Antonio Castro Neto
Degree: PhD
Position: Director, Centre for Advanced 2D Materials
Research Type: Theory
Office: S14-06-13
Email: c2dhead@nus.edu.sg
Contact: (65) 6601 2575
CA2DM Publications:
2023 |
Whitcher, T J; Fauzi, A D; Diao, C; Chi, X; Syahroni, A; Asmara, T C; Breese, M B H; Neto, Castro A H; Wee, A T S; Majidi, M A; Rusydi, A Reply to: Reassessing the existence of soft X-ray correlated plasmons Journal Article NATURE COMMUNICATIONS, 14 (1), 2023. @article{ISI:001089230100018, title = {Reply to: Reassessing the existence of soft X-ray correlated plasmons}, author = {T J Whitcher and A D Fauzi and C Diao and X Chi and A Syahroni and T C Asmara and M B H Breese and Castro A H Neto and A T S Wee and M A Majidi and A Rusydi}, doi = {10.1038/s41467-023-40652-9}, times_cited = {0}, year = {2023}, date = {2023-10-24}, journal = {NATURE COMMUNICATIONS}, volume = {14}, number = {1}, publisher = {NATURE PORTFOLIO}, address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Fang, Hanyan; Mahalingam, Harshitra; Li, Xinzhe; Han, Xu; Qiu, Zhizhan; Han, Yixuan; Noori, Keian; Dulal, Dikshant; Chen, Hongfei; Lyu, Pin; Yang, Tianhao; Li, Jing; Su, Chenliang; Chen, Wei; Cai, Yongqing; Neto, Castro A H; Novoselov, Kostya S; Rodin, Aleksandr; Lu, Jiong Atomically precise vacancy-assembled quantum antidots Journal Article NATURE NANOTECHNOLOGY, 18 (12), 2023, ISSN: 1748-3387. @article{ISI:001062548200002, title = {Atomically precise vacancy-assembled quantum antidots}, author = {Hanyan Fang and Harshitra Mahalingam and Xinzhe Li and Xu Han and Zhizhan Qiu and Yixuan Han and Keian Noori and Dikshant Dulal and Hongfei Chen and Pin Lyu and Tianhao Yang and Jing Li and Chenliang Su and Wei Chen and Yongqing Cai and Castro A H Neto and Kostya S Novoselov and Aleksandr Rodin and Jiong Lu}, doi = {10.1038/s41565-023-01495-z}, times_cited = {0}, issn = {1748-3387}, year = {2023}, date = {2023-08-31}, journal = {NATURE NANOTECHNOLOGY}, volume = {18}, number = {12}, publisher = {NATURE PORTFOLIO}, address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY}, abstract = {Patterning antidots, which are regions of potential hills that repel electrons, into well-defined antidot lattices creates fascinating artificial periodic structures, leading to anomalous transport properties and exotic quantum phenomena in two-dimensional systems. Although nanolithography has brought conventional antidots from the semiclassical regime to the quantum regime, achieving precise control over the size of each antidot and its spatial period at the atomic scale has remained challenging. However, attaining such control opens the door to a new paradigm, enabling the creation of quantum antidots with discrete quantum hole states, which, in turn, offer a fertile platform to explore novel quantum phenomena and hot electron dynamics in previously inaccessible regimes. Here we report an atomically precise bottom-up fabrication of a series of atomic-scale quantum antidots through a thermal-induced assembly of a chalcogenide single vacancy in PtTe2. Such quantum antidots consist of highly ordered single-vacancy lattices, spaced by a single Te atom, reaching the ultimate downscaling limit of antidot lattices. Increasing the number of single vacancies in quantum antidots strengthens the cumulative repulsive potential and consequently enhances the collective interference of multiple-pocket scattered quasiparticles inside quantum antidots, creating multilevel quantum hole states with a tunable gap from the telecom to far-infrared regime. Moreover, precisely engineered quantum hole states of quantum antidots are geometry protected and thus survive on oxygen substitutional doping. Therefore, single-vacancy-assembled quantum antidots exhibit unprecedented robustness and property tunability, positioning them as highly promising candidates for advancing quantum information and photocatalysis technologies.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Patterning antidots, which are regions of potential hills that repel electrons, into well-defined antidot lattices creates fascinating artificial periodic structures, leading to anomalous transport properties and exotic quantum phenomena in two-dimensional systems. Although nanolithography has brought conventional antidots from the semiclassical regime to the quantum regime, achieving precise control over the size of each antidot and its spatial period at the atomic scale has remained challenging. However, attaining such control opens the door to a new paradigm, enabling the creation of quantum antidots with discrete quantum hole states, which, in turn, offer a fertile platform to explore novel quantum phenomena and hot electron dynamics in previously inaccessible regimes. Here we report an atomically precise bottom-up fabrication of a series of atomic-scale quantum antidots through a thermal-induced assembly of a chalcogenide single vacancy in PtTe2. Such quantum antidots consist of highly ordered single-vacancy lattices, spaced by a single Te atom, reaching the ultimate downscaling limit of antidot lattices. Increasing the number of single vacancies in quantum antidots strengthens the cumulative repulsive potential and consequently enhances the collective interference of multiple-pocket scattered quasiparticles inside quantum antidots, creating multilevel quantum hole states with a tunable gap from the telecom to far-infrared regime. Moreover, precisely engineered quantum hole states of quantum antidots are geometry protected and thus survive on oxygen substitutional doping. Therefore, single-vacancy-assembled quantum antidots exhibit unprecedented robustness and property tunability, positioning them as highly promising candidates for advancing quantum information and photocatalysis technologies. |
