Todas as Publicações do INCT-MI – INCT – Institutos Nacionais de Ciência e Tecnologia

237 entradas « ‹ 1 de 12 › »
1.
Piero, João V B Del; Miwa, Roberto H.; Scopel, Wanderlã L.
Vanadium incorporation in 2D-layered MoSe2 Journal Article
Em: J. Phys.: Condens. Matter, vol. 37, não 4, 2025, ISSN: 1361-648X.
Resumo | Links | BibTeX | Tags:
@article{DelPiero2024,
title = {Vanadium incorporation in 2D-layered MoSe2},
author = {João V B Del Piero and Roberto H. Miwa and Wanderlã L. Scopel},
url = {https://iopscience.iop.org/article/10.1088/1361-648X/ad8abb/meta},
doi = {10.1088/1361-648x/ad8abb},
issn = {1361-648X},
year = {2025},
date = {2025-11-11},
urldate = {2025-01-27},
journal = {J. Phys.: Condens. Matter},
volume = {37},
number = {4},
publisher = {IOP Publishing},
abstract = {Recent advances in experimental techniques have made it possible to manipulate the structural and electronic properties of two-dimensional layered materials (2DM) through interaction with foreign atoms. Using quantum mechanics calculations based on the density functional theory, we explored the dependency of the structural, energetic, electronic, and magnetic properties of the interaction between Vanadium (V) atoms and monolayer and bilayer MoSe2. Spin-polarized metallic behavior was observed for high V concentration, and a semiconductor/metal interface emerged due to V adsorption on top of BL MoSe2. Our research demonstrated that the functionalization of 2D materials makes an important contribution to the design of spintronic devices based on a 2D-layered materials platform.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

Fechar
Recent advances in experimental techniques have made it possible to manipulate the structural and electronic properties of two-dimensional layered materials (2DM) through interaction with foreign atoms. Using quantum mechanics calculations based on the density functional theory, we explored the dependency of the structural, energetic, electronic, and magnetic properties of the interaction between Vanadium (V) atoms and monolayer and bilayer MoSe2. Spin-polarized metallic behavior was observed for high V concentration, and a semiconductor/metal interface emerged due to V adsorption on top of BL MoSe2. Our research demonstrated that the functionalization of 2D materials makes an important contribution to the design of spintronic devices based on a 2D-layered materials platform.
Fechar
https://iopscience.iop.org/article/10.1088/1361-648X/ad8abb/meta
doi:10.1088/1361-648x/ad8abb
Fechar
2.
Ullah, Saif; Thonhauser, Timo; Menezes, Marcos G.
Optoelectronic properties of novel layered materials under encapsulation: 2D Copper Iodide and Silver Iodide Journal Article
Em: Applied Materials Today, vol. 41, 2024, ISSN: 2352-9407.
Resumo | Links | BibTeX | Tags:
@article{Ullah2024,
title = {Optoelectronic properties of novel layered materials under encapsulation: 2D Copper Iodide and Silver Iodide},
author = {Saif Ullah and Timo Thonhauser and Marcos G. Menezes},
doi = {10.1016/j.apmt.2024.102495},
issn = {2352-9407},
year = {2024},
date = {2024-12-00},
urldate = {2024-12-00},
journal = {Applied Materials Today},
volume = {41},
publisher = {Elsevier BV},
abstract = {Many novel freestanding two-dimensional materials can be stabilized when placed over a proper substrate or put under encapsulation. Among the different possibilities, graphene and h-BN are commonly used due to their availability and compatibility. In that scenario, it is important to understand how the possible interactions between the core and substrate/encapsulating layers as well as the lattice mismatch affect the optoelectronic properties of the core material. In this work, we use ab initio calculations to study the structural and optolectronic properties of the recently synthesized 2D CuI and AgI layers, which are stabilized under graphene encapsulation (Mustonen et al. (2022)). In addition, the possibility of h-BN encapsulation is also explored. We find that the optoelectronic properties of the core materials are greatly preserved under encapsulation—especially under h-BN. Their bandgaps suffer small variations that mainly originate from the internal strain that results from supercell relaxation. We also see a rehybridization of the electronic bands from the core material whenever they cross or lie close to bands from the encapsulating layers, as expected. This effect is particularly strong for graphene encapsulation. The optical absorption profiles show a combination of features coming from the spectra of the isolated layers with minor modifications introduced by these effects. In particular, a strong and broad absorption is seen in the UV range when using h-BN. Finally, we study a possible CuI-AgI heterobilayer, both isolated and under encapsulation. Interestingly, the structure presents a type-II band alignment that is well preserved under encapsulation, with potential applications in novel photovoltaic devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

Fechar
Many novel freestanding two-dimensional materials can be stabilized when placed over a proper substrate or put under encapsulation. Among the different possibilities, graphene and h-BN are commonly used due to their availability and compatibility. In that scenario, it is important to understand how the possible interactions between the core and substrate/encapsulating layers as well as the lattice mismatch affect the optoelectronic properties of the core material. In this work, we use ab initio calculations to study the structural and optolectronic properties of the recently synthesized 2D CuI and AgI layers, which are stabilized under graphene encapsulation (Mustonen et al. (2022)). In addition, the possibility of h-BN encapsulation is also explored. We find that the optoelectronic properties of the core materials are greatly preserved under encapsulation—especially under h-BN. Their bandgaps suffer small variations that mainly originate from the internal strain that results from supercell relaxation. We also see a rehybridization of the electronic bands from the core material whenever they cross or lie close to bands from the encapsulating layers, as expected. This effect is particularly strong for graphene encapsulation. The optical absorption profiles show a combination of features coming from the spectra of the isolated layers with minor modifications introduced by these effects. In particular, a strong and broad absorption is seen in the UV range when using h-BN. Finally, we study a possible CuI-AgI heterobilayer, both isolated and under encapsulation. Interestingly, the structure presents a type-II band alignment that is well preserved under encapsulation, with potential applications in novel photovoltaic devices.
Fechar
doi:10.1016/j.apmt.2024.102495
Fechar
3.
Stoco, Caroline Binde; Cassar, Daniel R.; Santana, Geovana Lira; Kaufman, Michael; Clarke, Amy; Coury, Francisco Gil
Optimizing toughness in high entropy alloys using a genetic algorithm: A combined computational and experimental approach Journal Article
Em: Materials Today Communications, vol. 41, 2024, ISSN: 2352-4928.
Resumo | Links | BibTeX | Tags:
@article{Stoco2024,
title = {Optimizing toughness in high entropy alloys using a genetic algorithm: A combined computational and experimental approach},
author = {Caroline Binde Stoco and Daniel R. Cassar and Geovana Lira Santana and Michael Kaufman and Amy Clarke and Francisco Gil Coury},
doi = {10.1016/j.mtcomm.2024.110768},
issn = {2352-4928},
year = {2024},
date = {2024-12-00},
urldate = {2024-12-00},
journal = {Materials Today Communications},
volume = {41},
publisher = {Elsevier BV},
abstract = {A genetic algorithm (GA) was developed to search for high entropy alloys (HEAs) with good combinations of mechanical properties. The algorithm was designed find single-phase face-centered cubic (FCC) HEAs, already known for their ductility, with high Hall-Petch constants (K) and high critical resolved shear stresses (
). The objective was to develop a methodology that allows the design of HEAs in a multi-objective environment, focusing on alloys that exhibit enhanced ductility and strength, achieved through an increase in its yield point without significant loss of its ultimate deformation via adjustments of K and
values, resulting in an alloy with high toughness. The most promising alloy suggested by the genetic algorithm was an unconventional composition (Co32.73Cu15.11Fe0.72Hf0.72Mn35.97Mo3.96Ni10.43Sn0.36), with eight different elements in non-equiatomic ratios with maximized K and
values. This alloy was then experimentally produced and characterized by scanning electron microscopy (SEM), synchrotron x-ray diffraction (XRD), transmission electron microscopy (TEM) and microhardness, with the objective of validating the predictions made by the GA. An advantage of the proposed method is the possibility of more systematically identifying and exploring new compositions in the complex composition space characteristic of these multicomponent alloys, as it directs its search towards domains that can be used to solve challenging problems involving multi-objective optimization. However, the thermodynamic parameters used for single-phase FCC prediction, namely the valence electron concentration (VEC) and the dimensionless thermodynamic parameter φ, exhibited limitations. These limitations were further explored in the present study, as evidenced by the fact that the microstructure of the selected alloy was not single-phase, which hindered the study of the mechanical properties, predicted exclusively for monophasic FCC alloys. Therefore, this work highlights the necessity for the development of novel thermodynamic equations for phase prediction, or even the integration of the genetic algorithm with other methodologies, such as CALPHAD calculations, to achieve enhanced results.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

