51
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Li J, Wang F. Water graphene contact surface investigated by pairwise potentials from force-matching PAW-PBE with dispersion correction. J Chem Phys 2018; 146:054702. [PMID: 28178833 DOI: 10.1063/1.4974921] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A pairwise additive atomistic potential was developed for modeling liquid water on graphene. The graphene-water interaction terms were fit to map the PAW-PBE-D3 potential energy surface using the adaptive force matching method. Through condensed phase force matching, the potential developed implicitly considers the many-body effects of water. With this potential, the graphene-water contact angle was determined to be 86° in good agreement with a recent experimental measurement of 85° ± 5° on fully suspended graphene. Furthermore, the PAW-PBE-D3 based model was used to study contact line hysteresis. It was found that the advancing and receding contact angles of water do agree on pristine graphene, however a long simulation time was required to reach the equilibrium contact angle. For water on suspended graphene, sharp peaks in the water density profile disappear when the flexibility of graphene was explicitly considered. The water droplet induces graphene to wrap around it leading to a slightly concave contact interface.
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Affiliation(s)
- Jicun Li
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - Feng Wang
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, USA
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52
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Xie Q, Alibakhshi MA, Jiao S, Xu Z, Hempel M, Kong J, Park HG, Duan C. Fast water transport in graphene nanofluidic channels. NATURE NANOTECHNOLOGY 2018; 13:238-245. [PMID: 29292381 DOI: 10.1038/s41565-017-0031-9] [Citation(s) in RCA: 121] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 11/17/2017] [Indexed: 06/07/2023]
Abstract
Superfast water transport discovered in graphitic nanoconduits, including carbon nanotubes and graphene nanochannels, implicates crucial applications in separation processes and energy conversion. Yet lack of complete understanding at the single-conduit level limits development of new carbon nanofluidic structures and devices with desired transport properties for practical applications. Here, we show that the hydraulic resistance and slippage of single graphene nanochannels can be accurately determined using capillary flow and a novel hybrid nanochannel design without estimating the capillary pressure. Our results reveal that the slip length of graphene in the graphene nanochannels is around 16 nm, albeit with a large variation from 0 to 200 nm regardless of the channel height. We corroborate this finding with molecular dynamics simulation results, which indicate that this wide distribution of the slip length is due to the surface charge of graphene as well as the interaction between graphene and its silica substrate.
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Affiliation(s)
- Quan Xie
- Department of Mechanical Engineering, Boston University, Boston, MA, USA
| | | | - Shuping Jiao
- Department of Engineering Mechanics and Center for Nano and Micro Mechanics, Tsinghua University, Beijing, China
| | - Zhiping Xu
- Department of Engineering Mechanics and Center for Nano and Micro Mechanics, Tsinghua University, Beijing, China
| | - Marek Hempel
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jing Kong
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Hyung Gyu Park
- Department of Mechanical and Process Engineering, Eidgenössische Technische Hochschule (ETH) Zürich, Zürich, Switzerland
| | - Chuanhua Duan
- Department of Mechanical Engineering, Boston University, Boston, MA, USA.
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53
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Liu J, Lai CY, Zhang YY, Chiesa M, Pantelides ST. Water wettability of graphene: interplay between the interfacial water structure and the electronic structure. RSC Adv 2018; 8:16918-16926. [PMID: 35540542 PMCID: PMC9080294 DOI: 10.1039/c8ra03509a] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 04/28/2018] [Indexed: 12/14/2022] Open
Abstract
Wettability of graphene is characterized from first principles.
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Affiliation(s)
- Jian Liu
- Department of Physics and Astronomy
- Vanderbilt University
- Tennessee 37235
- USA
| | - Chia-Yun Lai
- Laboratory for Energy and Nano-Sciences
- Khalifa University of Science and Technology
- Abu Dhabi
- United Arab Emirates
| | - Yu-Yang Zhang
- Department of Physics and Astronomy
- Vanderbilt University
- Tennessee 37235
- USA
| | - Matteo Chiesa
- Laboratory for Energy and Nano-Sciences
- Khalifa University of Science and Technology
- Abu Dhabi
- United Arab Emirates
| | - Sokrates T. Pantelides
- Department of Physics and Astronomy
- Vanderbilt University
- Tennessee 37235
- USA
- Department of Electrical Engineering and Computer Science
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54
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Pramanik C, Gissinger JR, Kumar S, Heinz H. Carbon Nanotube Dispersion in Solvents and Polymer Solutions: Mechanisms, Assembly, and Preferences. ACS NANO 2017; 11:12805-12816. [PMID: 29179536 DOI: 10.1021/acsnano.7b07684] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Debundling and dispersion of carbon nanotubes (CNTs) in polymer solutions play a major role in the preparation of carbon nanofibers due to early effects on interfacial ordering and mechanical properties. A roadblock toward ultrastrong fibers is the difficulty to achieve homogeneous dispersions of CNTs in polyacrylonitrile (PAN) and poly(methyl methacrylate) (PMMA) precursor solutions in solvents such as dimethyl sulfoxide (DMSO), N,N-dimethylacetamide (DMAc), and N,N-dimethylformamide (DMF). In this contribution, molecular dynamics simulations with accurate interatomic potentials for graphitic materials that include virtual π electrons are reported to analyze the interaction of pristine single wall CNTs with the solvents and polymer solutions at 25 °C. The results explain the barriers toward dispersion of SWCNTs and quantify CNT-solvent, polymer-solvent, as well as CNT-polymer interactions in atomic detail. Debundling of CNTs is overall endothermic and unfavorable with dispersion energies of +20 to +30 mJ/m2 in the pure solvents, + 20 to +40 mJ/m2 in PAN solutions, and +20 to +60 mJ/m2 in PMMA solutions. Differences arise due to molecular geometry, polar, van der Waals, and CH-π interactions. Among the pure solvents, DMF restricts CNT dispersion less due to the planar geometry and stronger van der Waals interactions. PAN and PMMA interact favorably with the pure solvents with dissolution energies of -0.7 to -1.1 kcal per mole monomer and -1.5 to -2.2 kcal per mole monomer, respectively. Adsorption of PMMA onto CNTs is stronger than that of PAN in all solvents as the molecular geometry enables more van der Waals contacts between alkyl groups and the CNT surface. Polar side groups in both polymers prefer interactions with the polar solvents. Higher polymer concentrations in solution lead to polymer aggregation via alkyl groups and reduce adsorption onto CNTs. PAN and PMMA solutions in DMSO and dilute solutions in DMF support CNT dispersion more than other combinations whereby the polymers significantly adsorb onto CNTs in DMSO solution. The observations by molecular simulations are consistent with available experimental data and solubility parameters and aid in the design of carbon nanofibers. The methods can be applied to other multiphase graphitic materials.
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Affiliation(s)
- Chandrani Pramanik
- Department of Chemical and Biological Engineering, University of Colorado at Boulder , Boulder, Colorado 80309, United States
| | - Jacob R Gissinger
- Department of Chemical and Biological Engineering, University of Colorado at Boulder , Boulder, Colorado 80309, United States
| | - Satish Kumar
- School of Materials Science and Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - Hendrik Heinz
- Department of Chemical and Biological Engineering, University of Colorado at Boulder , Boulder, Colorado 80309, United States
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55
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Bejagam KK, Singh S, Deshmukh SA. Development of non-bonded interaction parameters between graphene and water using particle swarm optimization. J Comput Chem 2017; 39:721-734. [PMID: 29266458 DOI: 10.1002/jcc.25141] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 11/15/2017] [Accepted: 11/27/2017] [Indexed: 01/21/2023]
Abstract
New Lennard-Jones parameters have been developed to describe the interactions between atomistic model of graphene, represented by REBO potential, and five commonly used all-atom water models, namely SPC, SPC/E, SPC/Fw, SPC/Fd, and TIP3P/Fs by employing particle swarm optimization (PSO) method. These new parameters were optimized to reproduce the macroscopic contact angle of water on a graphene sheet. The calculated line tension was in the order of 10-11 J/m for the droplets of all water models. Our molecular dynamics simulations indicate the preferential orientation of water molecules near graphene-water interface with one OH bond pointing toward the graphene surface. Detailed analysis of simulation trajectories reveals the presence of water molecules with ≤∼1, ∼2, and ∼4 hydrogen bonds at the surface of air-water interface, graphene-water interface, and bulk region of the water droplet, respectively. Presence of water molecules with ≤∼1 and ∼2 hydrogen bonds suggest the existence of water clusters of different sizes at these interfaces. The trends observed in the libration, bending, and stretching bands of the vibrational spectra are closely associated with these structural features of water. The inhomogeneity in hydrogen bond network of water at the air-water and graphene-water interface is manifested by broadening of the peaks in the libration band for water present at these interfaces. The stretching band for the molecules in water droplet shows a blue shift as compared to the pure bulk water, which conjecture the presence of weaker hydrogen bond network in a droplet. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Karteek K Bejagam
- Department of Chemical Engineering, Virginia Tech, Blacksburg, Virginia, 24061
| | - Samrendra Singh
- Case New Holland Industrial, 6900 Veterans Blvd, Burr Ridge, Illinois, 60527
| | - Sanket A Deshmukh
- Department of Chemical Engineering, Virginia Tech, Blacksburg, Virginia, 24061
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56
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Chae S, Jin Choi W, Sang Chae S, Jang S, Chang H, Lee TI, Kim YS, Lee JO. Graphene as a thin-film catalyst booster: graphene-catalyst interface plays a critical role. NANOTECHNOLOGY 2017; 28:495708. [PMID: 29048327 DOI: 10.1088/1361-6528/aa94b0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Due to its extreme thinness, graphene can transmit some surface properties of its underlying substrate, a phenomenon referred to as graphene transparency. Here we demonstrate the application of the transparency of graphene as a protector of thin-film catalysts and a booster of their catalytic efficiency. The photocatalytic degradation of dye molecules by ZnO thin films was chosen as a model system. A ZnO thin film coated with monolayer graphene showed greater catalytic efficiency and long-term stability than did bare ZnO. Interestingly, we found the catalytic efficiency of the graphene-coated ZnO thin film to depend critically on the nature of the bottom ZnO layer; graphene transferred to a relatively rough, sputter-coated ZnO thin film showed rather poor catalytic degradation of the dye molecules while a smooth sol-gel-synthesized ZnO covered with monolayer graphene showed enhanced catalytic degradation. Based on a systematic investigation of the interface between graphene and ZnO thin films, we concluded the transparency of graphene to be critically dependent on its interface with a supporting substrate. Graphene supported on an atomically flat substrate was found to efficiently transmit the properties of the substrate, but graphene suspended on a substrate with a rough nanoscale topography was completely opaque to the substrate properties. Our experimental observations revealed the morphology of the substrate to be a key factor affecting the transparency of graphene, and should be taken into account in order to optimally apply graphene as a protector of catalytic thin films and a booster of their catalysis.
