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Gupta B, Ambekar RS, Tromer RM, Ghosal PS, Sinha R, Majumder A, Kumbhakar P, Ajayan PM, Galvao DS, Gupta AK, Tiwary CS. Development of a schwarzite-based moving bed 3D printed water treatment system for nanoplastic remediation. RSC Adv 2021; 11:19788-19796. [PMID: 35479224 PMCID: PMC9033670 DOI: 10.1039/d1ra03097c] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 05/20/2021] [Indexed: 01/22/2023] Open
Abstract
The impact of micro and nanoplastic debris on our aquatic ecosystem is among the most prominent environmental challenges we face today. In addition, nanoplastics create significant concern for environmentalists because of their toxicity and difficulty in separation and removal. Here we report the development of a 3D printed moving bed water filter (M-3DPWF), which can perform as an efficient nanoplastic scavenger. The enhanced separation of the nanoplastics happens due to the creation of a charged filter material that traps the more surface charged nanoparticles selectively. Synthetic contaminated water from polycarbonate waste has been tested with the filter, and enhanced nanoplastic removal has been achieved. The proposed filtration mechanism of surface-charge based water cleaning is further validated using density function theory (semi-empirical) based simulation. The filter has also shown good structural and mechanical stability in both static and dynamic water conditions. The field suitability of the novel treatment system has also been confirmed using water from various sources, such as sea, river, and pond. Our results suggest that the newly developed water filter can be used for the removal of floating nanoparticles in water as a robust advanced treatment system. The impact of micro and nanoplastic debris on our aquatic ecosystem is among the most prominent environmental challenges we face today.![]()
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Affiliation(s)
- Bramha Gupta
- School of Water Resources, Indian Institute of Technology Kharagpur Kharagpur 721302 India
| | - Rushikesh S Ambekar
- Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur Kharagpur 721302 India
| | - Raphael M Tromer
- Applied Physics Department, State University of Campinas - UNICAMP 13083-859-Campinas SP Brazil
| | - Partha Sarathi Ghosal
- School of Water Resources, Indian Institute of Technology Kharagpur Kharagpur 721302 India
| | - Rupal Sinha
- School of Water Resources, Indian Institute of Technology Kharagpur Kharagpur 721302 India
| | - Abhradeep Majumder
- School of Environmental Science and Engineering, Indian Institute of Technology Kharagpur Kharagpur 721302 India
| | - Partha Kumbhakar
- Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur Kharagpur 721302 India
| | - P M Ajayan
- Department of Materials Science and Nanoengineering, Smalley-Curl Institute, Rice University Houston Texas 77005 USA
| | - Douglas S Galvao
- Applied Physics Department, State University of Campinas - UNICAMP 13083-859-Campinas SP Brazil
| | - Ashok Kumar Gupta
- Environmental Engineering Division, Department of Civil Engineering, Indian Institute of Technology Kharagpur Kharagpur 721302 India
| | - Chandra Sekhar Tiwary
- Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur Kharagpur 721302 India
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2
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Bianco E, Rao R, Snure M, Back T, Glavin NR, McConney ME, Ajayan PM, Ringe E. Large-area ultrathin Te films with substrate-tunable orientation. Nanoscale 2020; 12:12613-12622. [PMID: 32510097 DOI: 10.1039/d0nr01251c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Anisotropy in a crystal structure can lead to large orientation-dependent variations of mechanical, optical, and electronic properties. Material orientation control can thus provide a handle to manipulate properties. Here, a novel sputtering approach for 2D materials enables growth of ultrathin (2.5-10 nm) tellurium films with rational control of the crystalline orientation templated by the substrate. The anisotropic Te 〈0001〉 helical chains align in the plane of the substrate on highly oriented pyrolytic graphite (HOPG) and orthogonally to MgO(100) substrates, as shown by polarized Raman spectroscopy and high-resolution electron microscopy. Furthermore, the films are shown to grow in a textured fashion on HOPG, in contrast with previous reports. These ultrathin Te films cover exceptionally large areas (>1 cm2) and are grown at low temperature (25 °C) affording the ability to accommodate a variety of substrates including flexible electronics. They are robust toward oxidation over a period of days and exhibit the non-centrosymmetric P3121 Te structure. Raman signals are acutely dependent on film thickness, suggesting that optical anisotropy persists and is even enhanced at the ultrathin limit. Hall effect measurements indicate orientation-dependent carrier mobility up to 19 cm2 V-1 s-1. These large-area, ultrathin Te films grown by a truly scalable, physical vapor deposition technique with rational control of orientation/thickness open avenues for controlled orientation-dependent properties in semiconducting thin films for applications in electronic and optoelectronic devices.