Fechar
A genetic algorithm (GA) was developed to search for high entropy alloys (HEAs) with good combinations of mechanical properties. The algorithm was designed find single-phase face-centered cubic (FCC) HEAs, already known for their ductility, with high Hall-Petch constants (K) and high critical resolved shear stresses (
). The objective was to develop a methodology that allows the design of HEAs in a multi-objective environment, focusing on alloys that exhibit enhanced ductility and strength, achieved through an increase in its yield point without significant loss of its ultimate deformation via adjustments of K and
values, resulting in an alloy with high toughness. The most promising alloy suggested by the genetic algorithm was an unconventional composition (Co32.73Cu15.11Fe0.72Hf0.72Mn35.97Mo3.96Ni10.43Sn0.36), with eight different elements in non-equiatomic ratios with maximized K and
values. This alloy was then experimentally produced and characterized by scanning electron microscopy (SEM), synchrotron x-ray diffraction (XRD), transmission electron microscopy (TEM) and microhardness, with the objective of validating the predictions made by the GA. An advantage of the proposed method is the possibility of more systematically identifying and exploring new compositions in the complex composition space characteristic of these multicomponent alloys, as it directs its search towards domains that can be used to solve challenging problems involving multi-objective optimization. However, the thermodynamic parameters used for single-phase FCC prediction, namely the valence electron concentration (VEC) and the dimensionless thermodynamic parameter φ, exhibited limitations. These limitations were further explored in the present study, as evidenced by the fact that the microstructure of the selected alloy was not single-phase, which hindered the study of the mechanical properties, predicted exclusively for monophasic FCC alloys. Therefore, this work highlights the necessity for the development of novel thermodynamic equations for phase prediction, or even the integration of the genetic algorithm with other methodologies, such as CALPHAD calculations, to achieve enhanced results.
Fechar
doi:10.1016/j.mtcomm.2024.110768
Fechar
4.
Hostert, Leandro; Dias, Matheus S.; de Aquino, Caroline B.; dos Santos, Felipe C.; Marangoni, Valéria S.; de Carvalho C Silva, Cecília; Seixas, Leandro; Maroneze, Camila M.
Covalent Surface Functionalization of Exfoliated MoS2 Nanosheets for Improved Electrocatalysis Journal Article
Em: J. Phys. Chem. C, 2024, ISSN: 1932-7455.
Resumo | Links | BibTeX | Tags:
@article{Hostert2024,
title = {Covalent Surface Functionalization of Exfoliated MoS2 Nanosheets for Improved Electrocatalysis},
author = {Leandro Hostert and Matheus S. Dias and Caroline B. de Aquino and Felipe C. dos Santos and Valéria S. Marangoni and Cecília de Carvalho C Silva and Leandro Seixas and Camila M. Maroneze},
doi = {10.1021/acs.jpcc.4c05965},
issn = {1932-7455},
year = {2024},
date = {2024-11-13},
urldate = {2024-11-13},
journal = {J. Phys. Chem. C},
publisher = {American Chemical Society (ACS)},
abstract = {Transition metal dichalcogenides, particularly the metallic phase of molybdenum disulfide (1T’-MoS2), have attracted significant attention as promising nonprecious metal electrocatalysts for the hydrogen evolution reaction (HER) due to their appealing electrochemical properties and optimal hydrogen adsorption free energy (ΔGH). In this study, we used a combined theoretical and experimental approach to investigate the covalent functionalization of MoS2 with −CH2COOH groups. Notably, the presence of Mo oxidized species(MoOx) was significantly diminished in the functionalized material, suggesting a potential protective role of the functional groups against MoS2 oxidation. Additionally, our findings show a decrease in the proportion of the metallic 1T’ phase upon functionalization (58% for MoS2/CH2COOH compared to 74% for Exf-MoS2). However, electrochemical measurements unveil a remarkable enhancement in electrocatalytic activity upon the integration of −CH2COOH groups, as evidenced by observations from Linear Sweep Voltammetry (LSV) and Electrochemical Impedance Spectroscopy (EIS). In LSV analysis, a substantial 53% reduction in the Tafel slope is observed, declining from −145 mV dec–1 (for Exf-MoS2) to −77 mV dec–1 (for MoS2/CH2COOH). Additionally, EIS measurements indicate a significant decrease in charge transfer resistance, dropping from 82.03 ± 0.11 kΩ/cm2 (for Exf-MoS2) to 12.41 ± 0.01 kΩ/cm2 (for MoS2/CH2COOH). The integration of these functional groups onto the MoS2 surface demonstrates remarkable effectiveness in inhibiting oxidation while concurrently leading to a noteworthy enhancement of catalytic activity for the HER.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

Fechar
Transition metal dichalcogenides, particularly the metallic phase of molybdenum disulfide (1T’-MoS2), have attracted significant attention as promising nonprecious metal electrocatalysts for the hydrogen evolution reaction (HER) due to their appealing electrochemical properties and optimal hydrogen adsorption free energy (ΔGH). In this study, we used a combined theoretical and experimental approach to investigate the covalent functionalization of MoS2 with −CH2COOH groups. Notably, the presence of Mo oxidized species(MoOx) was significantly diminished in the functionalized material, suggesting a potential protective role of the functional groups against MoS2 oxidation. Additionally, our findings show a decrease in the proportion of the metallic 1T’ phase upon functionalization (58% for MoS2/CH2COOH compared to 74% for Exf-MoS2). However, electrochemical measurements unveil a remarkable enhancement in electrocatalytic activity upon the integration of −CH2COOH groups, as evidenced by observations from Linear Sweep Voltammetry (LSV) and Electrochemical Impedance Spectroscopy (EIS). In LSV analysis, a substantial 53% reduction in the Tafel slope is observed, declining from −145 mV dec–1 (for Exf-MoS2) to −77 mV dec–1 (for MoS2/CH2COOH). Additionally, EIS measurements indicate a significant decrease in charge transfer resistance, dropping from 82.03 ± 0.11 kΩ/cm2 (for Exf-MoS2) to 12.41 ± 0.01 kΩ/cm2 (for MoS2/CH2COOH). The integration of these functional groups onto the MoS2 surface demonstrates remarkable effectiveness in inhibiting oxidation while concurrently leading to a noteworthy enhancement of catalytic activity for the HER.
Fechar
doi:10.1021/acs.jpcc.4c05965
Fechar
5.
Lyu, Peifen; Matusalem, Filipe; Deniz, Ece; Rocha, Alexandre Reily; Leite, Marina S.
In Situ Solid-State Dewetting of Ag–Au–Pd Alloy: From Macro- to Nanoscale Journal Article
Em: ACS Appl. Mater. Interfaces, vol. 16, não 45, pp. 62860–62870, 2024, ISSN: 1944-8252.
Resumo | Links | BibTeX | Tags:
@article{Lyu2024,
title = {In Situ Solid-State Dewetting of Ag–Au–Pd Alloy: From Macro- to Nanoscale},
author = {Peifen Lyu and Filipe Matusalem and Ece Deniz and Alexandre Reily Rocha and Marina S. Leite},
doi = {10.1021/acsami.4c11397},
issn = {1944-8252},
year = {2024},
date = {2024-11-13},
urldate = {2024-11-13},
journal = {ACS Appl. Mater. Interfaces},
volume = {16},
number = {45},
pages = {62860--62870},
publisher = {American Chemical Society (ACS)},
abstract = {etal alloy nanostructures represent a promising platform for next-generation nanophotonic devices, surpassing the limitations of pure metals by offering additional “buttons” for tailoring their optical properties by compositional variations. While alloyed nanoparticles hold great potential, their scalability and underexplored optical behavior still limit their application. Here, we establish a systematic approach to quantifying the unique optical behavior of the AgAuPd ternary system while providing a direct comparison with its pure constituent metals. Computationally, we analyze their electronic structure and uncover the transition of Pd d states to Pd/Ag hybridized s states in the bulk form, explaining the similar optical properties observed between Pd and AgAuPd. Experimentally, we fabricate pure metal and fully alloyed nanoparticles through solid-state dewetting, a scalable method. During the process, we trace the optical transition in the systems from the initial thin film stage to the final nanoparticle stage with in situ ellipsometry. We reveal the interplay between optical properties influenced by chemical interdiffusion and localized surface plasmon resonance arising from morphological changes with ex situ surface characterizations. Additionally, we analytically implement a metallic layer derived from the ternary system in a trilayer device, resulting in a single-time and irreversible color filter, to demonstrate an application encompassing a lithography-free and cost-effective route for nanophotonic devices.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