Trushin, Maxim; Carvalho, Alexandra; Neto, Castro A H Two-dimensional non-linear hydrodynamics and nanofluidics Journal Article COMMUNICATIONS PHYSICS, 6 (1), 2023, ISSN: 2399-3650. @article{ISI:001021478100002, title = {Two-dimensional non-linear hydrodynamics and nanofluidics}, author = {Maxim Trushin and Alexandra Carvalho and Castro A H Neto}, doi = {10.1038/s42005-023-01274-1}, times_cited = {0}, issn = {2399-3650}, year = {2023}, date = {2023-07-03}, journal = {COMMUNICATIONS PHYSICS}, volume = {6}, number = {1}, publisher = {NATURE PORTFOLIO}, address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY}, abstract = {A water monolayer squeezed between two solid planes experiences strong out-of-plane confinement effects while expanding freely within the plane. As a consequence, the transport of such two-dimensional water combines hydrodynamic and nanofluidic features, intimately linked with each other. In this paper, we propose and explicitly solve a non-linear hydrodynamic equation describing two-dimensional water flow with viscosity parameters deduced from molecular dynamic simulations. We demonstrate that the very ability of two-dimensional water to flow in short channels is governed by the second (dilatational) viscosity coefficient, leading to flow compression and velocity saturation in the high-pressure limit. The viscosity parameter values depend strongly on whether graphene or hexoganal boron nitride layers are used to confine 2D water that offers an interesting opportunity to obtain various nanofluids out of the same water molecules just by using alternate materials to fabricate the 2D channels.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A water monolayer squeezed between two solid planes experiences strong out-of-plane confinement effects while expanding freely within the plane. As a consequence, the transport of such two-dimensional water combines hydrodynamic and nanofluidic features, intimately linked with each other. In this paper, we propose and explicitly solve a non-linear hydrodynamic equation describing two-dimensional water flow with viscosity parameters deduced from molecular dynamic simulations. We demonstrate that the very ability of two-dimensional water to flow in short channels is governed by the second (dilatational) viscosity coefficient, leading to flow compression and velocity saturation in the high-pressure limit. The viscosity parameter values depend strongly on whether graphene or hexoganal boron nitride layers are used to confine 2D water that offers an interesting opportunity to obtain various nanofluids out of the same water molecules just by using alternate materials to fabricate the 2D channels. |
Kazeev, Nikita; Al-Maeeni, Abdalaziz Rashid; Romanov, Ignat; Faleev, Maxim; Lukin, Ruslan; Tormasov, Alexander; Neto, Castro A H; Novoselov, Kostya S; Huang, Pengru; Ustyuzhanin, Andrey Sparse representation for machine learning the properties of defects in 2D materials Journal Article NPJ COMPUTATIONAL MATERIALS, 9 (1), 2023. @article{ISI:001016773900002, title = {Sparse representation for machine learning the properties of defects in 2D materials}, author = {Nikita Kazeev and Abdalaziz Rashid Al-Maeeni and Ignat Romanov and Maxim Faleev and Ruslan Lukin and Alexander Tormasov and Castro A H Neto and Kostya S Novoselov and Pengru Huang and Andrey Ustyuzhanin}, doi = {10.1038/s41524-023-01062-z}, times_cited = {0}, year = {2023}, date = {2023-06-26}, journal = {NPJ COMPUTATIONAL MATERIALS}, volume = {9}, number = {1}, publisher = {NATURE PORTFOLIO}, address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY}, abstract = {Two-dimensional materials offer a promising platform for the next generation of (opto-) electronic devices and other high technology applications. One of the most exciting characteristics of 2D crystals is the ability to tune their properties via controllable introduction of defects. However, the search space for such structures is enormous, and ab-initio computations prohibitively expensive. We propose a machine learning approach for rapid estimation of the properties of 2D material given the lattice structure and defect configuration. The method suggests a way to represent configuration of 2D materials with defects that allows a neural network to train quickly and accurately. We compare our methodology with the state-of-the-art approaches and demonstrate at least 3.7 times energy prediction error drop. Also, our approach is an order of magnitude more resource-efficient than its contenders both for the training and inference part.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Two-dimensional materials offer a promising platform for the next generation of (opto-) electronic devices and other high technology applications. One of the most exciting characteristics of 2D crystals is the ability to tune their properties via controllable introduction of defects. However, the search space for such structures is enormous, and ab-initio computations prohibitively expensive. We propose a machine learning approach for rapid estimation of the properties of 2D material given the lattice structure and defect configuration. The method suggests a way to represent configuration of 2D materials with defects that allows a neural network to train quickly and accurately. We compare our methodology with the state-of-the-art approaches and demonstrate at least 3.7 times energy prediction error drop. Also, our approach is an order of magnitude more resource-efficient than its contenders both for the training and inference part. |
