterns of Graphene (Graphitic) Nanowiggles Online
2017, (preprint arXiv:1702.01100).
@online{Bizao2017,
title = {Mechanical Properties and Fracture Patterns of Graphene (Graphitic) Nanowiggles},
author = {Bizao, Rafael A and Botari, Tiago and Perim, Eric and Pugno, Nicola M and Galvao, Douglas S},
url = {https://arxiv.org/pdf/1702.01100.pdf},
year = {2017},
date = {2017-02-03},
abstract = {Graphene nanowiggles (GNW) are graphene-based nanostructures
obtained by making alternated regular cuts in pristine graphene nanoribbons.
GNW were recently synthesized and it was demonstrated that
they exhibit tunable electronic and magnetic properties by just varying
their shape. Here, we have investigated the mechanical properties and
fracture patterns of a large number of GNW of different shapes and
sizes using fully atomistic reactive molecular dynamics simulations.
Our results show that the GNW mechanical properties are strongly
dependent on its shape and size and, as a general trend narrow sheets
have larger ultimate strength and Young’s modulus than wide ones.
The estimated Young’s modulus values were found to be in a range of
≈ 100 − 1000 GPa and the ultimate strength in a range of ≈ 20 − 110
GPa, depending on GNW shape. Also, super-ductile behaviour under
strain was observed for some structures.},
note = {preprint arXiv:1702.01100},
keywords = {},
pubstate = {published},
tppubtype = {online}
}
Graphene nanowiggles (GNW) are graphene-based nanostructures
obtained by making alternated regular cuts in pristine graphene nanoribbons.
GNW were recently synthesized and it was demonstrated that
they exhibit tunable electronic and magnetic properties by just varying
their shape. Here, we have investigated the mechanical properties and
fracture patterns of a large number of GNW of different shapes and
sizes using fully atomistic reactive molecular dynamics simulations.
Our results show that the GNW mechanical properties are strongly
dependent on its shape and size and, as a general trend narrow sheets
have larger ultimate strength and Young’s modulus than wide ones.
The estimated Young’s modulus values were found to be in a range of
≈ 100 − 1000 GPa and the ultimate strength in a range of ≈ 20 − 110
GPa, depending on GNW shape. Also, super-ductile behaviour under
strain was observed for some structures.
obtained by making alternated regular cuts in pristine graphene nanoribbons.
GNW were recently synthesized and it was demonstrated that
they exhibit tunable electronic and magnetic properties by just varying
their shape. Here, we have investigated the mechanical properties and
fracture patterns of a large number of GNW of different shapes and
sizes using fully atomistic reactive molecular dynamics simulations.
Our results show that the GNW mechanical properties are strongly
dependent on its shape and size and, as a general trend narrow sheets
have larger ultimate strength and Young’s modulus than wide ones.
The estimated Young’s modulus values were found to be in a range of
≈ 100 − 1000 GPa and the ultimate strength in a range of ≈ 20 − 110
GPa, depending on GNW shape. Also, super-ductile behaviour under
strain was observed for some structures.
79.
Borges, Daiane D; Woellner, Cristiano F; Autreto, Pedro AS; Galvao, Douglas S
2017, (preprint arXiv:1702.00250).
@online{Borges2017,
title = {Water Permeation through Layered Graphene-based Membranes: A Fully Atomistic Molecular Dynamics Investigation},
author = {Borges, Daiane D and Woellner, Cristiano F and Autreto, Pedro AS and Galvao, Douglas S},
url = {https://arxiv.org/abs/1702.00250},
year = {2017},
date = {2017-02-01},
abstract = {Graphene-based membranes have been investigated as promising candidates for water
filtration and gas separation applications. Experimental evidences have shown that graphene
oxide can be impermeable to liquids, vapors and gases, while allowing a fast permeation of water
molecules. This phenomenon has been attributed to the formation of a network of nano
capillaries that allow nearly frictionless water flow while blocking other molecules by steric
hindrance effects. It is supposed that water molecules are transported through the percolated twodimensional
channels formed between graphene-based sheets. Although these channels allow
fast water permeation in such materials, the flow rates are strongly dependent on how the
membranes are fabricated. Also, some fundamental issues regarding the nanoscale mechanisms
of water permeation are still not fully understood and their interpretation remains controversial.
In this work, we have investigated the dynamics of water permeation through pristine graphene
and graphene oxide model membranes. We have carried out fully atomistic classical molecular
dynamics simulations of systems composed of multiple layered graphene-based sheets into
contact with a water reservoir under controlled thermodynamics conditions (e. g., by varying
temperature and pressure values). We have systematically analyzed how the transport dynamics
of the confined nanofluids depend on the interlayer distances and the role of the oxide functional
groups. Our results show the water flux is much more effective for graphene than for graphene
oxide membranes. These results are attributed to the H-bonds formation between oxide
functional groups and water, which traps the water molecules and precludes ultrafast water
transport through the nanochannels.},
note = {preprint arXiv:1702.00250},
keywords = {},
pubstate = {published},
tppubtype = {online}
}
Graphene-based membranes have been investigated as promising candidates for water
filtration and gas separation applications. Experimental evidences have shown that graphene
oxide can be impermeable to liquids, vapors and gases, while allowing a fast permeation of water
molecules. This phenomenon has been attributed to the formation of a network of nano
capillaries that allow nearly frictionless water flow while blocking other molecules by steric
hindrance effects. It is supposed that water molecules are transported through the percolated twodimensional
channels formed between graphene-based sheets. Although these channels allow
fast water permeation in such materials, the flow rates are strongly dependent on how the
membranes are fabricated. Also, some fundamental issues regarding the nanoscale mechanisms
of water permeation are still not fully understood and their interpretation remains controversial.