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Affiliation(s)
- Sieun Chae
- Advanced Materials Division, Korea Research Institute of Chemical Technology (KRICT), Daejeon 34114, Republic of Korea. Program in Nano Science and Technology, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 08826, Republic of Korea
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57
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Choi BK, Lee IH, Kim J, Chang YJ. Tunable Wetting Property in Growth Mode-Controlled WS 2 Thin Films. NANOSCALE RESEARCH LETTERS 2017; 12:262. [PMID: 28395480 PMCID: PMC5383915 DOI: 10.1186/s11671-017-2030-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 03/29/2017] [Indexed: 05/15/2023]
Abstract
We report on a thickness-dependent wetting property of WS2/Al2O3 and WS2/SiO2/Si structures. We prepared WS2 films with gradient thickness by annealing thickness-controlled WO3 films at 800 °C in sulfur atmosphere. Raman spectroscopy measurements showed step-like variation in the thickness of WS2 over substrates several centimeters in dimension. On fresh surfaces, we observed a significant change in the water contact angle depending on film thickness and substrate. Transmission electron microscopy analysis showed that differences in the surface roughness of WS2 films can account for the contrasting wetting properties between WS2/Al2O3 and WS2/SiO2/Si. The thickness dependence of water contact angle persisted for longer than 2 weeks, which demonstrates the stability of these wetting properties when exposed to air contamination.
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Affiliation(s)
- Byoung Ki Choi
- Department of Physics, University of Seoul, Seoul, 02504 Republic of Korea
| | - In Hak Lee
- Department of Physics, University of Seoul, Seoul, 02504 Republic of Korea
| | - Jiho Kim
- Department of Physics, University of Seoul, Seoul, 02504 Republic of Korea
| | - Young Jun Chang
- Department of Physics, University of Seoul, Seoul, 02504 Republic of Korea
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58
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Tian T, Lin S, Li S, Zhao L, Santos EJG, Shih CJ. Doping-Driven Wettability of Two-Dimensional Materials: A Multiscale Theory. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:12827-12837. [PMID: 29058907 DOI: 10.1021/acs.langmuir.7b03165] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Engineering molecular interactions at two-dimensional (2D) materials interfaces enables new technological opportunities in functional surfaces and molecular epitaxy. Understanding the wettability of 2D materials represents the crucial first step toward quantifying the interplay between the interfacial forces and electric potential of 2D materials interfaces. Here we develop the first theoretical framework to model the wettability of the doped 2D materials by properly bridging the multiscale physical phenomena at the 2D interfaces, including (i) the change of 2D materials surface energy (atomistic scale, several angstroms), (ii) the molecular reorientation of liquid molecules adjacent to the interface (molecular scale, 100-101 nm), and (iii) the electrical double layer (EDL) formed in the liquid phase (mesoscopic scales, 100-104 nm). The latter two effects are found to be the major mechanisms responsible for the contact angle change upon doping, while the surface energy change of a pure 2D material has no net effect on the wetting property. When the doping level is electrostatically tuned, we demonstrate that 2D materials with high quantum capacitances (e.g., transition metal dichalcogenides, TMDCs) possess a wider range of tunability in the interfacial tension, under the same applied gate voltage. Furthermore, practical considerations such as defects and airborne contamination are also quantitatively discussed. Our analysis implies that the doping level can be another variable to modulate the wettability at 2D materials interfaces, as well as the molecular packing behavior on a 2D material-coated surface, essentially facilitating the interfacial engineering of 2D materials.
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Affiliation(s)
- Tian Tian
- Institute for Chemical and Bioengineering, ETH Zürich , Vladimir Prelog Weg 1, CH-8093 Zürich, Switzerland
| | - Shangchao Lin
- Department of Mechanical Engineering, Materials Science and Engineering Program, FAMU-FSU College of Engineering, Florida State University , Tallahassee, Florida 32310, United States
| | - Siyu Li
- Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University , Nanjing, Jiangsu 210096, China
| | - Lingling Zhao
- Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University , Nanjing, Jiangsu 210096, China
| | - Elton J G Santos
- School of Mathematics and Physics, Queen's University Belfast , Belfast BT7 1NN, United Kingdom
| | - Chih-Jen Shih
- Institute for Chemical and Bioengineering, ETH Zürich , Vladimir Prelog Weg 1, CH-8093 Zürich, Switzerland
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59
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Xu Q, Zhang W, Dong C, Sreeprasad TS, Xia Z. Biomimetic self-cleaning surfaces: synthesis, mechanism and applications. J R Soc Interface 2017; 13:rsif.2016.0300. [PMID: 27628170 DOI: 10.1098/rsif.2016.0300] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 08/18/2016] [Indexed: 12/24/2022] Open
Abstract
With millions of years of natural evolution, organisms have achieved sophisticated structures, patterns or textures with complex, spontaneous multifunctionality. Among all the fascinating characteristics observed in biosystems, self-cleaning ability is regarded as one of the most interesting topics in biomimicry because of its potential applications in various fields such as aerospace, energy conversion and biomedical and environmental protection. Recently, in-depth studies have been carried out on various compelling biostructures including lotus leaves, shark skins, butterfly wings and gecko feet. To understand and mimic their self-cleaning mechanisms in artificial structures, in this article, recent progress in self-cleaning techniques is discussed and summarized. Based on the underlying self-cleaning mechanisms, the methods are classified into two categories: self-cleaning with water and without water. The review gives a succinct account of the detailed mechanisms and biomimetic processes applied to create artificial self-cleaning materials and surfaces, and provides some examples of cutting-edge applications such as anti-reflection, water repellence, self-healing, anti-fogging and micro-manipulators. The prospectives and directions of future development are also briefly proposed.
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Affiliation(s)
- Quan Xu
- State Key Laboratory of Heavy Oil Processing, China University of Petroleum (Beijing), Beijing 102249, People's Republic of China
| | - Wenwen Zhang
- College of Textile, North Carolina State University, Raleigh, NC 27607, USA
| | - Chenbo Dong
- Department of Civil and Environmental Engineering, Rice University, Houston, TX 77005, USA
| | | | - Zhenhai Xia
- Department of Materials Science and Engineering, University of North Texas, Denton, TX 76203, USA
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60
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Giubileo F, Martucciello N, Di Bartolomeo A. Focus on graphene and related materials. NANOTECHNOLOGY 2017; 28:410201. [PMID: 28901299 DOI: 10.1088/1361-6528/aa848d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
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61
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A comprehensive review on wettability, desalination, and purification using graphene-based materials at water interfaces. Catal Today 2017. [DOI: 10.1016/j.cattod.2017.04.027] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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62
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Tian T, Shih CJ. Molecular Epitaxy on Two-Dimensional Materials: The Interplay between Interactions. Ind Eng Chem Res 2017. [DOI: 10.1021/acs.iecr.7b02669] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Tian Tian
- Institute for Chemical and
Bioengineering, ETH Zürich, Vladimir Prelog Weg 1, CH-8093 Zürich, Switzerland
| | - Chih-Jen Shih
- Institute for Chemical and
Bioengineering, ETH Zürich, Vladimir Prelog Weg 1, CH-8093 Zürich, Switzerland
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63
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Singla S, Anim-Danso E, Islam AE, Ngo Y, Kim SS, Naik RR, Dhinojwala A. Insight on Structure of Water and Ice Next to Graphene Using Surface-Sensitive Spectroscopy. ACS NANO 2017; 11:4899-4906. [PMID: 28448717 DOI: 10.1021/acsnano.7b01499] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The water/graphene interface has received considerable attention in the past decade due to its relevance in various potential applications including energy storage, sensing, desalination, and catalysis. Most of our knowledge about the interfacial water structure next to graphene stems from simulations, which use experimentally measured water contact angles (WCAs) on graphene (or graphite) to estimate the water-graphene interaction strength. However, the existence of a wide spectrum of reported WCAs on supported graphene and graphitic surfaces makes it difficult to interpret the water-graphene interactions. Here, we have used surface-sensitive infrared-visible sum frequency generation (SFG) spectroscopy to probe the interfacial water structure next to graphene supported on a sapphire substrate. In addition, the ice nucleation properties of graphene have been explored by performing in situ freezing experiments as graphitic surfaces are considered good ice nucleators. For graphene supported on sapphire, we observed a strong SFG peak associated with highly coordinated, ordered water next to graphene. Similar ordering was not detected next to bare sapphire, implying that the observed ordering of water molecules in the former case is a consequence of the presence of graphene. Our analysis indicates that graphene behaves like a hydrophobic (or negatively charged) surface, leading to enhanced ordering of water molecules. Although liquid water orders next to graphene, the ice formed is proton disordered. This research sheds light on water-graphene interactions relevant in optimizing the performance of graphene in various applications.