Fechar
etal alloy nanostructures represent a promising platform for next-generation nanophotonic devices, surpassing the limitations of pure metals by offering additional “buttons” for tailoring their optical properties by compositional variations. While alloyed nanoparticles hold great potential, their scalability and underexplored optical behavior still limit their application. Here, we establish a systematic approach to quantifying the unique optical behavior of the AgAuPd ternary system while providing a direct comparison with its pure constituent metals. Computationally, we analyze their electronic structure and uncover the transition of Pd d states to Pd/Ag hybridized s states in the bulk form, explaining the similar optical properties observed between Pd and AgAuPd. Experimentally, we fabricate pure metal and fully alloyed nanoparticles through solid-state dewetting, a scalable method. During the process, we trace the optical transition in the systems from the initial thin film stage to the final nanoparticle stage with in situ ellipsometry. We reveal the interplay between optical properties influenced by chemical interdiffusion and localized surface plasmon resonance arising from morphological changes with ex situ surface characterizations. Additionally, we analytically implement a metallic layer derived from the ternary system in a trilayer device, resulting in a single-time and irreversible color filter, to demonstrate an application encompassing a lithography-free and cost-effective route for nanophotonic devices.
Fechar
doi:10.1021/acsami.4c11397
Fechar
6.
Milošević, Milorad V.; Covaci, Lucian
Bright excitons in black phosphorus Journal Article
Em: Science, vol. 386, não 6721, pp. 493–494, 2024, ISSN: 1095-9203.
Resumo | Links | BibTeX | Tags:
@article{Milošević2024,
title = {Bright excitons in black phosphorus},
author = {Milorad V. Milošević and Lucian Covaci},
doi = {10.1126/science.adt0451},
issn = {1095-9203},
year = {2024},
date = {2024-11-00},
urldate = {2024-11-00},
journal = {Science},
volume = {386},
number = {6721},
pages = {493--494},
publisher = {American Association for the Advancement of Science (AAAS)},
abstract = {Excitons—neutral bound states of electron and hole pairs—are essential to the optoelectronic behavior of semiconductor materials. These “quasiparticles” are generated when incident light is absorbed by a semiconductor, and they can recombine to emit light. Understanding and controlling excitonic behavior is therefore crucial to advancing nanophotonic and quantum optoelectronic technologies. However, presently available materials for such devices often do not exhibit a strong-enough interaction with light and lack tunability. On page 526 of this issue, Huang et al. (1) report the unexpected emergence of strong dipolar excitons in twisted multilayers of black phosphorus. This material exhibits tunable excitonic properties, which could unlock new quantum phenomena and shape future technologies.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

Fechar
Excitons—neutral bound states of electron and hole pairs—are essential to the optoelectronic behavior of semiconductor materials. These “quasiparticles” are generated when incident light is absorbed by a semiconductor, and they can recombine to emit light. Understanding and controlling excitonic behavior is therefore crucial to advancing nanophotonic and quantum optoelectronic technologies. However, presently available materials for such devices often do not exhibit a strong-enough interaction with light and lack tunability. On page 526 of this issue, Huang et al. (1) report the unexpected emergence of strong dipolar excitons in twisted multilayers of black phosphorus. This material exhibits tunable excitonic properties, which could unlock new quantum phenomena and shape future technologies.
Fechar
doi:10.1126/science.adt0451
Fechar
7.
Arvelos, Graciele M.; Fernández-Serra, Marivi; Rocha, Alexandre Reily; Pedroza, Luana S.
Probing Water-Electrified Electrode interfaces: Insights from Au and Pd Working paper
2024.
Resumo | Links | BibTeX | Tags:
@workingpaper{arvelos2024probingwaterelectrifiedelectrodeinterfaces,
title = {Probing Water-Electrified Electrode interfaces: Insights from Au and Pd},
author = {Graciele M. Arvelos and Marivi Fernández-Serra and Alexandre Reily Rocha and Luana S. Pedroza},
url = {https://arxiv.org/abs/2410.24150},
year = {2024},
date = {2024-10-31},
urldate = {2024-01-01},
abstract = {The water/electrode interface under an applied bias potential is a challenging out-of-equilibrium phenomenon, which is difficult to accurately model at the atomic scale. In this study, we employ a combined approach of Density Functional Theory (DFT) and non-equilibrium Green's function (NEGF) methods to analyze the influence of an external bias on the properties of water adsorbed on Au(111) and Pd(111) metallic electrodes. Our results demonstrate that while both Au and Pd-electrodes induce qualitatively similar structural responses in adsorbed water molecules, the quantitative differences are substantial, driven by the distinct nature of water-metal bonding. Our findings underscore the necessity of quantum-mechanical modeling for accurately describing electrochemical interfaces.},
keywords = {},
pubstate = {published},
tppubtype = {workingpaper}
}

Fechar
The water/electrode interface under an applied bias potential is a challenging out-of-equilibrium phenomenon, which is difficult to accurately model at the atomic scale. In this study, we employ a combined approach of Density Functional Theory (DFT) and non-equilibrium Green's function (NEGF) methods to analyze the influence of an external bias on the properties of water adsorbed on Au(111) and Pd(111) metallic electrodes. Our results demonstrate that while both Au and Pd-electrodes induce qualitatively similar structural responses in adsorbed water molecules, the quantitative differences are substantial, driven by the distinct nature of water-metal bonding. Our findings underscore the necessity of quantum-mechanical modeling for accurately describing electrochemical interfaces.
Fechar
https://arxiv.org/abs/2410.24150
Fechar
8.
Vassiliades, Sandra V.; Argüello, Karina A. B.; Castro, Carlos E.; Silva, Clovis A.; Gonzalez, Ana Clara; Homem-de-Mello, Paula; Nantes, Iseli Lourenço; Aguilar, Andrea M.; Barbosa-Reis, Gustavo; Oliveira-Silva, Diogo; Giuntini, Francesca; Alves, Wendel A.
Synthesis, photophysical properties, and photocytotoxic effects of porphyrin-diphenylalanine conjugates on HeLa cells Journal Article
Em: Journal of Molecular Structure, vol. 1322, 2024, ISSN: 0022-2860.
Resumo | Links | BibTeX | Tags:
@article{Vassiliades2025,
title = {Synthesis, photophysical properties, and photocytotoxic effects of porphyrin-diphenylalanine conjugates on HeLa cells},
author = {Sandra V. Vassiliades and Karina A.B. Argüello and Carlos E. Castro and Clovis A. Silva and Ana Clara Gonzalez and Paula Homem-de-Mello and Iseli Lourenço Nantes and Andrea M. Aguilar and Gustavo Barbosa-Reis and Diogo Oliveira-Silva and Francesca Giuntini and Wendel A. Alves},
doi = {10.1016/j.molstruc.2024.140545},
issn = {0022-2860},
year = {2024},
date = {2024-10-30},
urldate = {2025-02-00},
journal = {Journal of Molecular Structure},
volume = {1322},
publisher = {Elsevier BV},
abstract = {Photodynamic therapy (PDT) triggers selective cell death through intensive oxidative stress induced by the generation of reactive species by a photosensitizer (PS) excited by light. In this work, we report the synthesis of four novel porphyrins conjugated to the self-assembling dipeptide L,L-diphenylalanine (FF), effectively inhibiting cervical tumor cell growth. The PS were prepared using the classical A3B strategy, with functionalized and non-functionalized porphyrins obtained in moderate yields over 3 to 4 steps. Absorption and fluorescence studies indicate that the FF attached to the porphyrin ring influences their aggregation at micromolar concentrations. The compounds were efficiently internalized by HeLa cells after 4 h of incubation. Cytotoxicity tests performed in the 1.25–5.0 µmol L−1 range showed that cell viability was reduced to 70 % after irradiation (650 nm). A correlation between cell permeation and the cell death mechanism promoted by the porphyrin was observed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