Carrio, Juan A G; Talluri, Prasad V S S L; Toolahalli, Swamy T; Echeverrigaray, Sergio G; Neto, Castro A H Gas stripping assisted vapour permeation using graphene membrane on silicon carbide for ethanol recovery Journal Article SCIENTIFIC REPORTS, 13 (1), 2023, ISSN: 2045-2322. @article{ISI:001044376300069, title = {Gas stripping assisted vapour permeation using graphene membrane on silicon carbide for ethanol recovery}, author = {Juan A G Carrio and Prasad V S S L Talluri and Swamy T Toolahalli and Sergio G Echeverrigaray and Castro A H Neto}, doi = {10.1038/s41598-023-37080-6}, times_cited = {0}, issn = {2045-2322}, year = {2023}, date = {2023-06-16}, journal = {SCIENTIFIC REPORTS}, volume = {13}, number = {1}, publisher = {NATURE PORTFOLIO}, address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY}, abstract = {The conventional methods for ethanol recovery in low concentrations from diluted aqueous solutions are limited by the high energy consumed. Therefore, developing a cost-effective advanced membrane process for ethanol recovery and concentration is still necessary. A gas stripping-assisted vapour permeation (GSVP) process was applied to concentrate ethanol by the selective removal of water using hydrophilic graphene oxide (GO) membranes. Silicon carbide porous tubes were internally coated with GO-based membranes with an average thickness of 1.1 mu m as a selective layer. Dry N-2 was bubbled into the feed solution, carrying the saturated vapours to the separation module. The modified GSVP process was implemented to recover ethanol at lower temperatures than direct distillation and close-ended GSVP processes. The performance of the membrane-coated tubes was evaluated as a function of temperature and feed concentration, ranging from 23 to 60 degrees C and 10 wt% to 50 wt%. Distillates with 67 wt% and 87 wt% were obtained from feeds with 10 and 50 wt% ethanol at 50 degrees C, respectively. The evaporation energy spent by the modified GSVP process using GO-coated SiC tubes was 22% and 31% lower than the traditional distillation and vapour stripping processes.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The conventional methods for ethanol recovery in low concentrations from diluted aqueous solutions are limited by the high energy consumed. Therefore, developing a cost-effective advanced membrane process for ethanol recovery and concentration is still necessary. A gas stripping-assisted vapour permeation (GSVP) process was applied to concentrate ethanol by the selective removal of water using hydrophilic graphene oxide (GO) membranes. Silicon carbide porous tubes were internally coated with GO-based membranes with an average thickness of 1.1 mu m as a selective layer. Dry N-2 was bubbled into the feed solution, carrying the saturated vapours to the separation module. The modified GSVP process was implemented to recover ethanol at lower temperatures than direct distillation and close-ended GSVP processes. The performance of the membrane-coated tubes was evaluated as a function of temperature and feed concentration, ranging from 23 to 60 degrees C and 10 wt% to 50 wt%. Distillates with 67 wt% and 87 wt% were obtained from feeds with 10 and 50 wt% ethanol at 50 degrees C, respectively. The evaporation energy spent by the modified GSVP process using GO-coated SiC tubes was 22% and 31% lower than the traditional distillation and vapour stripping processes. |
Huang, Pengru; Lukin, Ruslan; Faleev, Maxim; Kazeev, Nikita; Al-Maeeni, Abdalaziz Rashid; Andreeva, Daria V; Ustyuzhanin, Andrey; Tormasov, Alexander; Neto, Castro A H; Novoselov, Kostya S Unveiling the complex structure-property correlation of defects in 2D materials based on high throughput datasets (vol 7, 6, 2023) Journal Article NPJ 2D MATERIALS AND APPLICATIONS, 7 (1), 2023. @article{ISI:000980421600001, title = {Unveiling the complex structure-property correlation of defects in 2D materials based on high throughput datasets (vol 7, 6, 2023)}, author = {Pengru Huang and Ruslan Lukin and Maxim Faleev and Nikita Kazeev and Abdalaziz Rashid Al-Maeeni and Daria V Andreeva and Andrey Ustyuzhanin and Alexander Tormasov and Castro A H Neto and Kostya S Novoselov}, doi = {10.1038/s41699-023-00397-x}, times_cited = {0}, year = {2023}, date = {2023-04-28}, journal = {NPJ 2D MATERIALS AND APPLICATIONS}, volume = {7}, number = {1}, publisher = {NATURE PORTFOLIO}, address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Donato, Katarzyna Z; Tan, Hui Li; Marangoni, Valeria S; Martins, Marcos V S; Ng, Pei Rou; Costa, Mariana C F; Jain, Purvi; Lee, Sarah J; Koon, Gavin K W; Donato, Ricardo K; Neto, Castro A H Graphene oxide classification and standardization Journal Article SCIENTIFIC REPORTS, 13 (1), 2023, ISSN: 2045-2322. @article{ISI:000984454500063, title = {Graphene oxide classification and standardization}, author = {Katarzyna Z Donato and Hui Li Tan and Valeria S Marangoni and Marcos V S Martins and Pei Rou Ng and Mariana C F Costa and Purvi Jain and