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Affiliation(s)
- Saranshu Singla
- Department of Polymer Science, The University of Akron , Akron, Ohio 44325-3909, United States
| | - Emmanuel Anim-Danso
- Department of Polymer Science, The University of Akron , Akron, Ohio 44325-3909, United States
- Solvay Speciality Polymers , 4500 McGinnis Ferry Road, Alpharetta, Georgia 30005, United States
| | | | | | | | | | - Ali Dhinojwala
- Department of Polymer Science, The University of Akron , Akron, Ohio 44325-3909, United States
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64
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An H, Tan BH, Moo JGS, Liu S, Pumera M, Ohl CD. Graphene Nanobubbles Produced by Water Splitting. NANO LETTERS 2017; 17:2833-2838. [PMID: 28394607 DOI: 10.1021/acs.nanolett.6b05183] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Graphene nanobubbles are of significant interest due to their ability to trap mesoscopic volumes of gas for various applications in nanoscale engineering. However, conventional protocols to produce such bubbles are relatively elaborate and require specialized equipment to subject graphite samples to high temperatures or pressures. Here, we demonstrate the formation of graphene nanobubbles between layers of highly oriented pyrolytic graphite (HOPG) with electrolysis. Although this process can also lead to the formation of gaseous surface nanobubbles on top of the substrate, the two types of bubbles can easily be distinguished using atomic force microscopy. We estimated the Young's modulus, internal pressure, and the thickness of the top membrane of the graphene nanobubbles. The hydrogen storage capacity can reach ∼5 wt % for a graphene nanobubble with a membrane that is four layers thick. The simplicity of our protocol paves the way for such graphitic nanobubbles to be utilized for energy storage and industrial applications on a wide scale.
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Affiliation(s)
- Hongjie An
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , Singapore 637371, Singapore
| | - Beng Hau Tan
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , Singapore 637371, Singapore
| | - James Guo Sheng Moo
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University , Singapore 637371, Singapore
| | - Sheng Liu
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , Singapore 637371, Singapore
| | - Martin Pumera
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University , Singapore 637371, Singapore
| | - Claus-Dieter Ohl
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , Singapore 637371, Singapore
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65
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Remote epitaxy through graphene enables two-dimensional material-based layer transfer. Nature 2017; 544:340-343. [DOI: 10.1038/nature22053] [Citation(s) in RCA: 289] [Impact Index Per Article: 41.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 03/03/2017] [Indexed: 12/23/2022]
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66
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Tu Q, Kim HS, Oweida TJ, Parlak Z, Yingling YG, Zauscher S. Interfacial Mechanical Properties of Graphene on Self-Assembled Monolayers: Experiments and Simulations. ACS APPLIED MATERIALS & INTERFACES 2017; 9:10203-10213. [PMID: 28230343 DOI: 10.1021/acsami.6b16593] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Self-assembled monolayers (SAMs) have been widely used to engineer the electronic properties of substrate-supported graphene devices. However, little is known about how the surface chemistry of SAMs affects the interfacial mechanical properties of graphene supported on SAMs. Fluctuations and changes in these properties affect the stress transfer between substrate and the supported graphene and thus the performance of graphene-based devices. The changes in interfacial mechanical properties can be characterized by measuring the out-of-plane elastic properties. Combining contact resonance atomic force microcopy experiments with molecular dynamics simulations, we show that the head group chemistry of a SAM, which affects the interfacial interactions, can have a significant effect on the out-of-plane elastic modulus of the graphene-SAM heterostructure. Graphene supported on hydrophobic SAMs leads to heterostructures stiffer than those of graphene supported on hydrophilic SAMs, which is largely due to fewer water molecules present at the graphene-SAM interface. Our results provide an important, and often overlooked, insight into the mechanical properties of substrate-supported graphene electronics.
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Affiliation(s)
- Qing Tu
- Department of Mechanical Engineering and Materials Science, Duke University , Durham, North Carolina 27708, United States
- NSF Research Triangle, Materials Research Science and Engineering Center , Durham, North Carolina 27708, United States
| | - Ho Shin Kim
- NSF Research Triangle, Materials Research Science and Engineering Center , Durham, North Carolina 27708, United States
- Department of Materials Science and Engineering, North Carolina State University , Raleigh, North Carolina 27695, United States
| | - Thomas J Oweida
- Department of Materials Science and Engineering, North Carolina State University , Raleigh, North Carolina 27695, United States
| | - Zehra Parlak
- Department of Mechanical Engineering and Materials Science, Duke University , Durham, North Carolina 27708, United States
| | - Yaroslava G Yingling
- NSF Research Triangle, Materials Research Science and Engineering Center , Durham, North Carolina 27708, United States
- Department of Materials Science and Engineering, North Carolina State University , Raleigh, North Carolina 27695, United States
| | - Stefan Zauscher
- Department of Mechanical Engineering and Materials Science, Duke University , Durham, North Carolina 27708, United States
- NSF Research Triangle, Materials Research Science and Engineering Center , Durham, North Carolina 27708, United States
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67
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Kozbial A, Trouba C, Liu H, Li L. Characterization of the Intrinsic Water Wettability of Graphite Using Contact Angle Measurements: Effect of Defects on Static and Dynamic Contact Angles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:959-967. [PMID: 28071919 DOI: 10.1021/acs.langmuir.6b04193] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Elucidating the intrinsic water wettability of the graphitic surface has increasingly attracted research interests, triggered by the recent finding that the well-established hydrophobicity of graphitic surfaces actually results from airborne hydrocarbon contamination. Currently, static water contact angle (WCA) is often used to characterize the intrinsic water wettability of graphitic surfaces. In the current paper, we show that because of the existence of defects, static WCA does not necessarily characterize the intrinsic water wettability. Freshly exfoliated graphite of varying qualities, characterized using atomic force microscopy and Raman spectroscopy, was studied using static, advancing, and receding WCA measurements. The results showed that graphite of different qualities (i.e., defect density) always has a similar advancing WCA, but it could have very different static and receding WCAs. This finding indicates that defects play an important role in contact angle measurements, and the static contact angle does not always represent the intrinsic water wettability of pristine graphite. On the basis of the experimental results, a qualitative model is proposed to explain the effect of defects on static, advancing, and receding contact angles. The model suggests that the advancing WCA reflects the intrinsic water wettability of pristine (defect-free) graphite. Our results showed that the advancing WCA for pristine graphite is 68.6°, which indicates that graphitic carbon is intrinsically mildly hydrophilic.
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Affiliation(s)
- Andrew Kozbial
- Department of Chemical & Petroleum Engineering, Swanson School of Engineering, ‡Department of Chemistry, and §Department of Mechanical Engineering & Materials Science, Swanson School of Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
| | - Charlie Trouba
- Department of Chemical & Petroleum Engineering, Swanson School of Engineering, ‡Department of Chemistry, and §Department of Mechanical Engineering & Materials Science, Swanson School of Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
| | - Haitao Liu
- Department of Chemical & Petroleum Engineering, Swanson School of Engineering, ‡Department of Chemistry, and §Department of Mechanical Engineering & Materials Science, Swanson School of Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
| | - Lei Li
- Department of Chemical & Petroleum Engineering, Swanson School of Engineering, ‡Department of Chemistry, and §Department of Mechanical Engineering & Materials Science, Swanson School of Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
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Chi X, Zhang J, Nshimiyimana JP, Hu X, Wu P, Liu S, Liu J, Chu W, Sun L. Wettability of monolayer graphene/single-walled carbon nanotube hybrid films. RSC Adv 2017. [DOI: 10.1039/c7ra09934g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
This work presents a method for fabricating monolayer graphene/single-walled carbon nanotube hybrid films. We found that the wettability of monolayer graphene has a half-transparent behaviour.