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Affiliation(s)
- Elisabeth Bianco
- Department of Chemistry, Rice University, 6100 Main Street, Houston, TX 77005, USA
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3
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Vinayasree S, Nitha TS, Tiwary CS, Ajayan PM, Joy PA, Anantharaman MR. Magnetically tunable liquid dielectric with giant dielectric permittivity based on core-shell superparamagnetic iron oxide. Nanotechnology 2018; 29:265707. [PMID: 29624504 DOI: 10.1088/1361-6528/aabc4e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A liquid dielectric based on a core-shell architecture having a superparamagnetic iron oxide core and a shell of silicon dioxide was synthesized. The frequency dependence of dielectric properties was evaluated for different concentrations of iron oxide. The dependence of magnetic field on the dielectric properties was also studied. Aqueous ferrofluid exhibited a giant dielectric constant of 6.4 × 105 at 0.1 MHz at a concentration of 0.2 vol% and the loss tangent was 3. The large rise in dielectric constant at room temperature is modelled and explained using percolation theory and Maxwell-Wagner-Sillars type polarization. The ferrofluid is presumed to consist of nanocapacitor networks which are wired in series along the lateral direction and parallel along longitudinal direction. On the application of an external magnetic field, the chain formation and its alignment results in the variation of dielectric permittivity.
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Affiliation(s)
- S Vinayasree
- Department of Physics, Cochin University of Science and Technology, Kochi 682022, India. Department of Physics, KKTM Government College, Kodungallur, Thrissur 680 663, India
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4
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Soto M, Vajtai R, Ajayan PM, Barrera EV. Carbon nanotube conditioning part 1-effect of interwall interaction on the electronic band gap of double-walled carbon nanotubes. Nanotechnology 2018; 29:045701. [PMID: 29199975 DOI: 10.1088/1361-6528/aa9f05] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Ab initio density functional theory simulations were used to calculate the electronic structure and the total energy of double-walled carbon nanotubes (DWCNTs). The relaxed configurations studied were uncapped, infinitely-long zigzag@zigzag double-walled carbon nanotubes. The lowest energy configuration was found to correspond to an interwall distance of 0.35 nm, except for the configurations with inner tube chiral indices (5,0), (6,0) and (7,0). The largest binding energies were found to correspond to a 0.35 nm interwall distance for all the DWCNT configurations studied, and increasing with DWCNT average diameter. In terms of the effect of the interwall interaction on the electronic band gap of DWCNTs, four regions of band gap were obtained which were termed: zero band gap, narrow band gap, small band gap, and medium band gap regions. These regions offer the possibility to first tune the electronic band gap to a region with a desired range, and further tune that choice within the region itself by varying the interwall distance. It was also found that zigzag@zigzag DWCNTs with outer tube leading chiral index n = 3k + 1 or n = 3k + 2 (k being an integer) follow, as a general trend, an inversely proportional relation of the electronic band gap with respect to the average diameter.
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Affiliation(s)
- M Soto
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX 77005, United States of America
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5
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Sayed FN, Rodrigues MTF, Kalaga K, Gullapalli H, Ajayan PM. Curious Case of Positive Current Collectors: Corrosion and Passivation at High Temperature. ACS Appl Mater Interfaces 2017; 9:43623-43631. [PMID: 29182297 DOI: 10.1021/acsami.7b12675] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In the evaluation of compatibility of different components of cell for high-energy and extreme-conditions applications, the highly focused are positive and negative electrodes and their interaction with electrolyte. However, for high-temperature application, the other components are also of significant influence and contribute toward the total health of battery. In present study, we have investigated the behavior of aluminum, the most common current collector for positive electrode materials for its electrochemical and temperature stability. For electrochemical stability, different electrolytes, organic and room temperature ionic liquids with varying Li salts (LiTFSI, LiFSI), are investigated. The combination of electrochemical and spectroscopic investigations reflects the varying mechanism of passivation at room and high temperature, as different compositions of decomposed complexes are found at the surface of metals.