Sarah J Lee and Gavin K W Koon and Ricardo K Donato and Castro A H Neto}, doi = {10.1038/s41598-023-33350-5}, times_cited = {0}, issn = {2045-2322}, year = {2023}, date = {2023-04-13}, journal = {SCIENTIFIC REPORTS}, volume = {13}, number = {1}, publisher = {NATURE PORTFOLIO}, address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY}, abstract = {There is a need to classify and standardize graphene-related materials giving the growing use of this materials industrially. One of the most used and more difficult to classify is graphene oxide (GO). Inconsistent definitions of GO, closely relating it to graphene, are found in the literature and industrial brochures. Hence, although they have very different physicochemical properties and industrial applications, commonly used classifications of graphene and GO definitions are not substantial. Consequently, the lack of regulation and standardization create trust issues among sellers and buyers that impede industrial development and progress. With that in mind, this study offers a critical assessment of 34 commercially available GOs, characterized using a systematic and reliable protocol for accessing their quality. We establish correlations between GO physicochemical properties and its applications leading to rationale for its classification.}, keywords = {}, pubstate = {published}, tppubtype = {article} } There is a need to classify and standardize graphene-related materials giving the growing use of this materials industrially. One of the most used and more difficult to classify is graphene oxide (GO). Inconsistent definitions of GO, closely relating it to graphene, are found in the literature and industrial brochures. Hence, although they have very different physicochemical properties and industrial applications, commonly used classifications of graphene and GO definitions are not substantial. Consequently, the lack of regulation and standardization create trust issues among sellers and buyers that impede industrial development and progress. With that in mind, this study offers a critical assessment of 34 commercially available GOs, characterized using a systematic and reliable protocol for accessing their quality. We establish correlations between GO physicochemical properties and its applications leading to rationale for its classification. |
Huang, Pengru; Lukin, Ruslan; Faleev, Maxim; Kazeev, Nikita; Al-Maeeni, Abdalaziz Rashid; Andreeva, Daria V; Ustyuzhanin, Andrey; Tormasov, Alexander; Neto, Castro A H; Novoselov, Kostya S Unveiling the complex structure-property correlation of defects in 2D materials based on high throughput datasets Journal Article NPJ 2D MATERIALS AND APPLICATIONS, 7 (1), 2023. @article{ISI:000924124300002, title = {Unveiling the complex structure-property correlation of defects in 2D materials based on high throughput datasets}, author = {Pengru Huang and Ruslan Lukin and Maxim Faleev and Nikita Kazeev and Abdalaziz Rashid Al-Maeeni and Daria V Andreeva and Andrey Ustyuzhanin and Alexander Tormasov and Castro A H Neto and Kostya S Novoselov}, doi = {10.1038/s41699-023-00369-1}, times_cited = {0}, year = {2023}, date = {2023-02-01}, journal = {NPJ 2D MATERIALS AND APPLICATIONS}, volume = {7}, number = {1}, publisher = {NATURE PORTFOLIO}, address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY}, abstract = {Modification of physical properties of materials and design of materials with on-demand characteristics is at the heart of modern technology. Rare application relies on pure materials-most devices and technologies require careful design of materials properties through alloying, creating heterostructures of composites, or controllable introduction of defects. At the same time, such designer materials are notoriously difficult to model. Thus, it is very tempting to apply machine learning methods to such systems. Unfortunately, there is only a handful of machine learning-friendly material databases available these days. We develop a platform for easy implementation of machine learning techniques to materials design and populate it with datasets on pristine and defected materials. Here we introduce the 2D Material Defect (2DMD) datasets that include defect properties of represented 2D materials such as MoS2, WSe2, hBN, GaSe, InSe, and black phosphorous, calculated using DFT. Our study provides a data-driven physical understanding of complex behaviors of defect properties in 2D materials, holding promise for a guide to the development of efficient machine learning models. In addition, with the increasing enrollment of datasets, our database could provide a platform for designing materials with predetermined properties.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Modification of physical properties of materials and design of materials with on-demand characteristics is at the heart of modern technology. Rare application relies on pure materials-most devices and technologies require careful design of materials properties through alloying, creating heterostructures of composites, or controllable introduction of defects. At the same time, such designer materials are notoriously difficult to model. Thus, it is very tempting to apply machine learning methods to such systems. Unfortunately, there is only a handful of machine learning-friendly material databases available these days. We develop a platform for easy implementation of machine learning techniques to materials design and populate it with datasets on pristine and defected materials. Here we introduce the 2D Material Defect (2DMD) datasets that include defect properties of represented 2D materials such as MoS2, WSe2, hBN, GaSe, InSe, and black phosphorous, calculated using DFT. Our study provides a data-driven physical understanding of complex behaviors of defect properties in 2D materials, holding promise for a guide to the development of efficient machine learning models. In addition, with the increasing enrollment of datasets, our database could provide a platform for designing materials with predetermined properties. |