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Affiliation(s)
- Xiannian Chi
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication
- CAS Center for Excellence in Nanoscience
- National Centre for Nanoscience and Technology
- Beijing 100190
- China
| | - Jian Zhang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication
- CAS Center for Excellence in Nanoscience
- National Centre for Nanoscience and Technology
- Beijing 100190
- China
| | - Jean Pierre Nshimiyimana
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication
- CAS Center for Excellence in Nanoscience
- National Centre for Nanoscience and Technology
- Beijing 100190
- China
| | - Xiao Hu
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication
- CAS Center for Excellence in Nanoscience
- National Centre for Nanoscience and Technology
- Beijing 100190
- China
| | - Pei Wu
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication
- CAS Center for Excellence in Nanoscience
- National Centre for Nanoscience and Technology
- Beijing 100190
- China
| | - Siyu Liu
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication
- CAS Center for Excellence in Nanoscience
- National Centre for Nanoscience and Technology
- Beijing 100190
- China
| | - Jia Liu
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication
- CAS Center for Excellence in Nanoscience
- National Centre for Nanoscience and Technology
- Beijing 100190
- China
| | - Weiguo Chu
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication
- CAS Center for Excellence in Nanoscience
- National Centre for Nanoscience and Technology
- Beijing 100190
- China
| | - Lianfeng Sun
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication
- CAS Center for Excellence in Nanoscience
- National Centre for Nanoscience and Technology
- Beijing 100190
- China
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Abstract
Graphitic carbons are important solid materials with myriad applications including electrodes, adsorbents, catalyst support, and solid lubricants. Understanding the interaction between water and graphitic carbons is critically important for both fundamental material characterization and practical device fabrication because the water-graphitic interface is essential to many applications. Research interests in graphene and carbon nanotubes over the past decades have brought renewed interest to elucidate wettability of graphitic carbons and understand their interaction with the surrounding environment. Research on this topic can be traced back to the 1940s, and the prevailing notion has been that graphitic carbons are hydrophobic. Though there have been different voices, this conclusion is supported by many previous water contact angle tests and well accepted by the community since sp2 carbon is nonpolar in nature. However, recent results from our groups showed that graphitic surfaces are intrinsically mildly hydrophilic and adsorbed hydrocarbon contaminants from the ambient air render the surface hydrophobic. This unexpected finding challenges the long-lasting conception and could completely change the way graphitic materials are made, modeled, and modified. With several other research groups reporting similar findings, it is important for the community to realize the importance of airborne contamination on the surface-related properties of graphitic materials and revisit the intrinsic water-graphite interaction. This Account aims to summarize our recent work on water wettability of graphitic surfaces and discuss future research directions toward understanding the intrinsic water-graphite interaction. Historical perspective will first be provided highlighting the long accepted notion that graphite is hydrophobic along with a few reports suggesting otherwise. Next, our recent experimental data will be presented showing that pristine graphene and graphite are mildly hydrophilic; chemical analysis showed that hydrocarbons adsorb onto the clean surfaces thus rendering them hydrophobic. These results are further rationalized by analyzing the change in surface energy of the graphitic surfaces before and after hydrocarbon contamination. Facile methods to remove hydrocarbons from a contaminated surface will be discussed along with a convenient water treatment method that we developed to inhibit hydrocarbon adsorption onto a pristine graphitic surface. Implications of contamination will be illustrated through comparing the electrochemical activity of pristine and contaminated graphite. Lastly, consequences of these findings and future research directions to address a few important unanswered questions will be discussed.
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Affiliation(s)
- Andrew Kozbial
- Department of Chemical & Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Feng Zhou
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Zhiting Li
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Haitao Liu
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Lei Li
- Department of Chemical & Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- Department of Mechanical Engineering & Materials Science, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
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Yiapanis G, Makarucha AJ, Baldauf JS, Downton MT. Simulations of graphitic nanoparticles at air-water interfaces. NANOSCALE 2016; 8:19620-19628. [PMID: 27853794 DOI: 10.1039/c6nr06475b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The free energy associated with transferring a set of fullerene particles through a finite water layer is calculated using explicit solvent molecular dynamic simulations. Each fullerene particle is a carbon network of one or more spheroidal shells of graphitic carbon, and include single-shell (single-wall) or nested multi-shelled (nano-onions) structures ranging from 6 to 28 Å in radius. Corresponding changes in energy suggest a stronger affinity of carbon nano-onions for water compared to their single-shelled analogues. In the case of multi-shelled structures, the free energy profiles display a global minimum only in the bulk liquid indicating a high affinity of multi-shelled fullerene for complete hydration. Single-wall particles however, display a minimum at the air-water interface and for particles larger than 2 nm this minimum is a global minimum possessing a lower energy compared to the particle's state of complete hydration. While the propensity for single-shell particles to adsorb to the air-interface may increase with increasing particle size, there is an indication based on line tension calculations that larger single-shell particles may actually exhibit enhanced wetting compared to their smaller analogues.
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Affiliation(s)
- George Yiapanis
- IBM Research Australia, Lvl 5/204 Lygon St., Carlton, VIC 3053, Australia.
| | | | - Julia S Baldauf
- IBM Research Australia, Lvl 5/204 Lygon St., Carlton, VIC 3053, Australia.
| | - Matthew T Downton
- IBM Research Australia, Lvl 5/204 Lygon St., Carlton, VIC 3053, Australia.
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72
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Gurarslan A, Jiao S, Li TD, Li G, Yu Y, Gao Y, Riedo E, Xu Z, Cao L. Van der Waals Force Isolation of Monolayer MoS 2. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:10055-10060. [PMID: 27690280 DOI: 10.1002/adma.201601581] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 07/07/2016] [Indexed: 06/06/2023]
Abstract
Monolayer MoS2 can effectively screen the vdW interaction of underlying substrates with external systems by >90% because of the substantial increase in the separation between the substrate and external systems due to the presence of the monolayer. This substantial screening of vdW interactions by MoS2 monolayer is different from what reported at graphene.
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Affiliation(s)
- Alper Gurarslan
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, 27695, USA
- Department of Fiber and Polymer Science, North Carolina State University, Raleigh, NC, 27695, USA
| | - Shuping Jiao
- Department of Mechanical Engineering, Tsinghua University, Beijing, 100084, China
| | - Tai-De Li
- CUNY-Advanced Science Research Center, New York, NY, 10031, USA
- School of Physics, Georgia Institue of Technology, Atlanta, GA, 30332, USA
| | - Guoqing Li
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, 27695, USA
- Department of Fiber and Polymer Science, North Carolina State University, Raleigh, NC, 27695, USA
| | - Yiling Yu
- Department of Physics, North Carolina State University, Raleigh, NC, 27695, USA
| | - Yang Gao
- CUNY-Advanced Science Research Center, New York, NY, 10031, USA
- School of Physics, Georgia Institue of Technology, Atlanta, GA, 30332, USA
| | - Elisa Riedo
- CUNY-Advanced Science Research Center, New York, NY, 10031, USA
- School of Physics, Georgia Institue of Technology, Atlanta, GA, 30332, USA
- Department of Physics, CUNY-City College of New York, New York, NY, 10031, USA
- Phyics Program, CUNY-The Graduate Center, New York, NY, 10016, USA
| | - Zhiping Xu
- Department of Mechanical Engineering, Tsinghua University, Beijing, 100084, China
| | - Linyou Cao
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, 27695, USA
- Department of Physics, North Carolina State University, Raleigh, NC, 27695, USA
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Tabassian R, Oh JH, Kim S, Kim D, Ryu S, Cho SM, Koratkar N, Oh IK. Graphene-coated meshes for electroactive flow control devices utilizing two antagonistic functions of repellency and permeability. Nat Commun 2016; 7:13345. [PMID: 27796291 PMCID: PMC5095590 DOI: 10.1038/ncomms13345] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 09/21/2016] [Indexed: 11/29/2022] Open
Abstract
The wettability of graphene on various substrates has been intensively investigated for practical applications including surgical and medical tools, textiles, water harvesting, self-cleaning, oil spill removal and microfluidic devices. However, most previous studies have been limited to investigating the intrinsic and passive wettability of graphene and graphene hybrid composites. Here, we report the electrowetting of graphene-coated metal meshes for use as electroactive flow control devices, utilizing two antagonistic functions, hydrophobic repellency versus liquid permeability. Graphene coating was able to prevent the thermal oxidation and corrosion problems that plague unprotected metal meshes, while also maintaining its hydrophobicity. The shapes of liquid droplets and the degree of water penetration through the graphene-coated meshes were controlled by electrical stimuli based on the functional control of hydrophobic repellency and liquid permeability. Furthermore, using the graphene-coated metal meshes, we developed two active flow devices demonstrating the dynamic locomotion of water droplets and electroactive flow switching. The wettability properties of graphene hold promise for the realisation of flow control devices. Here, the authors demonstrate that the degree of water penetration through a nickel mesh coated with graphene can be controlled electrically, enabling dynamic locomotion of water droplets.