In this work, we have investigated the dynamics of water permeation through pristine graphene
and graphene oxide model membranes. We have carried out fully atomistic classical molecular
dynamics simulations of systems composed of multiple layered graphene-based sheets into
contact with a water reservoir under controlled thermodynamics conditions (e. g., by varying
temperature and pressure values). We have systematically analyzed how the transport dynamics
of the confined nanofluids depend on the interlayer distances and the role of the oxide functional
groups. Our results show the water flux is much more effective for graphene than for graphene
oxide membranes. These results are attributed to the H-bonds formation between oxide
functional groups and water, which traps the water molecules and precludes ultrafast water
transport through the nanochannels.
filtration and gas separation applications. Experimental evidences have shown that graphene
oxide can be impermeable to liquids, vapors and gases, while allowing a fast permeation of water
molecules. This phenomenon has been attributed to the formation of a network of nano
capillaries that allow nearly frictionless water flow while blocking other molecules by steric
hindrance effects. It is supposed that water molecules are transported through the percolated twodimensional
channels formed between graphene-based sheets. Although these channels allow
fast water permeation in such materials, the flow rates are strongly dependent on how the
membranes are fabricated. Also, some fundamental issues regarding the nanoscale mechanisms
of water permeation are still not fully understood and their interpretation remains controversial.
In this work, we have investigated the dynamics of water permeation through pristine graphene
and graphene oxide model membranes. We have carried out fully atomistic classical molecular
dynamics simulations of systems composed of multiple layered graphene-based sheets into
contact with a water reservoir under controlled thermodynamics conditions (e. g., by varying
temperature and pressure values). We have systematically analyzed how the transport dynamics
of the confined nanofluids depend on the interlayer distances and the role of the oxide functional
groups. Our results show the water flux is much more effective for graphene than for graphene
oxide membranes. These results are attributed to the H-bonds formation between oxide
functional groups and water, which traps the water molecules and precludes ultrafast water
transport through the nanochannels.
80.
Solis, Daniel; Woellner, Cristiano F; Borges, Daiane D; Galvao, Douglas S
Mechanical and Thermal Stability of Graphyne and Graphdiyne Nanoscrolls Journal Article
Em: MRS Advances, vol. 2017, pp. 129-134, 2017.
@article{Solis2017,
title = {Mechanical and Thermal Stability of Graphyne and Graphdiyne Nanoscrolls},
author = {Solis, Daniel and Woellner, Cristiano F and Borges, Daiane D and Galvao, Douglas S},
url = {https://www.cambridge.org/core/journals/mrs-advances/article/mechanical-and-thermal-stability-of-graphyne-and-graphdiyne-nanoscrolls/202E7B7C471411200DE9D05C264726B8},
doi = {10.1557/adv.2017.130},
year = {2017},
date = {2017-02-01},
journal = {MRS Advances},
volume = {2017},
pages = {129-134},
abstract = {Graphynes and graphdiynes are carbon 2D allotrope structures presenting both sp2 and sp hybridized atoms. These materials have been theoretically predicted but due to intrinsic difficulties in their synthesis, only recently some of these structures have been experimentally realized. Graphyne nanoscrolls are structures obtained by rolling up graphyne sheets into papyrus-like structures. In this work, we have investigated, through fully atomistic reactive molecular dynamics simulations, the dynamics of nanoscroll formation for a series of graphyne (α, β, and δ types) structures. We have also investigated their thermal stability for a temperature range of 200-1000K. Our results show that stable nanoscrolls can be formed for all structures considered here. Their stability depends on a critical value of the ratio between length and height of the graphyne sheets. Our findings also show that these structures are structurally less stable then graphene-based nanoscrolls. This can be explained by the graphyne higher structural porosity which results in a decreased pi-pi stacking interactions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Graphynes and graphdiynes are carbon 2D allotrope structures presenting both sp2 and sp hybridized atoms. These materials have been theoretically predicted but due to intrinsic difficulties in their synthesis, only recently some of these structures have been experimentally realized. Graphyne nanoscrolls are structures obtained by rolling up graphyne sheets into papyrus-like structures. In this work, we have investigated, through fully atomistic reactive molecular dynamics simulations, the dynamics of nanoscroll formation for a series of graphyne (α, β, and δ types) structures. We have also investigated their thermal stability for a temperature range of 200-1000K. Our results show that stable nanoscrolls can be formed for all structures considered here. Their stability depends on a critical value of the ratio between length and height of the graphyne sheets. Our findings also show that these structures are structurally less stable then graphene-based nanoscrolls. This can be explained by the graphyne higher structural porosity which results in a decreased pi-pi stacking interactions.
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