2022 |
Tan, H L; Ng, P R; Trushin, M; Koon, G K W; Donato, K Z; Costa, M C F; Donato, R K; Neto, Castro A H Self-assembly of 2D-electrolytes into heterostructured nanofibers Journal Article MATERIALS TODAY CHEMISTRY, 27 , 2022, ISSN: 2468-5194. @article{ISI:000976255000001, title = {Self-assembly of 2D-electrolytes into heterostructured nanofibers}, author = {H L Tan and P R Ng and M Trushin and G K W Koon and K Z Donato and M C F Costa and R K Donato and Castro A H Neto}, doi = {10.1016/j.mtchem.2022.101296}, times_cited = {0}, issn = {2468-5194}, year = {2022}, date = {2022-12-06}, journal = {MATERIALS TODAY CHEMISTRY}, volume = {27}, publisher = {ELSEVIER SCI LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {2D materials can be functionalised with various ionisable functional groups of different formal charges, forming the so-called 2D electrolytes. In this study, 2D electrolytes based on functionalised graphene oxide (GO) with cationic groups (-NH3 thorn ) and molybdenum disulfide (MoS2) with anionic groups (-COO-) were used to form heterostructures through a self-assembly process. Due to the presence of opposite charges, heterostructures were formed by the predominantly attractive forces between the 2D electro-lytes in a fluidic aqueous environment. With the application of sonication, both 2D materials were able to overcome the energy barrier offered by their bending stiffness, continuously assembling and scrolling into heterostructured nanofibers. The nanofibers were the product of the conjugated 2D electrolytes, which led to their phase separation and precipitation into highly ordered and high aspect ratio 1D structures. As the reaction proceeds, long nanofiber bundles with branches were formed, resembling the structures formed by naturally occurring polyelectrolytes such as amino acids forming proteins. This method offers a facile approach for the continuous processing of heterostructured nanofibers with a low production cost under flow that can be widely applied in textiles, encapsulation technologies, and nanosensors.(c) 2022 Elsevier Ltd. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } 2D materials can be functionalised with various ionisable functional groups of different formal charges, forming the so-called 2D electrolytes. In this study, 2D electrolytes based on functionalised graphene oxide (GO) with cationic groups (-NH3 thorn ) and molybdenum disulfide (MoS2) with anionic groups (-COO-) were used to form heterostructures through a self-assembly process. Due to the presence of opposite charges, heterostructures were formed by the predominantly attractive forces between the 2D electro-lytes in a fluidic aqueous environment. With the application of sonication, both 2D materials were able to overcome the energy barrier offered by their bending stiffness, continuously assembling and scrolling into heterostructured nanofibers. The nanofibers were the product of the conjugated 2D electrolytes, which led to their phase separation and precipitation into highly ordered and high aspect ratio 1D structures. As the reaction proceeds, long nanofiber bundles with branches were formed, resembling the structures formed by naturally occurring polyelectrolytes such as amino acids forming proteins. This method offers a facile approach for the continuous processing of heterostructured nanofibers with a low production cost under flow that can be widely applied in textiles, encapsulation technologies, and nanosensors.(c) 2022 Elsevier Ltd. All rights reserved. |
Negi, Suchit; Carvalho, Alexandra; Trushin, Maxim; Neto, Castro A H Edge-Driven Phase Transitions in 2D Ice Journal Article JOURNAL OF PHYSICAL CHEMISTRY C, 126 (37), pp. 16006-16015, 2022, ISSN: 1932-7447. @article{ISI:000859271000001, title = {Edge-Driven Phase Transitions in 2D Ice}, author = {Suchit Negi and Alexandra Carvalho and Maxim Trushin and Castro A H Neto}, doi = {10.1021/acs.jpcc.2c04492}, times_cited = {0}, issn = {1932-7447}, year = {2022}, date = {2022-09-13}, journal = {JOURNAL OF PHYSICAL CHEMISTRY C}, volume = {126}, number = {37}, pages = {16006-16015}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {Two-dimensional (2D) water, confined by atomically flat layered materials, may transit into various crystalline phases even at room temperature. However, to gain full control over the crystalline state, we should not only confine water in the out-of-plane direction but also restrict its in-plane motion, forming 2D water clusters or ribbons. One way to do this is by using an electric field, in particular the intrinsic electric field of an adjacent polar material. We have found that the crystalline phases of 2D water clusters placed between two hexagonal boron nitride (h-BN) nanoribbons are crucially determined by the nanoribbons' edges, the resulting polarity of the nanoribbons, and their interlayer distance. We make use of the density functional theory with further assistance of molecular dynamics simulations to establish the comprehensive phase diagrams, demonstrating transitions between liquid and solid phases and between the states of different crystalline orders. We also show that the crystalline orders are maintained when water flows between h-BN channels under external pressure. Our results open a promising pathway toward the control of the water structure and its flow by the use of the microscopic electric field of polar materials.