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Affiliation(s)
- Rassoul Tabassian
- Creative Research Initiative Center for Functionally Antagonistic Nano-Engineering, Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Jung-Hwan Oh
- Creative Research Initiative Center for Functionally Antagonistic Nano-Engineering, Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Sooyeun Kim
- Creative Research Initiative Center for Functionally Antagonistic Nano-Engineering, Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Donggyu Kim
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Seunghwa Ryu
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Seung-Min Cho
- New Business Division, Hanwha Techwin R&D Center, 6, Pangyo-ro 319beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do 13488, Republic of Korea
| | - Nikhil Koratkar
- Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180, USA.,Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180, USA
| | - Il-Kwon Oh
- Creative Research Initiative Center for Functionally Antagonistic Nano-Engineering, Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
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Govind Rajan A, Sresht V, Pádua AAH, Strano MS, Blankschtein D. Dominance of Dispersion Interactions and Entropy over Electrostatics in Determining the Wettability and Friction of Two-Dimensional MoS 2 Surfaces. ACS NANO 2016; 10:9145-9155. [PMID: 27575956 DOI: 10.1021/acsnano.6b04276] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The existence of partially ionic bonds in molybdenum disulfide (MoS2), as opposed to covalent bonds in graphene, suggests that polar (electrostatic) interactions should influence the interfacial behavior of two-dimensional MoS2 surfaces. In this work, using molecular dynamics simulations, we show that electrostatic interactions play a negligible role in determining not only the equilibrium contact angle on the MoS2 basal plane, which depends solely on the total interaction energy between the surface and the liquid, but also the friction coefficient and the slip length, which depend on the spatial variations in the interaction energy. While the former is found to result from the exponential decay of the electric potential above the MoS2 surface, the latter results from the trilayered sandwich structure of the MoS2 monolayer, which causes the spatial variations in dispersion interactions in the lateral direction to dominate over those in electrostatic interactions in the lateral direction. Further, we show that the nonpolarity of MoS2 is specific to the two-dimensional basal plane of MoS2 and that other planes (e.g., the zigzag plane) in MoS2 are polar with respect to interactions with water, thereby illustrating the role of edge effects, which could be important in systems involving vacancies or nanopores in MoS2. Finally, we simulate the temperature dependence of the water contact angle on MoS2 to show that the inclusion of entropy, which has been neglected in recent mean-field theories, is essential in determining the wettability of MoS2. Our findings reveal that the basal planes in graphene and MoS2 are unexpectedly similar in terms of their interfacial behavior.
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Affiliation(s)
- Ananth Govind Rajan
- Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Vishnu Sresht
- Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Agilio A H Pádua
- Institut de Chimie de Clermont-Ferrand, Université Blaise Pascal and CNRS , 63171 Aubière, France
| | - Michael S Strano
- Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Daniel Blankschtein
- Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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75
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Lin F, Du F, Huang J, Chau A, Zhou Y, Duan H, Wang J, Xiong C. Substrate effect modulates adhesion and proliferation of fibroblast on graphene layer. Colloids Surf B Biointerfaces 2016; 146:785-93. [DOI: 10.1016/j.colsurfb.2016.07.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 07/04/2016] [Accepted: 07/04/2016] [Indexed: 01/14/2023]
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76
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Meyer-Holdt J, Kanne T, Sestoft JE, Gejl A, Zeng L, Johnson E, Olsson E, Nygård J, Krogstrup P. Ag-catalyzed InAs nanowires grown on transferable graphite flakes. NANOTECHNOLOGY 2016; 27:365603. [PMID: 27479073 DOI: 10.1088/0957-4484/27/36/365603] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Semiconducting nanowires grown by quasi-van-der-Waals epitaxy on graphite flakes are a new class of hybrid materials that hold promise for scalable nanostructured devices within opto-electronics. Here we report on high aspect ratio and stacking fault free Ag-seeded InAs nanowires grown on exfoliated graphite flakes by molecular beam epitaxy. Ag catalyzes the InAs nanowire growth selectively on the graphite flakes and not on the underlying InAs substrates. This allows for easy transfer of the flexible graphite flakes with as-grown nanowire ensembles to arbitrary substrates by a micro-needle manipulator. Besides the possibilities for fabricating novel nanostructure device designs, we show how this method is used to study the parasitic growth and bicrystal match between the graphite flake and the nanowires by transmission electron microscopy.
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Affiliation(s)
- Jakob Meyer-Holdt
- Nano-Science Center, Center for Quantum Devices and Station Q Copenhagen, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark. University of Chinese Academy of Sciences, Sino-Danish Center for Education & Research (SDC), Beijing 100049, People's Republic of China
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77
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Effect of electric charging on the velocity of water flow in CNT. J Mol Model 2016; 22:198. [DOI: 10.1007/s00894-016-3071-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Accepted: 07/10/2016] [Indexed: 10/21/2022]
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78
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Kratzer M, Teichert C. Thin film growth of aromatic rod-like molecules on graphene. NANOTECHNOLOGY 2016; 27:292001. [PMID: 27299472 DOI: 10.1088/0957-4484/27/29/292001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Research on graphene (Gr) is a vastly expanding field due to its potential for technological applications. Its close structural and chemical relationship to conjugated organic molecules makes it a superior candidate as a transparent electrode material in organic electronics and optoelectronics. The growth of organic thin films-intensively investigated in the past few decades-has demonstrated the complexity in growth and nucleation processes arising from the anisotropy and spatial extension of the molecular building blocks. Choosing the small, conjugated rod-like molecules para-hexaphenyl and pentacene as model representatives for small organic molecules, we review recent findings in organic thin film growth on a variety of Gr substrates. Special attention is paid to the differences in the resulting growth arising from the various methods of Gr fabrication and support that affect both the Gr-molecule interfacing and the involved molecular diffusion processes.
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Affiliation(s)
- M Kratzer
- Institute of Physics, Montanuiversität Leoben, Franz Josef Straße 18, 8700 Leoben, Austria
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79
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Hong G, Han Y, Schutzius TM, Wang Y, Pan Y, Hu M, Jie J, Sharma CS, Müller U, Poulikakos D. On the Mechanism of Hydrophilicity of Graphene. NANO LETTERS 2016; 16:4447-53. [PMID: 27248183 DOI: 10.1021/acs.nanolett.6b01594] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
It is generally accepted that the hydrophilic property of graphene can be affected by the underlying substrate. However, the role of intrinsic vs substrate contributions and the related mechanisms are vividly debated. Here, we show that the intrinsic hydrophilicity of graphene can be intimately connected to the position of its Fermi level, which affects the interaction between graphene and water molecules. The underlying substrate, or dopants, can tune hydrophilicity by modulating the Fermi level of graphene. By shifting the Fermi level of graphene away from its Dirac point, via either chemical or electrical voltage doping, we show enhanced hydrophilicity with experiments and first principle simulations. Increased vapor condensation on graphene, induced by a simple shifting of its Fermi level, exemplifies applications in the area of interfacial transport phenomena.
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Affiliation(s)
- Guo Hong
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich , Sonneggstrasse 3, 8092 Zurich, Switzerland
| | - Yang Han
- Institute of Mineral Engineering, Division of Materials Science and Engineering, Faculty of Georesources and Materials Engineering, RWTH Aachen University , 52064 Aachen, Germany
| | - Thomas M Schutzius
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich , Sonneggstrasse 3, 8092 Zurich, Switzerland
| | - Yuming Wang
- Institute of Functional Nano & Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nano Science and Technology, Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University , Suzhou, Jiangsu 215123, P. R. China
| | - Ying Pan
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich , Sonneggstrasse 3, 8092 Zurich, Switzerland
| | - Ming Hu
- Institute of Mineral Engineering, Division of Materials Science and Engineering, Faculty of Georesources and Materials Engineering, RWTH Aachen University , 52064 Aachen, Germany
- Aachen Institute for Advanced Study in Computational Engineering Science (AICES), RWTH Aachen University , 52062 Aachen, Germany
| | - Jiansheng Jie
- Institute of Functional Nano & Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nano Science and Technology, Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University , Suzhou, Jiangsu 215123, P. R. China
| | - Chander S Sharma
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich , Sonneggstrasse 3, 8092 Zurich, Switzerland
| | - Ulrich Müller
- Empa, Swiss Federal Laboratories for Materials Science and Technology , Laboratory for Nanoscale Materials Science, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland
| | - Dimos Poulikakos
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich , Sonneggstrasse 3, 8092 Zurich, Switzerland
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80
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Ashraf A, Wu Y, Wang MC, Yong K, Sun T, Jing Y, Haasch RT, Aluru NR, Nam S. Doping-Induced Tunable Wettability and Adhesion of Graphene. NANO LETTERS 2016; 16:4708-4712. [PMID: 27351580 DOI: 10.1021/acs.nanolett.6b02228] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report that substrate doping-induced charge carrier density modulation leads to the tunable wettability and adhesion of graphene. Graphene's water contact angle changes by as much as 13° as a result of a 300 meV change in doping level. Upon either n- or p-type doping with subsurface polyelectrolytes, graphene exhibits increased hydrophilicity. Adhesion force measurements using a hydrophobic self-assembled monolayer-coated atomic force microscopy probe reveal enhanced attraction toward undoped graphene, consistent with wettability modulation. This doping-induced wettability modulation is also achieved via a lateral metal-graphene heterojunction or subsurface metal doping. Combined first-principles and atomistic calculations show that doping modulates the binding energy between water and graphene and thus increases its hydrophilicity. Our study suggests that the doping-induced modulation of the charge carrier density in graphene influences its wettability and adhesion [corrected]. This opens up unique and new opportunities for the tunable wettability and adhesion of graphene for advanced coating materials and transducers.