Fechar
Photodynamic therapy (PDT) triggers selective cell death through intensive oxidative stress induced by the generation of reactive species by a photosensitizer (PS) excited by light. In this work, we report the synthesis of four novel porphyrins conjugated to the self-assembling dipeptide L,L-diphenylalanine (FF), effectively inhibiting cervical tumor cell growth. The PS were prepared using the classical A3B strategy, with functionalized and non-functionalized porphyrins obtained in moderate yields over 3 to 4 steps. Absorption and fluorescence studies indicate that the FF attached to the porphyrin ring influences their aggregation at micromolar concentrations. The compounds were efficiently internalized by HeLa cells after 4 h of incubation. Cytotoxicity tests performed in the 1.25–5.0 µmol L−1 range showed that cell viability was reduced to 70 % after irradiation (650 nm). A correlation between cell permeation and the cell death mechanism promoted by the porphyrin was observed.
Fechar
doi:10.1016/j.molstruc.2024.140545
Fechar
9.
Petry, Romana; de Almeida, James M.; Côa, Francine; de Lima, F. Crasto; Martinez, Diego Stéfani T; Fazzio, Adalberto
Interaction of graphene oxide with tannic acid: computational modeling and toxicity mitigation in C. elegans Journal Article
Em: Beilstein J. Nanotechnol., vol. 15, pp. 1297–1311, 2024, ISSN: 2190-4286.
Resumo | Links | BibTeX | Tags:
@article{Petry2024,
title = {Interaction of graphene oxide with tannic acid: computational modeling and toxicity mitigation in C. elegans},
author = {Romana Petry and James M. de Almeida and Francine Côa and F. Crasto de Lima and Diego Stéfani T Martinez and Adalberto Fazzio},
doi = {10.3762/bjnano.15.105},
issn = {2190-4286},
year = {2024},
date = {2024-10-30},
urldate = {2024-10-30},
journal = {Beilstein J. Nanotechnol.},
volume = {15},
pages = {1297--1311},
publisher = {Beilstein Institut},
abstract = {Graphene oxide (GO) undergoes multiple transformations when introduced to biological and environmental media. GO surface favors the adsorption of biomolecules through different types of interaction mechanisms, modulating the biological effects of the material. In this study, we investigated the interaction of GO with tannic acid (TA) and its consequences for GO toxicity. We focused on understanding how TA interacts with GO, its impact on the material surface chemistry, colloidal stability, as well as, toxicity and biodistribution using the Caenorhabditis elegans model. Employing computational modeling, including reactive classical molecular dynamics and ab initio calculations, we reveal that TA preferentially binds to the most reactive sites on GO surfaces via the oxygen-containing groups or the carbon matrix; van der Waals interaction forces dominate the binding energy. TA exhibits a dose-dependent mitigating effect on the toxicity of GO, which can be attributed not only to the surface interactions between the molecule and the material but also to the inherent biological properties of TA in C. elegans. Our findings contribute to a deeper understanding of GO’s environmental behavior and toxicity and highlight the potential of tannic acid for the synthesis and surface functionalization of graphene-based nanomaterials, offering insights into safer nanotechnology development.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

Fechar
Graphene oxide (GO) undergoes multiple transformations when introduced to biological and environmental media. GO surface favors the adsorption of biomolecules through different types of interaction mechanisms, modulating the biological effects of the material. In this study, we investigated the interaction of GO with tannic acid (TA) and its consequences for GO toxicity. We focused on understanding how TA interacts with GO, its impact on the material surface chemistry, colloidal stability, as well as, toxicity and biodistribution using the Caenorhabditis elegans model. Employing computational modeling, including reactive classical molecular dynamics and ab initio calculations, we reveal that TA preferentially binds to the most reactive sites on GO surfaces via the oxygen-containing groups or the carbon matrix; van der Waals interaction forces dominate the binding energy. TA exhibits a dose-dependent mitigating effect on the toxicity of GO, which can be attributed not only to the surface interactions between the molecule and the material but also to the inherent biological properties of TA in C. elegans. Our findings contribute to a deeper understanding of GO’s environmental behavior and toxicity and highlight the potential of tannic acid for the synthesis and surface functionalization of graphene-based nanomaterials, offering insights into safer nanotechnology development.
Fechar
doi:10.3762/bjnano.15.105
Fechar
10.
Li, Q. N.; Xiao, Y. M.; Xu, W.; Peeters, F. M.; Milošević, Milorad V.
Anisotropic optical conductivity of the 𝑛-doped type-II three-dimensional Dirac semimetal PtTe2 Journal Article
Em: Phys. Rev. B, vol. 110, iss. 16, pp. 165203, 2024.
Resumo | Links | BibTeX | Tags:
@article{PhysRevB.110.165203,
title = {Anisotropic optical conductivity of the 𝑛-doped type-II three-dimensional Dirac semimetal PtTe2},
author = {Q. N. Li and Y. M. Xiao and W. Xu and F. M. Peeters and Milorad V. Milošević},
url = {https://link.aps.org/doi/10.1103/PhysRevB.110.165203},
doi = {10.1103/PhysRevB.110.165203},
year = {2024},
date = {2024-10-14},
urldate = {2024-10-01},
journal = {Phys. Rev. B},
volume = {110},
issue = {16},
pages = {165203},
publisher = {American Physical Society},
abstract = {We analyze theoretically the anisotropic optical conductivity of the 𝑛-doped type-II three-dimensional (3D) Dirac semimetal (DSM) PtTe2. With the effective Hamiltonian, which describes the anisotropic and tilted 3D Dirac cone in bulk PtTe2, the optical conductivities induced by the linearly polarized light are evaluated using the energy-balance equation derived from the Boltzmann equation. The in-plane optical conductivity 𝜎𝑥⁢𝑥⁡(𝜔) is similar to that of isotropic and nontilted Dirac systems, whereas a unique out-of-plane optical conductivity 𝜎𝑧⁢𝑧⁡(𝜔) has been found due to the tilt of the Dirac cone of PtTe2 along the 𝑘𝑧 direction. Both 𝜎𝑥⁢𝑥⁡(𝜔) and 𝜎𝑧⁢𝑧⁡(𝜔) are contributed by intraband and interband electronic transitions, where the interband transitions show more distinct anisotropic properties. We show that both 𝜎𝑥⁢𝑥⁡(𝜔) and 𝜎𝑧⁢𝑧⁡(𝜔) depend sensitively on energy relaxation times, temperature, and electron density, which enables their broad tunability in PtTe2, and promotes tailored applications of this and similar type-II 3D DSMs.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