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Two-dimensional (2D) water, confined by atomically flat layered materials, may transit into various crystalline phases even at room temperature. However, to gain full control over the crystalline state, we should not only confine water in the out-of-plane direction but also restrict its in-plane motion, forming 2D water clusters or ribbons. One way to do this is by using an electric field, in particular the intrinsic electric field of an adjacent polar material. We have found that the crystalline phases of 2D water clusters placed between two hexagonal boron nitride (h-BN) nanoribbons are crucially determined by the nanoribbons' edges, the resulting polarity of the nanoribbons, and their interlayer distance. We make use of the density functional theory with further assistance of molecular dynamics simulations to establish the comprehensive phase diagrams, demonstrating transitions between liquid and solid phases and between the states of different crystalline orders. We also show that the crystalline orders are maintained when water flows between h-BN channels under external pressure. Our results open a promising pathway toward the control of the water structure and its flow by the use of the microscopic electric field of polar materials. |
Malhotra, Ritika; Halbig, Christian Eberhard; Sim, Yu Fan; Lim, Chwee Teck; Leong, David Tai; Neto, Castro A H; Garaj, Slaven; Rosa, Vinicius Cytotoxicity survey of commercial graphene materials from worldwide Journal Article NPJ 2D MATERIALS AND APPLICATIONS, 6 (1), 2022. @article{ISI:000852419000001, title = {Cytotoxicity survey of commercial graphene materials from worldwide}, author = {Ritika Malhotra and Christian Eberhard Halbig and Yu Fan Sim and Chwee Teck Lim and David Tai Leong and Castro A H Neto and Slaven Garaj and Vinicius Rosa}, doi = {10.1038/s41699-022-00330-8}, times_cited = {3}, year = {2022}, date = {2022-09-09}, journal = {NPJ 2D MATERIALS AND APPLICATIONS}, volume = {6}, number = {1}, publisher = {NATURE PORTFOLIO}, address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY}, abstract = {Graphene and other 2D materials are having a profound impact on science and technology. Unfortunately, progress in this area has not been followed by strict quality controls and toxicity benchmarks. Herein, we report a survey of the cytotoxicity of 36 products nominally labeled as "graphene." These are available from suppliers worldwide and synthesized through various techniques. Detailed characterization suggests that these products represent a heterogeneous class of materials with varying physicochemical properties and a noticeable quantity of contaminants. We demonstrate that the cellular toxicity of these products is not related to a particular characteristic of graphene; rather, it is fundamentally determined by the presence of impurities in the commercially available graphene family materials tested.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Graphene and other 2D materials are having a profound impact on science and technology. Unfortunately, progress in this area has not been followed by strict quality controls and toxicity benchmarks. Herein, we report a survey of the cytotoxicity of 36 products nominally labeled as "graphene." These are available from suppliers worldwide and synthesized through various techniques. Detailed characterization suggests that these products represent a heterogeneous class of materials with varying physicochemical properties and a noticeable quantity of contaminants. We demonstrate that the cellular toxicity of these products is not related to a particular characteristic of graphene; rather, it is fundamentally determined by the presence of impurities in the commercially available graphene family materials tested. |
Rodin, Aleksandr; Noori, Keian; Carvalho, Alexandra; Neto, Castro A H Microscopic theory of ionic motion in solids Journal Article PHYSICAL REVIEW B, 105 (22), 2022, ISSN: 2469-9950. @article{ISI:000823042500003, title = {Microscopic theory of ionic motion in solids}, author = {Aleksandr Rodin and Keian Noori and Alexandra Carvalho and Castro A H Neto}, doi = {10.1103/PhysRevB.105.224310}, times_cited = {0}, issn = {2469-9950}, year = {2022}, date = {2022-06-21}, journal = {PHYSICAL REVIEW B}, volume = {105}, number = {22}, publisher = {AMER PHYSICAL SOC}, address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, abstract = {Drag and diffusion of mobile ions in solids are of interest for both purely theoretical and applied scientific communities. This article proposes a theoretical description of ion drag in solids that can be used to estimate ionic conductivities in crystals, and forms a basis for the rational design of solid electrolyte materials. Starting with a general solid-state Hamiltonian, we employ the nonequilibrium path integral formalism