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Affiliation(s)
- Ali Ashraf
- Department of Mechanical Science and Engineering and ‡Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Yanbin Wu
- Department of Mechanical Science and Engineering and ‡Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Michael Cai Wang
- Department of Mechanical Science and Engineering and ‡Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Keong Yong
- Department of Mechanical Science and Engineering and ‡Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Tao Sun
- Department of Mechanical Science and Engineering and ‡Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Yuhang Jing
- Department of Mechanical Science and Engineering and ‡Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Richard T Haasch
- Department of Mechanical Science and Engineering and ‡Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Narayana R Aluru
- Department of Mechanical Science and Engineering and ‡Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - SungWoo Nam
- Department of Mechanical Science and Engineering and ‡Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
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81
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Shen X, Wang Z, Wu Y, Liu X, He YB, Kim JK. Multilayer Graphene Enables Higher Efficiency in Improving Thermal Conductivities of Graphene/Epoxy Composites. NANO LETTERS 2016; 16:3585-93. [PMID: 27140423 DOI: 10.1021/acs.nanolett.6b00722] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The effects of number of graphene layers (n) and size of multilayer graphene sheets on thermal conductivities (TCs) of their epoxy composites are investigated. Molecular dynamics simulations show that the in-plane TCs of graphene sheets and the TCs across the graphene/epoxy interface simultaneously increase with increasing n. However, such higher TCs of multilayer graphene sheets will not translate into higher TCs of bulk composites unless they have large lateral sizes to maintain their aspect ratios comparable to the monolayer counterparts. The benefits of using large, multilayer graphene sheets are confirmed by experiments, showing that the composites made from graphite nanoplatelets (n > 10) with over 30 μm in diameter deliver a TC of ∼1.5 W m(-1) K(-1) at only 2.8 vol %, consistently higher than those containing monolayer or few-layer graphene at the same graphene loading. Our findings offer a guideline to use cost-effective multilayer graphene as conductive fillers for various thermal management applications.
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Affiliation(s)
- Xi Shen
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong
| | - Zhenyu Wang
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong
| | - Ying Wu
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong
| | - Xu Liu
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong
| | - Yan-Bing He
- Engineering Laboratory for Functionalized Carbon Materials, Graduate School at Shenzhen, Tsinghua University , Shenzhen 518055, China
| | - Jang-Kyo Kim
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong
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82
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Zhang J, Jiao XL, Xia YG, Liu FF, Pang YP, Zhao XF, Chen DR. Enhanced Catalytic Activity in Liquid-Exfoliated FeOCl Nanosheets as a Fenton-Like Catalyst. Chemistry 2016; 22:9321-9. [DOI: 10.1002/chem.201600172] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Indexed: 11/10/2022]
Affiliation(s)
- Jian Zhang
- School of Chemistry and Chemical Engineering; Shandong University; Jinan 250100 P. R. China
| | - Xiu-Ling Jiao
- School of Chemistry and Chemical Engineering; Shandong University; Jinan 250100 P. R. China
- National Engineering Research Center for Colloidal Materials; Shandong University; Jinan 250100 P. R. China
| | - Yu-Guo Xia
- National Engineering Research Center for Colloidal Materials; Shandong University; Jinan 250100 P. R. China
| | - Fang-Fang Liu
- School of Chemistry and Chemical Engineering; Shandong University; Jinan 250100 P. R. China
| | - Ying-Ping Pang
- School of Chemistry and Chemical Engineering; Shandong University; Jinan 250100 P. R. China
| | - Xin-Fu Zhao
- School of Chemistry and Chemical Engineering; Shandong University; Jinan 250100 P. R. China
| | - Dai-Rong Chen
- School of Chemistry and Chemical Engineering; Shandong University; Jinan 250100 P. R. China
- National Engineering Research Center for Colloidal Materials; Shandong University; Jinan 250100 P. R. China
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83
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Ye Z, Egberts P, Han GH, Johnson ATC, Carpick RW, Martini A. Load-Dependent Friction Hysteresis on Graphene. ACS NANO 2016; 10:5161-5168. [PMID: 27110836 DOI: 10.1021/acsnano.6b00639] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Nanoscale friction often exhibits hysteresis when load is increased (loading) and then decreased (unloading) and is manifested as larger friction measured during unloading compared to loading for a given load. In this work, the origins of load-dependent friction hysteresis were explored through atomic force microscopy (AFM) experiments of a silicon tip sliding on chemical vapor deposited graphene in air, and molecular dynamics simulations of a model AFM tip on graphene, mimicking both vacuum and humid air environmental conditions. It was found that only simulations with water at the tip-graphene contact reproduced the experimentally observed hysteresis. The mechanisms underlying this friction hysteresis were then investigated in the simulations by varying the graphene-water interaction strength. The size of the water-graphene interface exhibited hysteresis trends consistent with the friction, while measures of other previously proposed mechanisms, such as out-of-plane deformation of the graphene film and irreversible reorganization of the water molecules at the shearing interface, were less correlated to the friction hysteresis. The relationship between the size of the sliding interface and friction observed in the simulations was explained in terms of the varying contact angles in front of and behind the sliding tip, which were larger during loading than unloading.
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Affiliation(s)
- Zhijiang Ye
- Department of Mechanical Engineering, University of California Merced , 5200 North Lake Road, Merced, California 95343, United States
| | - Philip Egberts
- Department of Mechanical and Manufacturing Engineering, University of Calgary , 40 Research Place NW, Calgary, Alberta T2L 1Y6, Canada
| | - Gang Hee Han
- Physics Division, Center for Integrated Nanostructure Physics, Sungkyunkwan University , Suwon 440-746, South Korea
| | | | | | - Ashlie Martini
- Department of Mechanical Engineering, University of California Merced , 5200 North Lake Road, Merced, California 95343, United States
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84
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Deng Y, Chen L, Liu Q, Yu J, Wang H. Nanoscale View of Dewetting and Coating on Partially Wetted Solids. J Phys Chem Lett 2016; 7:1763-1768. [PMID: 27115464 DOI: 10.1021/acs.jpclett.6b00620] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
There remain significant gaps in our ability to predict dewetting and wetting despite the extensive study over the past century. An important reason is the absence of nanoscopic knowledge about the processes near the moving contact line. This experimental study for the first time obtained the liquid morphology within 10 nm of the contact line, which was receding at low speed (U < 50 nm/s). The results put an end to long-standing debate about the microscopic contact angle, which turned out to be varying with the speed as opposed to the constant-angle assumption that has been frequently employed in modeling. Moreover, a residual film of nanometer thickness ubiquitously remained on the solid after the receding contact line passed. This microscopic residual film modified the solid surface and thus made dewetting far from a simple reverse of wetting. A complete scenario for dewetting and coating is provided.
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Affiliation(s)
- Yajun Deng
- Laboratory of Heat and Mass Transport at Micro-Nano Scale, College of Engineering, Peking University, and Key Lab of Theory and Technology for Advanced Batteries Materials , Beijing 100871, China
| | - Lei Chen
- Laboratory of Heat and Mass Transport at Micro-Nano Scale, College of Engineering, Peking University, and Key Lab of Theory and Technology for Advanced Batteries Materials , Beijing 100871, China
| | - Qiao Liu
- Laboratory of Heat and Mass Transport at Micro-Nano Scale, College of Engineering, Peking University, and Key Lab of Theory and Technology for Advanced Batteries Materials , Beijing 100871, China
| | - Jiapeng Yu
- Laboratory of Heat and Mass Transport at Micro-Nano Scale, College of Engineering, Peking University, and Key Lab of Theory and Technology for Advanced Batteries Materials , Beijing 100871, China
| | - Hao Wang
- Laboratory of Heat and Mass Transport at Micro-Nano Scale, College of Engineering, Peking University, and Key Lab of Theory and Technology for Advanced Batteries Materials , Beijing 100871, China
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85
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Surface stress of graphene layers supported on soft substrate. Sci Rep 2016; 6:25653. [PMID: 27166087 PMCID: PMC4863371 DOI: 10.1038/srep25653] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 04/20/2016] [Indexed: 01/11/2023] Open
Abstract
We obtain the surface stress of a single layer and multilayers of graphene supported on silicone substrates by measuring the deformation of the graphene-covered substrates induced by the surface tension of liquid droplets together with the Neumann’s triangle concept. We find that the surface stress of the graphene-covered substrate is significant larger than that of the bare substrate, and it increases with increasing graphene layers, and finally reaches a constant value of about 120 mN/m on three and more layers of graphene. This work demonstrates that the apparent surface stress of graphene-substrate systems can be tuned by the substrate and the graphene layers. The surface stress and the tuning effect of the substrate on it may have applications in design and characterization of graphene-based ultra-sensitive sensors and other devices. Moreover, the method may also be used to measure the surface stress of other ultrathin films supported on soft substrates.
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86
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Chen PY, Sodhi J, Qiu Y, Valentin TM, Steinberg RS, Wang Z, Hurt RH, Wong IY. Multiscale Graphene Topographies Programmed by Sequential Mechanical Deformation. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:3564-71. [PMID: 26996525 DOI: 10.1002/adma.201506194] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 01/26/2016] [Indexed: 05/23/2023]
Abstract
Multigenerational graphene oxide architectures can be programmed by specific sequences of mechanical deformations. Each new deformation results in a progressively larger set of features decorated by smaller preexisting patterns, indicating a structural "memory." It is shown that these multiscale architectures are superhydrophobic and display excellent functionality as electrochemical electrodes.