Fechar
We analyze theoretically the anisotropic optical conductivity of the 𝑛-doped type-II three-dimensional (3D) Dirac semimetal (DSM) PtTe2. With the effective Hamiltonian, which describes the anisotropic and tilted 3D Dirac cone in bulk PtTe2, the optical conductivities induced by the linearly polarized light are evaluated using the energy-balance equation derived from the Boltzmann equation. The in-plane optical conductivity 𝜎𝑥⁢𝑥⁡(𝜔) is similar to that of isotropic and nontilted Dirac systems, whereas a unique out-of-plane optical conductivity 𝜎𝑧⁢𝑧⁡(𝜔) has been found due to the tilt of the Dirac cone of PtTe2 along the 𝑘𝑧 direction. Both 𝜎𝑥⁢𝑥⁡(𝜔) and 𝜎𝑧⁢𝑧⁡(𝜔) are contributed by intraband and interband electronic transitions, where the interband transitions show more distinct anisotropic properties. We show that both 𝜎𝑥⁢𝑥⁡(𝜔) and 𝜎𝑧⁢𝑧⁡(𝜔) depend sensitively on energy relaxation times, temperature, and electron density, which enables their broad tunability in PtTe2, and promotes tailored applications of this and similar type-II 3D DSMs.
Fechar
https://link.aps.org/doi/10.1103/PhysRevB.110.165203
doi:10.1103/PhysRevB.110.165203
Fechar
11.
Sousa, Frederico B.; Matos, Matheus J. S.; Carvalho, Bruno R.; Liu, Mingzu; Ames, Alessandra; Zhou, Da; Resende, Geovani C.; Yu, Zhuohang; Lafeta, Lucas; Pimenta, Marcos A.; Terrones, Mauricio; Teodoro, Marcio D.; Chacham, Helio; Malard, Leandro M.
Giant Valley Zeeman Splitting in Vanadium-Doped WSe2 Monolayers Journal Article
Em: Small, 2024, ISSN: 1613-6829.
Resumo | Links | BibTeX | Tags:
@article{Sousa2024,
title = {Giant Valley Zeeman Splitting in Vanadium-Doped WSe2 Monolayers},
author = {Frederico B. Sousa and Matheus J. S. Matos and Bruno R. Carvalho and Mingzu Liu and Alessandra Ames and Da Zhou and Geovani C. Resende and Zhuohang Yu and Lucas Lafeta and Marcos A. Pimenta and Mauricio Terrones and Marcio D. Teodoro and Helio Chacham and Leandro M. Malard},
url = {https://onlinelibrary.wiley.com/doi/10.1002/smll.202405434},
doi = {10.1002/smll.202405434},
issn = {1613-6829},
year = {2024},
date = {2024-10-08},
urldate = {2024-10-08},
journal = {Small},
publisher = {Wiley},
abstract = {2D dilute magnetic semiconductors (DMS) based on transition metal dichalcogenides (TMD) offer an innovative pathway for advancing spintronic technologies, including the potential to exploit phenomena such as the valley Zeeman effect. However, the impact of magnetic ordering on the valley degeneracy breaking and on the enhancement of the optical transitions g-factors of these materials remains an open question. Here, a giant effective g-factors ranging between ≈−27 and −69 for the bound exciton at 4 K in vanadium-doped WSe2 monolayers, obtained through magneto-photoluminescence (PL) experiments is reported. This giant g-factor disappears at room temperature, suggesting that this response is associated with a magnetic ordering of the vanadium impurity states at low temperatures. Ab initio calculations for the vanadium-doped WSe2 monolayer confirm the existence of magnetic ordering of the vanadium states, which leads to degeneracy breaking of the valence bands at K and K′. A phenomenological analysis is employed to correlate this splitting with the measured enhanced effective g-factor. The findings shed light on the potential of defect engineering of 2D materials for spintronic applications.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

Fechar
2D dilute magnetic semiconductors (DMS) based on transition metal dichalcogenides (TMD) offer an innovative pathway for advancing spintronic technologies, including the potential to exploit phenomena such as the valley Zeeman effect. However, the impact of magnetic ordering on the valley degeneracy breaking and on the enhancement of the optical transitions g-factors of these materials remains an open question. Here, a giant effective g-factors ranging between ≈−27 and −69 for the bound exciton at 4 K in vanadium-doped WSe2 monolayers, obtained through magneto-photoluminescence (PL) experiments is reported. This giant g-factor disappears at room temperature, suggesting that this response is associated with a magnetic ordering of the vanadium impurity states at low temperatures. Ab initio calculations for the vanadium-doped WSe2 monolayer confirm the existence of magnetic ordering of the vanadium states, which leads to degeneracy breaking of the valence bands at K and K′. A phenomenological analysis is employed to correlate this splitting with the measured enhanced effective g-factor. The findings shed light on the potential of defect engineering of 2D materials for spintronic applications.
Fechar
https://onlinelibrary.wiley.com/doi/10.1002/smll.202405434
doi:10.1002/smll.202405434
Fechar
12.
Portugal, Guilherme Ribeiro; Arantes, Jeverson Teodoro
Dimensionality and strain-dependent properties of Orthorhombic (100) NaTaO3 thin films: A comprehensive DFT investigation Journal Article
Em: Computational Materials Science, vol. 245, 2024, ISSN: 0927-0256.
Resumo | Links | BibTeX | Tags:
@article{Portugal2024,
title = {Dimensionality and strain-dependent properties of Orthorhombic (100) NaTaO3 thin films: A comprehensive DFT investigation},
author = {Guilherme Ribeiro Portugal and Jeverson Teodoro Arantes},
url = {https://www.sciencedirect.com/science/article/pii/S0927025624005561},
doi = {10.1016/j.commatsci.2024.113335},
issn = {0927-0256},
year = {2024},
date = {2024-10-00},
urldate = {2024-10-00},
journal = {Computational Materials Science},
volume = {245},
publisher = {Elsevier BV},
abstract = {The modulation of perovskite oxide thin films’ properties, through both intrinsic and extrinsic methods, has been extensively studied to enhance their photocatalytic performance. We employed ab initio density functional theory calculations to investigate the layer-dependent structural and electronic properties of orthorhombic NaTaO
thin films. Our findings reveal that slabs comprising five, four, and three layers retain the non-magnetic and semiconducting characteristics of the bulk material, with their properties progressively converging towards those of an infinite-surface slab as the number of layers increases. Biaxial in-plane strain induces a linear change in the structure of surface TaO
tetrahedra, thereby altering the film’s band gap. Notably, the two-layer slab exhibits a transitional behavior between the bulk-like nature of thicker films and the unique features of a NaTaO
monolayer, showing heightened sensitivity to strain. Under compression, this bilayered system acquires bulk-like properties, whereas its strain-free state is magnetic and metallic akin to the monolayer. Similar transitions are observed in the latter, though under higher compression values. We provide an in-depth discussion of the structural and electronic mechanisms underlying these transitions. Additionally, the relative band-edge alignment with water-splitting photocatalytic potentials underscores the complex interplay between strain and dimensionality. This work offers valuable insights towards the design of more efficient photocatalysts, highlighting the potential of engineered NaTaO
thin-film structures for advancing photocatalytic applications.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