to develop a microscopic theory of ionic transport in solids in the presence of thermal fluctuations. As required by the fluctuation-dissipation theorem, we obtain a relation between the variance of the random force and friction. Because of the crystalline nature of the system, however, the two quantities are tensorial. We use the drag tensor to write down the formula for ionic mobility, determined by the potential profile generated by the crystal???s ions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Drag and diffusion of mobile ions in solids are of interest for both purely theoretical and applied scientific communities. This article proposes a theoretical description of ion drag in solids that can be used to estimate ionic conductivities in crystals, and forms a basis for the rational design of solid electrolyte materials. Starting with a general solid-state Hamiltonian, we employ the nonequilibrium path integral formalism to develop a microscopic theory of ionic transport in solids in the presence of thermal fluctuations. As required by the fluctuation-dissipation theorem, we obtain a relation between the variance of the random force and friction. Because of the crystalline nature of the system, however, the two quantities are tensorial. We use the drag tensor to write down the formula for ionic mobility, determined by the potential profile generated by the crystal???s ions. |
2021 |
Whitcher, T J; Fauzi, Angga Dito; Caozheng, D; Chi, X; Syahroni, A; Asmara, T C; Breese, M B H; Neto, Castro A H; Wee, A T S; Majidi, Aziz M; Rusydi, A Unravelling strong electronic interlayer and intralayer correlations in a transition metal dichalcogenide Journal Article NATURE COMMUNICATIONS, 12 (1), 2021. @article{ISI:000724450600002, title = {Unravelling strong electronic interlayer and intralayer correlations in a transition metal dichalcogenide}, author = {T J Whitcher and Angga Dito Fauzi and D Caozheng and X Chi and A Syahroni and T C Asmara and M B H Breese and Castro A H Neto and A T S Wee and Aziz M Majidi and A Rusydi}, doi = {10.1038/s41467-021-27182-y}, times_cited = {0}, year = {2021}, date = {2021-11-30}, journal = {NATURE COMMUNICATIONS}, volume = {12}, number = {1}, publisher = {NATURE PORTFOLIO}, address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY}, abstract = {Electronic correlations play important roles in driving exotic phenomena in condensed matter physics. They determine low-energy properties through high-energy bands well-beyond optics. Great effort has been made to understand low-energy excitations such as low-energy excitons in transition metal dichalcogenides (TMDCs), however their high-energy bands and interlayer correlation remain mysteries. Herewith, by measuring temperature- and polarization-dependent complex dielectric and loss functions of bulk molybdenum disulphide from near-infrared to soft X-ray, supported with theoretical calculations, we discover unconventional soft X-ray correlated-plasmons with low-loss, and electronic transitions that reduce dimensionality and increase correlations, accompanied with significantly modified low-energy excitons. At room temperature, interlayer electronic correlations, together with the intralayer correlations in the c-axis, are surprisingly strong, yielding a three-dimensional-like system. Upon cooling, wide-range spectral-weight transfer occurs across a few tens of eV and in-plane p-d hybridizations become enhanced, revealing strong Coulomb correlations and electronic anisotropy, yielding a two-dimensional-like system. Our result shows the importance of strong electronic, interlayer and intralayer correlations in determining electronic structure and opens up applications of utilizing TMDCs on plasmonic nanolithrography.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Electronic correlations play important roles in driving exotic phenomena in condensed matter physics. They determine low-energy properties through high-energy bands well-beyond optics. Great effort has been made to understand low-energy excitations such as low-energy excitons in transition metal dichalcogenides (TMDCs), however their high-energy bands and interlayer correlation remain mysteries. Herewith, by measuring temperature- and polarization-dependent complex dielectric and loss functions of bulk molybdenum disulphide from near-infrared to soft X-ray, supported with theoretical calculations, we discover unconventional soft X-ray correlated-plasmons with low-loss, and electronic transitions that reduce dimensionality and increase correlations, accompanied with significantly modified low-energy excitons. At room temperature, interlayer electronic correlations, together with the intralayer correlations in the c-axis, are surprisingly strong, yielding a three-dimensional-like system. Upon cooling, wide-range spectral-weight transfer occurs across a few tens of eV and in-plane p-d hybridizations become enhanced, revealing strong Coulomb correlations and electronic anisotropy, yielding a two-dimensional-like system. Our result shows the importance of strong electronic, interlayer and intralayer correlations in determining electronic structure and opens up applications of utilizing TMDCs on plasmonic nanolithrography. |