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Affiliation(s)
- Po-Yen Chen
- School of Engineering, Institute for Molecular and Nanoscale Innovation, Brown University, Providence, RI, 02912, USA
| | - Jaskiranjeet Sodhi
- School of Engineering, Institute for Molecular and Nanoscale Innovation, Brown University, Providence, RI, 02912, USA
| | - Yang Qiu
- School of Engineering, Institute for Molecular and Nanoscale Innovation, Brown University, Providence, RI, 02912, USA
| | - Thomas M Valentin
- School of Engineering, Institute for Molecular and Nanoscale Innovation, Brown University, Providence, RI, 02912, USA
| | - Ruben Spitz Steinberg
- School of Engineering, Institute for Molecular and Nanoscale Innovation, Brown University, Providence, RI, 02912, USA
| | - Zhongying Wang
- School of Engineering, Institute for Molecular and Nanoscale Innovation, Brown University, Providence, RI, 02912, USA
| | - Robert H Hurt
- School of Engineering, Institute for Molecular and Nanoscale Innovation, Brown University, Providence, RI, 02912, USA
| | - Ian Y Wong
- School of Engineering, Institute for Molecular and Nanoscale Innovation, Brown University, Providence, RI, 02912, USA
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87
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Ondarçuhu T, Thomas V, Nuñez M, Dujardin E, Rahman A, Black CT, Checco A. Wettability of partially suspended graphene. Sci Rep 2016; 6:24237. [PMID: 27072195 PMCID: PMC4829856 DOI: 10.1038/srep24237] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 03/22/2016] [Indexed: 11/18/2022] Open
Abstract
The dependence of the wettability of graphene on the nature of the underlying substrate remains only partially understood. Here, we systematically investigate the role of liquid-substrate interactions on the wettability of graphene by varying the area fraction of suspended graphene from 0 to 95% by means of nanotextured substrates. We find that completely suspended graphene exhibits the highest water contact angle (85° ± 5°) compared to partially suspended or supported graphene, regardless of the hydrophobicity (hydrophilicity) of the substrate. Further, 80% of the long-range water-substrate interactions are screened by the graphene monolayer, the wettability of which is primarily determined by short-range graphene-liquid interactions. By its well-defined chemical and geometrical properties, supported graphene therefore provides a model system to elucidate the relative contribution of short and long range interactions to the macroscopic contact angle.
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Affiliation(s)
- Thierry Ondarçuhu
- Nanosciences group, CEMES-CNRS, 29 rue Jeanne Marvig, Toulouse 31055, France
| | - Vincent Thomas
- Nanosciences group, CEMES-CNRS, 29 rue Jeanne Marvig, Toulouse 31055, France
| | - Marc Nuñez
- Nanosciences group, CEMES-CNRS, 29 rue Jeanne Marvig, Toulouse 31055, France
| | - Erik Dujardin
- Nanosciences group, CEMES-CNRS, 29 rue Jeanne Marvig, Toulouse 31055, France
| | - Atikur Rahman
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Charles T Black
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Antonio Checco
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA
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88
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Shearer CJ, Slattery AD, Stapleton AJ, Shapter JG, Gibson CT. Accurate thickness measurement of graphene. NANOTECHNOLOGY 2016; 27:125704. [PMID: 26894444 DOI: 10.1088/0957-4484/27/12/125704] [Citation(s) in RCA: 159] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Graphene has emerged as a material with a vast variety of applications. The electronic, optical and mechanical properties of graphene are strongly influenced by the number of layers present in a sample. As a result, the dimensional characterization of graphene films is crucial, especially with the continued development of new synthesis methods and applications. A number of techniques exist to determine the thickness of graphene films including optical contrast, Raman scattering and scanning probe microscopy techniques. Atomic force microscopy (AFM), in particular, is used extensively since it provides three-dimensional images that enable the measurement of the lateral dimensions of graphene films as well as the thickness, and by extension the number of layers present. However, in the literature AFM has proven to be inaccurate with a wide range of measured values for single layer graphene thickness reported (between 0.4 and 1.7 nm). This discrepancy has been attributed to tip-surface interactions, image feedback settings and surface chemistry. In this work, we use standard and carbon nanotube modified AFM probes and a relatively new AFM imaging mode known as PeakForce tapping mode to establish a protocol that will allow users to accurately determine the thickness of graphene films. In particular, the error in measuring the first layer is reduced from 0.1-1.3 nm to 0.1-0.3 nm. Furthermore, in the process we establish that the graphene-substrate adsorbate layer and imaging force, in particular the pressure the tip exerts on the surface, are crucial components in the accurate measurement of graphene using AFM. These findings can be applied to other 2D materials.
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Affiliation(s)
- Cameron J Shearer
- Centre for NanoScale Science and Technology, School of Chemical and Physical Sciences, Flinders University, Bedford Park, South Australia, 5042, Australia
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89
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Ozmaian M, Fathizadeh A, Jalalvand M, Ejtehadi MR, Allaei SMV. Diffusion and self-assembly of C60 molecules on monolayer graphyne sheets. Sci Rep 2016; 6:21910. [PMID: 26912386 PMCID: PMC4766508 DOI: 10.1038/srep21910] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 01/27/2016] [Indexed: 12/15/2022] Open
Abstract
The motion of a fullerene (C60) on 5 different types of graphyne is studied by all-atom molecular dynamics simulations and compared with former studies on the motion of C60 on graphene. The motion shows a diffusive behavior which consists of either a continuous motion or discrete movements between trapping sites depending on the type of the graphyne sheet. For graphyne-4 and graphyne-5, fullerenes could detach from the surface of the graphyne sheet at room temperature which was not reported for similar cases on graphene sheets. Collective motion of a group of fullerenes interacting with a graphyne studied and it is shown that fullerenes exhibit stable assemblies. Depending on the type of graphyne, these assemblies can have either single or double layers. The mobility of the assembled structures is also dependent on the type of the graphyne sheet. The observed properties of the motion suggests novel applications for the complexes of fullerene and monolayer graphynes.
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Affiliation(s)
- Masoumeh Ozmaian
- Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Tehran, Iran
| | - Arman Fathizadeh
- School of physics, Institute for research in fundamental sciences (IPM), Tehran, Iran
| | | | - Mohammad Reza Ejtehadi
- Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran, Iran.,Center of Excellence in Complex Systems and Condensed Matter (CSCM), Sharif University of Technology, Tehran 1458889694, Iran
| | - S Mehdi Vaez Allaei
- Department of physics, University of Tehran, Tehran 14395-547, Iran.,School of physics, Institute for research in fundamental sciences (IPM), Tehran, Iran
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90
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Wang W, Zhang H, Li S, Zhan Y. Influences of ambient temperature, surface fluctuation and charge density on wettability properties of graphene film. NANOTECHNOLOGY 2016; 27:075707. [PMID: 26783182 DOI: 10.1088/0957-4484/27/7/075707] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Some molecular dynamics simulations focusing on the interactions between graphene films and water droplets are carried out in this article to investigate the fluid-solid interfacial behavior of surface wettability. The wettability of an ideal graphene film is investigated at room temperature at the beginning of the simulations, then the influences of ambient temperature, surface fluctuation and charge density of the graphene film on the wetting behaviors of water droplets on the film are also discussed from three points of view, namely the interaction energy of the graphene and the water droplet, the mass density of water and the water contact angle on the graphene film. The simulation results indicate that the ideal graphene film is slightly hydrophobic and that both the ambient temperature and the fluctuation of the graphene film play a negative role during the wetting processes. The observations also show that, once charged, the wetting property of graphene changes massively, from slightly hydrophobic to super-hydrophilic.
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Affiliation(s)
- Weidong Wang
- School of Electrical and Mechanical Engineering, Xidian University, Xi'an 710071, People's Republic of China. State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710054, People's Republic of China
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91
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Kim E, Shim HW, Unithrattil S, Kim YH, Choi H, Ahn KJ, Kwak JS, Kim S, Yoon H, Im WB. Effective Heat Dissipation from Color-Converting Plates in High-Power White Light Emitting Diodes by Transparent Graphene Wrapping. ACS NANO 2016; 10:238-245. [PMID: 26649577 DOI: 10.1021/acsnano.5b06734] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We have developed a hybrid phosphor-in-glass plate (PGP) for application in a remote phosphor configuration of high-power white light emitting diodes (WLEDs), in which single-layer graphene was used to modulate the thermal characteristics of the PGP. The degradation of luminescence in the PGP following an increase in temperature could be prevented by applying single-layer graphene. First, it was observed that the emission intensity of the PGP was enhanced by about 20% with graphene wrapping. Notably, the surface temperature of the graphene-wrapped PGP (G-PGP) was found to be higher than that of the bare PGP, implying that the graphene layer effectively acted as a heat dissipation medium on the PGP surface to reduce the thermal quenching of the constituent phosphors. Moreover, these experimental observations were clearly verified through a two-dimensional cellular automata simulation technique and the underlying mechanisms were analyzed. As a result, the proposed G-PGP was found to be efficient in maintaining the luminescence properties of the WLED, and is a promising development in high power WLED applications. This research could be further extended to generate a new class of optical or optoelectronic materials with possible uses in a variety of applications.