Fechar
The modulation of perovskite oxide thin films’ properties, through both intrinsic and extrinsic methods, has been extensively studied to enhance their photocatalytic performance. We employed ab initio density functional theory calculations to investigate the layer-dependent structural and electronic properties of orthorhombic NaTaO
thin films. Our findings reveal that slabs comprising five, four, and three layers retain the non-magnetic and semiconducting characteristics of the bulk material, with their properties progressively converging towards those of an infinite-surface slab as the number of layers increases. Biaxial in-plane strain induces a linear change in the structure of surface TaO
tetrahedra, thereby altering the film’s band gap. Notably, the two-layer slab exhibits a transitional behavior between the bulk-like nature of thicker films and the unique features of a NaTaO
monolayer, showing heightened sensitivity to strain. Under compression, this bilayered system acquires bulk-like properties, whereas its strain-free state is magnetic and metallic akin to the monolayer. Similar transitions are observed in the latter, though under higher compression values. We provide an in-depth discussion of the structural and electronic mechanisms underlying these transitions. Additionally, the relative band-edge alignment with water-splitting photocatalytic potentials underscores the complex interplay between strain and dimensionality. This work offers valuable insights towards the design of more efficient photocatalysts, highlighting the potential of engineered NaTaO
thin-film structures for advancing photocatalytic applications.
Fechar
https://www.sciencedirect.com/science/article/pii/S0927025624005561
doi:10.1016/j.commatsci.2024.113335
Fechar
13.
Miranda, I. P.; Pankratova, M.; Weißenhofer, M.; Klautau, Angela B.; Thonig, D.; Pereiro, M.; Sjöqvist, E.; Delin, A.; Katsnelson, M. I.; Eriksson, O.; Bergman, A.
Spin-lattice couplings in 3d ferromagnets: analysis from first-principles Miscellaneous
2024.
Resumo | Links | BibTeX | Tags:
@misc{miranda2024spinlatticecouplings3dferromagnets,
title = {Spin-lattice couplings in 3d ferromagnets: analysis from first-principles},
author = {I. P. Miranda and M. Pankratova and M. Weißenhofer and Angela B. Klautau and D. Thonig and M. Pereiro and E. Sjöqvist and A. Delin and M. I. Katsnelson and O. Eriksson and A. Bergman},
url = {https://arxiv.org/abs/2409.18274},
year = {2024},
date = {2024-09-26},
urldate = {2024-09-26},
abstract = {Magnetoelasticity plays a crucial role in numerous magnetic phenomena, including magnetocalorics, magnon excitation via acoustic waves, and ultrafast demagnetization/Einstein-de Haas effect. Despite a long-standing discussion on anisotropy-mediated magnetoelastic interactions of relativistic origin, including textit{ab-initio} calculations, the exchange-mediated magnetoelastic parameters within an atomistic framework have only recently begun to be investigated. As a result, many of their behaviors and values for real materials remain poorly understood. Therefore, by using a proposed simple modification of the embedded cluster approach that reduces the computational complexity, we critically analyze the properties of exchange-mediated spin-lattice coupling parameters for elemental 3d ferromagnets (bcc Fe, fcc Ni, and fcc Co), comparing methods used for their extraction and relating their realistic values to symmetry considerations and orbitally-decomposed contributions. Additionally, we investigate the effects of noncollinearity (spin temperature) and applied pressure on these parameters. For Fe, we find that single-site rotations, associated with spin temperatures around ∼100 K, induce significant modifications, particularly in Dzyaloshinskii-Moriya-type couplings; in contrast, such interactions in Co and Ni remain almost configuration independent. Moreover, we demonstrate a notable change in the exchange-mediated magnetoelastic constants for Fe under isostatic compression. Finally, the conversion between atomistic, quantum-mechanically derived parameters and the phenomenological magnetoelastic theory is discussed, which can be an useful tool towards larger and more realistic dynamics simulations involving coupled subsystems.},
keywords = {},
pubstate = {published},
tppubtype = {misc}
}

Fechar
Magnetoelasticity plays a crucial role in numerous magnetic phenomena, including magnetocalorics, magnon excitation via acoustic waves, and ultrafast demagnetization/Einstein-de Haas effect. Despite a long-standing discussion on anisotropy-mediated magnetoelastic interactions of relativistic origin, including textit{ab-initio} calculations, the exchange-mediated magnetoelastic parameters within an atomistic framework have only recently begun to be investigated. As a result, many of their behaviors and values for real materials remain poorly understood. Therefore, by using a proposed simple modification of the embedded cluster approach that reduces the computational complexity, we critically analyze the properties of exchange-mediated spin-lattice coupling parameters for elemental 3d ferromagnets (bcc Fe, fcc Ni, and fcc Co), comparing methods used for their extraction and relating their realistic values to symmetry considerations and orbitally-decomposed contributions. Additionally, we investigate the effects of noncollinearity (spin temperature) and applied pressure on these parameters. For Fe, we find that single-site rotations, associated with spin temperatures around ∼100 K, induce significant modifications, particularly in Dzyaloshinskii-Moriya-type couplings; in contrast, such interactions in Co and Ni remain almost configuration independent. Moreover, we demonstrate a notable change in the exchange-mediated magnetoelastic constants for Fe under isostatic compression. Finally, the conversion between atomistic, quantum-mechanically derived parameters and the phenomenological magnetoelastic theory is discussed, which can be an useful tool towards larger and more realistic dynamics simulations involving coupled subsystems.
Fechar
https://arxiv.org/abs/2409.18274
Fechar
14.
Porciúncula, Giuliano G.; Júnior, Marcone I. Sena; Pereira, Luiz Felipe C.; Vilela, André L. M.
Consensus effects of social media synthetic influence groups on scale-free networks Working paper
2024.
Resumo | Links | BibTeX | Tags:
@workingpaper{porciúncula2024consensuseffectssocialmedia,
title = {Consensus effects of social media synthetic influence groups on scale-free networks},
author = {Giuliano G. Porciúncula and Marcone I. Sena Júnior and Luiz Felipe C. Pereira and André L. M. Vilela},
url = {https://arxiv.org/abs/2409.10830},
doi = { https://doi.org/10.48550/arXiv.2409.10830},
year = {2024},
date = {2024-09-17},
urldate = {2024-01-01},
abstract = {Online platforms for social interactions are an essential part of modern society. With the advance of technology and the rise of algorithms and AI, content is now filtered systematically and facilitates the formation of filter bubbles. This work investigates the social consensus under limited visibility in a two-state majority-vote model on Barabási-Albert scale-free networks. In the consensus evolution, each individual assimilates the opinion of the majority of their neighbors with probability 1−q and disagrees with chance q, known as the noise parameter. We define the visibility parameter V as the probability of an individual considering the opinion of a neighbor at a given interaction. The parameter V enables us to model the limited visibility phenomenon that produces synthetic neighborhoods in online interactions. We employ Monte Carlo simulations and finite-size scaling analysis to obtain the critical noise parameter as a function of the visibility V and the growth parameter z. We find the critical exponents β/ν¯, γ/ν¯ and 1/ν¯ of and validate their unitary relation for complex networks. Our analysis shows that installing and manipulating synthetic influence groups critically undermines consensus robustness.},
keywords = {},
pubstate = {published},
tppubtype = {workingpaper}
}

Fechar
Online platforms for social interactions are an essential part of modern society. With the advance of technology and the rise of algorithms and AI, content is now filtered systematically and facilitates the formation of filter bubbles. This work investigates the social consensus under limited visibility in a two-state majority-vote model on Barabási-Albert scale-free networks. In the consensus evolution, each individual assimilates the opinion of the majority of their neighbors with probability 1−q and disagrees with chance q, known as the noise parameter. We define the visibility parameter V as the probability of an individual considering the opinion of a neighbor at a given interaction. The parameter V enables us to model the limited visibility phenomenon that produces synthetic neighborhoods in online interactions. We employ Monte Carlo simulations and finite-size scaling analysis to obtain the critical noise parameter as a function of the visibility V and the growth parameter z. We find the critical exponents β/ν¯, γ/ν¯ and 1/ν¯ of and validate their unitary relation for complex networks. Our analysis shows that installing and manipulating synthetic influence groups critically undermines consensus robustness.
Fechar
https://arxiv.org/abs/2409.10830
doi: https://doi.org/10.48550/arXiv.2409.10830
Fechar
15.
Kegler, Vanessa D.; Oliveira, Igor S. S.; Pacine, Dominike; Nunes, Ricardo W.; Pereira, Teldo A. S.; Lima, Erika Nascimento
Group-IV Pentaoctite: A New 2D Material Family Miscellaneous
2024.
Resumo | Links | BibTeX | Tags:
@misc{kegler2024groupivpentaoctitenew2d,
title = {Group-IV Pentaoctite: A New 2D Material Family},
author = {Vanessa D. Kegler and Igor S. S. Oliveira and Dominike Pacine and Ricardo W. Nunes and Teldo A. S. Pereira and Erika Nascimento Lima},
url = {https://arxiv.org/abs/2409.05986},
year = {2024},
date = {2024-09-11},
urldate = {2024-01-01},
abstract = {This study investigates the structural, mechanical, and electronic properties of novel two-dimensional (2D) pentaoctite (PO) monolayers composed of group-IV elements (PO-C, PO-Si, PO-Ge, and PO-Sn) using first-principles calculations. Stability is explored through phonon spectra and ab initio molecular dynamics simulations, confirming that all proposed structures are dynamically and thermally stable. Mechanical analysis shows that PO-C monolayers exhibit exceptional rigidity, while the others demonstrate greater flexibility, making them suitable for applications in foldable materials. The electronic properties show semimetallic behavior for PO-C and metallic behavior for PO-Si, while PO-Ge and PO-Sn possess narrow band gaps, positioning them as promising candidates for semiconductor applications. Additionally, PO-C exhibits potential as an efficient catalyst for the hydrogen evolution reaction (HER), with strain engineering further enhancing its catalytic performance. These findings suggest a wide range of technological applications, from nanoelectronics and nanomechanics to metal-free catalysis in sustainable energy production.},
keywords = {},
pubstate = {published},
tppubtype = {misc}
}