Trushin, Maxim; Neto, Castro A H Stability of a Rolled-Up Conformation State for Two-Dimensional Materials in Aqueous Solutions Journal Article PHYSICAL REVIEW LETTERS, 127 (15), 2021, ISSN: 0031-9007. @article{ISI:000705653300005, title = {Stability of a Rolled-Up Conformation State for Two-Dimensional Materials in Aqueous Solutions}, author = {Maxim Trushin and Castro A H Neto}, doi = {10.1103/PhysRevLett.127.156101}, times_cited = {0}, issn = {0031-9007}, year = {2021}, date = {2021-10-08}, journal = {PHYSICAL REVIEW LETTERS}, volume = {127}, number = {15}, publisher = {AMER PHYSICAL SOC}, address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, abstract = {Two-dimensional (2D) materials can roll up, forming stable scrolls under suitable conditions. However, the great diversity of materials and fabrication techniques has resulted in a huge parameter space significantly complicating the theoretical description of scrolls. In this Letter, we describe a universal binding energy of scrolls determined solely by their material parameters, the bending stiffness, and the Hamaker coefficient. Aiming to predict the stability of functionalized scrolls in water solutions, we consider the electrostatic double-layer repulsion force that may overcome the binding energy and flatten the scrolls. Our predictions are represented as comprehensive maps indicating the stable and unstable regions of a rolled-up conformation state in the space of material and external parameters. While focusing mostly on functionalized graphene in this work, our approach is applicable to the whole range of 2D materials able to form scrolls.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Two-dimensional (2D) materials can roll up, forming stable scrolls under suitable conditions. However, the great diversity of materials and fabrication techniques has resulted in a huge parameter space significantly complicating the theoretical description of scrolls. In this Letter, we describe a universal binding energy of scrolls determined solely by their material parameters, the bending stiffness, and the Hamaker coefficient. Aiming to predict the stability of functionalized scrolls in water solutions, we consider the electrostatic double-layer repulsion force that may overcome the binding energy and flatten the scrolls. Our predictions are represented as comprehensive maps indicating the stable and unstable regions of a rolled-up conformation state in the space of material and external parameters. While focusing mostly on functionalized graphene in this work, our approach is applicable to the whole range of 2D materials able to form scrolls. |
Carvalho, A; Trevisanutto, P E; Taioli, S; Neto, Castro A H Computational methods for 2D materials modelling Journal Article REPORTS ON PROGRESS IN PHYSICS, 84 (10), 2021, ISSN: 0034-4885. @article{ISI:000704454000001, title = {Computational methods for 2D materials modelling}, author = {A Carvalho and P E Trevisanutto and S Taioli and Castro A H Neto}, doi = {10.1088/1361-6633/ac2356}, times_cited = {0}, issn = {0034-4885}, year = {2021}, date = {2021-10-01}, journal = {REPORTS ON PROGRESS IN PHYSICS}, volume = {84}, number = {10}, publisher = {IOP Publishing Ltd}, address = {TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}, abstract = {Materials with thickness ranging from a few nanometers to a single atomic layer present unprecedented opportunities to investigate new phases of matter constrained to the two-dimensional plane. Particle-particle Coulomb interaction is dramatically affected and shaped by the dimensionality reduction, driving well-established solid state theoretical approaches to their limit of applicability. Methodological developments in theoretical modelling and computational algorithms, in close interaction with experiments, led to the discovery of the extraordinary properties of two-dimensional materials, such as high carrier mobility, Dirac cone dispersion and bright exciton luminescence, and inspired new device design paradigms. This review aims to describe the computational techniques used to simulate and predict the optical, electronic and mechanical properties of two-dimensional materials, and to interpret experimental observations. In particular, we discuss in detail the particular challenges arising in the simulation of two-dimensional constrained fermions and quasiparticles, and we offer our perspective on the future directions in this field.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Materials with thickness ranging from a few nanometers to a single atomic layer present unprecedented opportunities to investigate new phases of matter constrained to the two-dimensional plane. Particle-particle Coulomb interaction is dramatically affected and shaped by the dimensionality reduction, driving well-established solid state theoretical approaches to their limit of applicability. Methodological developments in theoretical modelling and computational algorithms, in close interaction with experiments, led to the discovery of the extraordinary properties of two-dimensional materials, such as high carrier mobility, Dirac cone dispersion and bright exciton luminescence, and inspired new device design paradigms. This review aims to describe the computational techniques used to simulate and predict the optical, electronic and mechanical properties of two-dimensional materials, and to interpret experimental observations. In particular, we discuss in detail the particular challenges arising in the simulation of two-dimensional constrained fermions and quasiparticles, and we offer our perspective on the future directions in this field. |