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Affiliation(s)
| | | | | | | | | | | | - Joon Seop Kwak
- Department of Printed Electronics Engineering, Sunchon National University , Jeonnam 57922, South Korea
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92
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Heinz H, Ramezani-Dakhel H. Simulations of inorganic-bioorganic interfaces to discover new materials: insights, comparisons to experiment, challenges, and opportunities. Chem Soc Rev 2016; 45:412-48. [PMID: 26750724 DOI: 10.1039/c5cs00890e] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Natural and man-made materials often rely on functional interfaces between inorganic and organic compounds. Examples include skeletal tissues and biominerals, drug delivery systems, catalysts, sensors, separation media, energy conversion devices, and polymer nanocomposites. Current laboratory techniques are limited to monitor and manipulate assembly on the 1 to 100 nm scale, time-consuming, and costly. Computational methods have become increasingly reliable to understand materials assembly and performance. This review explores the merit of simulations in comparison to experiment at the 1 to 100 nm scale, including connections to smaller length scales of quantum mechanics and larger length scales of coarse-grain models. First, current simulation methods, advances in the understanding of chemical bonding, in the development of force fields, and in the development of chemically realistic models are described. Then, the recognition mechanisms of biomolecules on nanostructured metals, semimetals, oxides, phosphates, carbonates, sulfides, and other inorganic materials are explained, including extensive comparisons between modeling and laboratory measurements. Depending on the substrate, the role of soft epitaxial binding mechanisms, ion pairing, hydrogen bonds, hydrophobic interactions, and conformation effects is described. Applications of the knowledge from simulation to predict binding of ligands and drug molecules to the inorganic surfaces, crystal growth and shape development, catalyst performance, as well as electrical properties at interfaces are examined. The quality of estimates from molecular dynamics and Monte Carlo simulations is validated in comparison to measurements and design rules described where available. The review further describes applications of simulation methods to polymer composite materials, surface modification of nanofillers, and interfacial interactions in building materials. The complexity of functional multiphase materials creates opportunities to further develop accurate force fields, including reactive force fields, and chemically realistic surface models, to enable materials discovery at a million times lower computational cost compared to quantum mechanical methods. The impact of modeling and simulation could further be increased by the advancement of a uniform simulation platform for organic and inorganic compounds across the periodic table and new simulation methods to evaluate system performance in silico.
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Affiliation(s)
- Hendrik Heinz
- Department of Chemical and Biological Engineering, University of Colorado-Boulder, Boulder, CO 80309, USA.
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93
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Ramos-Alvarado B, Kumar S, Peterson GP. On the wettability transparency of graphene-coated silicon surfaces. J Chem Phys 2016; 144:014701. [DOI: 10.1063/1.4938499] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Bladimir Ramos-Alvarado
- The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Satish Kumar
- The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - G. P. Peterson
- The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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94
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Pykal M, Jurečka P, Karlický F, Otyepka M. Modelling of graphene functionalization. Phys Chem Chem Phys 2016; 18:6351-72. [DOI: 10.1039/c5cp03599f] [Citation(s) in RCA: 168] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
This perspective describes the available theoretical methods and models for simulating graphene functionalization based on quantum and classical mechanics.
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Affiliation(s)
- Martin Pykal
- Regional Centre of Advanced Technologies and Materials
- Department of Physical Chemistry
- Faculty of Science
- Palacký University Olomouc
- 771 46 Olomouc
| | - Petr Jurečka
- Regional Centre of Advanced Technologies and Materials
- Department of Physical Chemistry
- Faculty of Science
- Palacký University Olomouc
- 771 46 Olomouc
| | - František Karlický
- Regional Centre of Advanced Technologies and Materials
- Department of Physical Chemistry
- Faculty of Science
- Palacký University Olomouc
- 771 46 Olomouc
| | - Michal Otyepka
- Regional Centre of Advanced Technologies and Materials
- Department of Physical Chemistry
- Faculty of Science
- Palacký University Olomouc
- 771 46 Olomouc
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95
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Andrews JE, Sinha S, Chung PW, Das S. Wetting dynamics of a water nanodrop on graphene. Phys Chem Chem Phys 2016; 18:23482-93. [DOI: 10.1039/c6cp01936f] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Spreading of water nanodrop on supported and unsupported graphene reveals inertia-dominated behavior.
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Affiliation(s)
| | - Shayandev Sinha
- Department of Mechanical Engineering
- University of Maryland
- College Park
- USA
| | - Peter W. Chung
- Department of Mechanical Engineering
- University of Maryland
- College Park
- USA
| | - Siddhartha Das
- Department of Mechanical Engineering
- University of Maryland
- College Park
- USA
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96
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Dryden DM, Hopkins JC, Denoyer LK, Poudel L, Steinmetz NF, Ching WY, Podgornik R, Parsegian A, French RH. van der Waals Interactions on the Mesoscale: Open-Science Implementation, Anisotropy, Retardation, and Solvent Effects. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:10145-10153. [PMID: 25815562 DOI: 10.1021/acs.langmuir.5b00106] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The self-assembly of heterogeneous mesoscale systems is mediated by long-range interactions, including van der Waals forces. Diverse mesoscale architectures, built of optically and morphologically anisotropic elements such as DNA, collagen, single-walled carbon nanotubes, and inorganic materials, require a tool to calculate the forces, torques, interaction energies, and Hamaker coefficients that govern assembly in such systems. The mesoscale Lifshitz theory of van der Waals interactions can accurately describe solvent and temperature effects, retardation, and optically and morphologically anisotropic materials for cylindrical and planar interaction geometries. The Gecko Hamaker open-science software implementation of this theory enables new and sophisticated insights into the properties of important organic/inorganic systems: interactions show an extended range of magnitudes and retardation rates, DNA interactions show an imprint of base pair composition, certain SWCNT interactions display retardation-dependent nonmonotonicity, and interactions are mapped across a range of material systems in order to facilitate rational mesoscale design.
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Affiliation(s)
| | | | - Lin K Denoyer
- Deconvolution and Entropy Consulting, 755 Snyder Hill, Ithaca, New York 14850, United States
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97
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Chakradhar A, Sivapragasam N, Nayakasinghe MT, Burghaus U. Support effects in the adsorption of water on CVD graphene: an ultra-high vacuum adsorption study. Chem Commun (Camb) 2015; 51:11463-6. [PMID: 26088276 DOI: 10.1039/c5cc03827h] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Experimental data for water adsorption on CVD (chemical vapor deposition) graphene/SiO2 and graphene/Cu studied under ultra-high vacuum (UHV) conditions are discussed, focusing on support effects and hydrophobicity. Under UHV, it seems that graphene wettability is inversely related to wetting properties of the support. Graphene is not transparent to water wetting on the supports studied here.
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Affiliation(s)
- A Chakradhar
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA.
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98
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Kozbial A, Gong X, Liu H, Li L. Understanding the Intrinsic Water Wettability of Molybdenum Disulfide (MoS2). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:8429-35. [PMID: 26172421 DOI: 10.1021/acs.langmuir.5b02057] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
2D semiconductors allow for unique and ultrasensitive devices to be fabricated for applications ranging from clinical diagnosis instruments to low-energy light-emitting diodes (LEDs). Graphene has championed research in this field since it was first fabricated; however, its zero bandgap creates many challenges. Transition metal dichalcogenides (TMDCs), e.g., MoS2, have a direct bandgap which alleviates the challenge of creating a bandgap in graphene-based devices. Water wettability of MoS2 is critical to device fabrication/performance and MoS2 has been believed to be hydrophobic. Herein, we report that water contact angle (WCA) of freshly exfoliated MoS2 shows temporal evolution with an intrinsic WCA of 69.0 ± 3.8° that increases to 89.0 ± 3.1° after 1 day exposure to ambient air. ATR-FTIR and ellipsometry show that the fresh, intrinsically mildly hydrophilic MoS2 surface adsorbs hydrocarbons from ambient air and thus becomes hydrophobic.
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Affiliation(s)
| | | | - Haitao Liu
- ‡Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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99
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Ramos-Alvarado B, Kumar S, Peterson GP. Wettability of graphitic-carbon and silicon surfaces: MD modeling and theoretical analysis. J Chem Phys 2015; 143:044703. [DOI: 10.1063/1.4927083] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Bladimir Ramos-Alvarado
- The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Satish Kumar
- The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - G. P. Peterson
- The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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Yun J, Jeon W, Alam Khan F, Lee J, Baik S. Reverse capillary flow of condensed water through aligned multiwalled carbon nanotubes. NANOTECHNOLOGY 2015; 26:235701. [PMID: 25987473 DOI: 10.1088/0957-4484/26/23/235701] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Molecular transport through nanopores has recently received considerable attention as a result of advances in nanofabrication and nanomaterial synthesis technologies. Surprisingly, water transport investigations through carbon nanochannels resulted in two contradicting observations: extremely fast transport or rejection of water molecules. In this paper, we elucidate the mechanism of impeded water vapor transport through the interstitial space of aligned multiwalled carbon nanotubes (aligned-MWCNTs)--capillary condensation, agglomeration, reverse capillary flow, and removal by superhydrophobicity at the tip of the nanotubes. The origin of separation comes from the water's phase change from gas to liquid, followed by reverse capillary flow. First, the saturation water vapor pressure is decreased in a confined space, which is favorable for the phase change of incoming water vapor into liquid drops. Once continuous water meniscus is formed between the nanotubes by the adsoprtion and agglomeration of water molecules, a high reverse Laplace pressure is induced in the mushroom-shaped liquid meniscus at the entry region of the aligned-MWCNTs. The reverse Laplace pressure can be significantly enhanced by decreasing the pore size. Finally, the droplets pushed backward by the reverse Laplace pressure can be removed by superhydrophobicity at the tip of the aligned-MWCNTs. The analytical analysis was also supported by experiments carried out using 4 mm-long aligned-MWCNTs with different intertube distances. The water rejection rate and the separation factor increased as the intertube distance decreased, resulting in 90% and 10, respectively, at an intertube distance of 4 nm. This mechanism and nanotube membrane may be useful for energy-efficient water vapor separation and dehumidification.
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Affiliation(s)
- Jongju Yun
- Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Korea
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