Fechar
This study investigates the structural, mechanical, and electronic properties of novel two-dimensional (2D) pentaoctite (PO) monolayers composed of group-IV elements (PO-C, PO-Si, PO-Ge, and PO-Sn) using first-principles calculations. Stability is explored through phonon spectra and ab initio molecular dynamics simulations, confirming that all proposed structures are dynamically and thermally stable. Mechanical analysis shows that PO-C monolayers exhibit exceptional rigidity, while the others demonstrate greater flexibility, making them suitable for applications in foldable materials. The electronic properties show semimetallic behavior for PO-C and metallic behavior for PO-Si, while PO-Ge and PO-Sn possess narrow band gaps, positioning them as promising candidates for semiconductor applications. Additionally, PO-C exhibits potential as an efficient catalyst for the hydrogen evolution reaction (HER), with strain engineering further enhancing its catalytic performance. These findings suggest a wide range of technological applications, from nanoelectronics and nanomechanics to metal-free catalysis in sustainable energy production.
Fechar
https://arxiv.org/abs/2409.05986
Fechar
16.
Marques, Mateus; Melo, Bruno M. Souza; Rocha, Alexandre Reily; Lewenkopf, Caio; Silva, Luis G. G. V. Dias
Suppression of the Mott insulating phase in the particle-hole asymmetric Hubbard model Miscellaneous
2024.
Resumo | Links | BibTeX | Tags:
@misc{marques2024suppressionmottinsulatingphase,
title = {Suppression of the Mott insulating phase in the particle-hole asymmetric Hubbard model},
author = {Mateus Marques and Bruno M. Souza Melo and Alexandre Reily Rocha and Caio Lewenkopf and Luis G. G. V. Dias Silva},
url = {https://arxiv.org/abs/2409.06674},
year = {2024},
date = {2024-09-10},
urldate = {2024-01-01},
abstract = {We explore the phase diagram of the Mott metal-insulator transition (MIT), focusing on the effects of particle-hole asymmetry (PHA) in the single-band Hubbard model. Our dynamical mean-field theory (DMFT) study reveals that the introduction of PHA in the model significantly influences the critical temperature (Tc) and interaction strength (Uc), as well as the size of the co-existence region of metallic and insulating phases at low temperatures. Specifically, as the system is moved away from particle-hole symmetry, Tc decreases and Uc increases, indicating a suppression of the insulating phase and the strengthening of the metallic behavior. Additionally, the first-order transition line between metallic and insulating phases is better defined in the model with PHA, leading to a reduced co-existence region at T keywords = {},
pubstate = {published},
tppubtype = {misc}
}

Fechar
We explore the phase diagram of the Mott metal-insulator transition (MIT), focusing on the effects of particle-hole asymmetry (PHA) in the single-band Hubbard model. Our dynamical mean-field theory (DMFT) study reveals that the introduction of PHA in the model significantly influences the critical temperature (Tc) and interaction strength (Uc), as well as the size of the co-existence region of metallic and insulating phases at low temperatures. Specifically, as the system is moved away from particle-hole symmetry, Tc decreases and Uc increases, indicating a suppression of the insulating phase and the strengthening of the metallic behavior. Additionally, the first-order transition line between metallic and insulating phases is better defined in the model with PHA, leading to a reduced co-existence region at T<Tc. Moreover, we propose that the MIT can be characterized by the charge density, which serves as a viable alternative to zero-frequency spectral density typically used in DMFT calculations. Our findings provide new insights into the role of particle-hole asymmetry in the qualitative and quantitative characterization of the MIT even in a very simple system.
Fechar
https://arxiv.org/abs/2409.06674
Fechar
17.
Lemos, Victor Secco; de Moraes, Daniel Angeli; de Lacerda Pataca, Iara; Verruma, Olavo Fiamencini; Torres, Carolina Pirogini; Albuquerque, Angela; Rodríguez-Gutiérrez, Ingrid; Janes, Danilo Biazon; de Lima, F. Crasto; Souza, Flavio Leandro; Leite, Edson Roberto; Fazzio, Adalberto; Junior, João Batista Souza
Platinum Selenide Nanoparticle Synthesis and Reaction with Butyllithium Breaking the Long-Range Ordering Structure Journal Article
Em: Chem. Mater., 2024, ISSN: 1520-5002.
Resumo | Links | BibTeX | Tags:
@article{Lemos2024,
title = {Platinum Selenide Nanoparticle Synthesis and Reaction with Butyllithium Breaking the Long-Range Ordering Structure},
author = {Victor Secco Lemos and Daniel Angeli de Moraes and Iara de Lacerda Pataca and Olavo Fiamencini Verruma and Carolina Pirogini Torres and Angela Albuquerque and Ingrid Rodríguez-Gutiérrez and Danilo Biazon Janes and F. Crasto de Lima and Flavio Leandro Souza and Edson Roberto Leite and Adalberto Fazzio and João Batista Souza Junior},
url = {https://pubs.acs.org/doi/abs/10.1021/acs.chemmater.4c00753},
doi = {10.1021/acs.chemmater.4c00753},
issn = {1520-5002},
year = {2024},
date = {2024-09-10},
urldate = {2024-09-10},
journal = {Chem. Mater.},
publisher = {American Chemical Society (ACS)},
abstract = {PtSe2 is a transition metal dichalcogenide (TMD) material with a broad range of applications, such as sensors, electronics, and catalysis. Although 2D monolayers of PtSe2 have been widely studied, the synthesis of controlled PtSe2 nanoparticles (NPs) is still unexplored. Here, the new strategy to synthesize PtSe2 NPs was to react Pt NPs with selenium in a liquid state inside a homemade closed reactor. Afterward, the PtSe2 NPs reaction with butyllithium led to cleavage of the covalent bond along the ab-plane of 2D material (intralayer) and broke the PtSe2 long-range structure. The result was a PtSex nanomaterial with a greater concentration of defects having only the short-range ordering but keeping the local structure, as proved by Raman and ePDF analyses. X-ray photoelectron spectroscopy revealed a higher contribution from defects (Pt 4f ∼72 eV) for PtSex compared to the crystalline PtSe2 chemical environment (∼73.2 eV), probably due to the creation of edges on the surface of PtSex. PtSe2, and PtSex NPs’ performance toward the hydrogen evolution reaction (HER) application was tested, which indicated a better efficiency than bulk PtSe2. However, the disordered PtSex sample has better electrocatalytic activity, as the number of defects and increased edge exposure create more active sites. Therefore, the results reported here indicate that PtSe2 NPs can be produced using a fast and simple method compared to standard selenization processes, and the activation toward the HER was further enhanced by defect engineering.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

Fechar
PtSe2 is a transition metal dichalcogenide (TMD) material with a broad range of applications, such as sensors, electronics, and catalysis. Although 2D monolayers of PtSe2 have been widely studied, the synthesis of controlled PtSe2 nanoparticles (NPs) is still unexplored. Here, the new strategy to synthesize PtSe2 NPs was to react Pt NPs with selenium in a liquid state inside a homemade closed reactor. Afterward, the PtSe2 NPs reaction with butyllithium led to cleavage of the covalent bond along the ab-plane of 2D material (intralayer) and broke the PtSe2 long-range structure. The result was a PtSex nanomaterial with a greater concentration of defects having only the short-range ordering but keeping the local structure, as proved by Raman and ePDF analyses. X-ray photoelectron spectroscopy revealed a higher contribution from defects (Pt 4f ∼72 eV) for PtSex compared to the crystalline PtSe2 chemical environment (∼73.2 eV), probably due to the creation of edges on the surface of PtSex. PtSe2, and PtSex NPs’ performance toward the hydrogen evolution reaction (HER) application was tested, which indicated a better efficiency than bulk PtSe2. However, the disordered PtSex sample has better electrocatalytic activity, as the number of defects and increased edge exposure create more active sites. Therefore, the results reported here indicate that PtSe2 NPs can be produced using a fast and simple method compared to standard selenization processes, and the activation toward the HER was further enhanced by defect engineering.
Fechar
https://pubs.acs.org/doi/abs/10.1021/acs.chemmater.4c00753
doi:10.1021/acs.chemmater.4c00753
Fechar
18.
Homem-de-Mello, Paula; de Souza, Ana Clara Gonzalez; Melo, Diêgo U.; Mol, Gabriel S.; Souza, Jhonathan R. De; Carneiro, Leonardo M.; Nobrega, Maíra G.; Zanotto, Mateus; Corrêa, Raissa Lohanna G. Q.; de Oliveira, Hueder P. M.; Bartoloni, Fernando H.; Aoto, Yuri A.; Coutinho-Neto, Maurício Domingues; Orestes, Ednilsom
DESIGN BIOINSPIRADO DE CORANTES Journal Article
Em: Quim. Nova, 2024, ISSN: 1678-7064.
Resumo | Links | BibTeX | Tags:
@article{Homem-de-Mello2025,
title = {DESIGN BIOINSPIRADO DE CORANTES},
author = {Paula Homem-de-Mello and Ana Clara Gonzalez de Souza and Diêgo U. Melo and Gabriel S. Mol and Jhonathan R. De Souza and Leonardo M. Carneiro and Maíra G. Nobrega and Mateus Zanotto and Raissa Lohanna G. Q. Corrêa and Hueder P. M. de Oliveira and Fernando H. Bartoloni and Yuri A. Aoto and Maurício Domingues Coutinho-Neto and Ednilsom Orestes},
url = {https://www.scielo.br/j/qn/a/RCr5ZtRt4bVGwZhp5nxGSjP/},
doi = {10.21577/0100-4042.20250047},
issn = {1678-7064},
year = {2024},
date = {2024-09-09},
urldate = {2025-00-00},
journal = {Quim. Nova},
publisher = {Sociedade Brasileira de Quimica (SBQ)},
abstract = {The history of the discovery, use, and development of dyes is closely linked to the history of humanity itself. Among the first records of human civilization are cave paintings made from, e.g., fruits, plants, minerals, and insects. Over the centuries, using different techniques, colors have been given to all types of materials and products, from clothing to food. The chemicals responsible for colors are dyes - a vast collection of molecules of the most varied compositions, but which have in common the absorption of light within the visible window of the electromagnetic spectrum. This article aims not only to review the properties of some classes of natural dyes, their origins, and their applications but also to describe the various computational chemistry methods involved in designing new bio-inspired molecules.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

Fechar
The history of the discovery, use, and development of dyes is closely linked to the history of humanity itself. Among the first records of human civilization are cave paintings made from, e.g., fruits, plants, minerals, and insects. Over the centuries, using different techniques, colors have been given to all types of materials and products, from clothing to food. The chemicals responsible for colors are dyes – a vast collection of molecules of the most varied compositions, but which have in common the absorption of light within the visible window of the electromagnetic spectrum. This article aims not only to review the properties of some classes of natural dyes, their origins, and their applications but also to describe the various computational chemistry methods involved in designing new bio-inspired molecules.
Fechar
https://www.scielo.br/j/qn/a/RCr5ZtRt4bVGwZhp5nxGSjP/
doi:10.21577/0100-4042.20250047
Fechar
19.
Quispe, Juan Gomez; Ipaves, Bruno; Galvao, Douglas Soares; Autreto, Pedro A. S.
TPDH-Graphene as a New Anodic Material for Lithium Ion Battery: DFT-Based Investigations Journal Article
Em: ACS Omega, 2024, ISSN: 2470-1343.
Resumo | Links | BibTeX | Tags:
@article{GomezQuispe2024,
title = {TPDH-Graphene as a New Anodic Material for Lithium Ion Battery: DFT-Based Investigations},
author = {Juan Gomez Quispe and Bruno Ipaves and Douglas Soares Galvao and Pedro A. S. Autreto},
url = {https://pubs.acs.org/doi/10.1021/acsomega.4c06252},
doi = {10.1021/acsomega.4c06252},
issn = {2470-1343},
year = {2024},
date = {2024-09-03},
urldate = {2024-09-03},
journal = {ACS Omega},
publisher = {American Chemical Society (ACS)},
abstract = {The potential of tetra-penta-deca-hexagonal graphene (TPDH-gr), a recently proposed 2D carbon allotrope as an anodic material in lithium ion batteries (LIBs), was investigated through density functional theory calculations. The results indicate that Li-atom adsorption is moderate (around 0.70 eV), allowing for easy desorption. Moreover, energy barriers (0.08–0.20 eV), diffusion coefficient (>6 × 10–6 cm2/s), and open circuit voltage (0.29 V) calculations show rapid Li atom diffusion on the TPDH-gr surface, stable intercalation of lithium atoms, and good performance during the charge and discharge cycles of the LIB. These findings, combined with the intrinsic metallic nature of TPDH-gr, indicate that this new 2D carbon allotrope is a promising candidate for use as an anodic LIB material.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

Fechar
The potential of tetra-penta-deca-hexagonal graphene (TPDH-gr), a recently proposed 2D carbon allotrope as an anodic material in lithium ion batteries (LIBs), was investigated through density functional theory calculations. The results indicate that Li-atom adsorption is moderate (around 0.70 eV), allowing for easy desorption. Moreover, energy barriers (0.08–0.20 eV), diffusion coefficient (>6 × 10–6 cm2/s), and open circuit voltage (0.29 V) calculations show rapid Li atom diffusion on the TPDH-gr surface, stable intercalation of lithium atoms, and good performance during the charge and discharge cycles of the LIB. These findings, combined with the intrinsic metallic nature of TPDH-gr, indicate that this new 2D carbon allotrope is a promising candidate for use as an anodic LIB material.
Fechar
https://pubs.acs.org/doi/10.1021/acsomega.4c06252
doi:10.1021/acsomega.4c06252
Fechar
20.
Araújo, Augusto L.; de Lima, F. Crasto; Fazzio, Adalberto
Reentrant topological phase in half-Heusler compounds Miscellaneous
2024.
Resumo | Links | BibTeX | Tags:
@misc{araújo2024reentranttopologicalphasehalfheusler,
title = {Reentrant topological phase in half-Heusler compounds},
author = {Augusto L. Araújo and F. Crasto de Lima and Adalberto Fazzio},
url = {https://arxiv.org/abs/2409.01385},
year = {2024},
date = {2024-09-02},
urldate = {2024-01-01},
abstract = {Half-Heusler compounds are known for their various compositions and multifunctional properties including topological phases. In this study, we investigate the topological classification of this class of materials based on the ordering of the Γ6, Γ8 states, and a previously overlooked Γ∗6 state, during an adiabatic expansion process. Using first-principles calculations based on density functional theory, we observed that the non-trivial topology is governed by a three-band mechanism. We provide a simple model derived from k⋅p Hamiltonian that interprets the topological phase in half-Heusler systems. Additionally, we explore the robustness of the topological phase under tension and a new perspective on the topological nature of half-Heusler compounds.},
keywords = {},
pubstate = {published},
tppubtype = {misc}
}

Fechar
Half-Heusler compounds are known for their various compositions and multifunctional properties including topological phases. In this study, we investigate the topological classification of this class of materials based on the ordering of the Γ6, Γ8 states, and a previously overlooked Γ∗6 state, during an adiabatic expansion process. Using first-principles calculations based on density functional theory, we observed that the non-trivial topology is governed by a three-band mechanism. We provide a simple model derived from k⋅p Hamiltonian that interprets the topological phase in half-Heusler systems. Additionally, we explore the robustness of the topological phase under tension and a new perspective on the topological nature of half-Heusler compounds.
Fechar
https://arxiv.org/abs/2409.01385
Fechar
237 entradas « ‹ 1 de 12 › »