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Affiliation(s)
- Farheen N Sayed
- Department of Material Science and NanoEngineering, Rice University , Houston, Texas 77005, United States
| | - Marco-Tulio F Rodrigues
- Department of Material Science and NanoEngineering, Rice University , Houston, Texas 77005, United States
| | - Kaushik Kalaga
- Department of Material Science and NanoEngineering, Rice University , Houston, Texas 77005, United States
| | - Hemtej Gullapalli
- Department of Material Science and NanoEngineering, Rice University , Houston, Texas 77005, United States
| | - P M Ajayan
- Department of Material Science and NanoEngineering, Rice University , Houston, Texas 77005, United States
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6
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Núñez JD, Benito AM, Rouzière S, Launois P, Arenal R, Ajayan PM, Maser WK. Graphene oxide-carbon nanotube hybrid assemblies: cooperatively strengthened OH···O 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 C hydrogen bonds and the removal of chemisorbed water. Chem Sci 2017; 8:4987-4995. [PMID: 28989597 PMCID: PMC5625303 DOI: 10.1039/c7sc00223h] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 05/01/2017] [Indexed: 12/05/2022] Open
Abstract
The effective removal of chemisorbed water in graphene oxide by oxidized carbon nanotubes via cooperatively strengthened OH···OC hydrogen bonds.
Owing to their great significance for energy storage and sensing applications, multi-layer papers consisting of graphene oxide–carbon nanotube (GO–CNT) hybrid sheets were prepared by in situ exfoliation of graphite oxide in the presence of oxidized CNTs (oCNTs). For the first time we elucidate the influence of oCNTs on chemisorbed water (CW), i.e. the water molecules inherently bound to the oxygen functional groups (OFGs) of graphene oxide (GO) and responsible for irreversible structural damage upon thermal reduction processes. We show that oCNTs self-assemble onto GO sheets during the liquid phase processing steps by forming cooperatively strengthened OH···OC hydrogen bonds between the carboxylic groups of the oCNTs and OFGs of GO. At oCNT amounts of about 10 to 15 wt% this leads to the displacement of considerable amounts of CW without altering the original chemical composition of GO. The thermally reduced GO–CNT (rGO–CNT) papers reveal improved sp2 character and an enhancement of the specific capacitance by 75% with respect to thermally reduced GO (rGO), largely due to the effective removal of CW by oxidized CNTs. These findings disclose the relevance of the cooperative hydrogen bonding phenomena in graphene oxide paper/film electrodes for the development of improved electrochemical energy storage and sensing devices.
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Affiliation(s)
- J D Núñez
- Instituto de Carboquímica (ICB-CSIC) , E-50018 Zaragoza , Spain . ; Tel: +34 976 73 39 77
| | - A M Benito
- Instituto de Carboquímica (ICB-CSIC) , E-50018 Zaragoza , Spain . ; Tel: +34 976 73 39 77
| | - S Rouzière
- Laboratoire de Physique des Solides , CNRS , Univ. Paris-Sud , Univ. Paris Saclay , F-91405 Orsay Cedex , France
| | - P Launois
- Laboratoire de Physique des Solides , CNRS , Univ. Paris-Sud , Univ. Paris Saclay , F-91405 Orsay Cedex , France
| | - R Arenal
- Laboratorio de Microscopias Avanzadas , Instituto de Nanociencias de Aragón , Univ. Zaragoza , E-50018 Zaragoza , Spain.,ARAID Foundation , E-50018 Zaragoza , Spain
| | - P M Ajayan
- Department of Materials Science and NanoEngineering , Rice University , Houston , Texas 77005 , USA
| | - W K Maser
- Instituto de Carboquímica (ICB-CSIC) , E-50018 Zaragoza , Spain . ; Tel: +34 976 73 39 77
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7
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Gupta BK, Singh S, Kedawat G, Kumar P, Gangwar AK, Narayanan TN, Marti AA, Vajtai R, Ajayan PM. A novel electroluminescent device based on a reduced graphene oxide wrapped phosphor (ZnS:Cu,Al) and hexagonal-boron nitride for high-performance luminescence. Nanoscale 2017; 9:5002-5008. [PMID: 28383578 DOI: 10.1039/c6nr09302g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Reduced graphene oxide (rGO) has recently emerged as a very promising family of exotic carbon material with augmented performance in electronic and optoelectronic devices. Herein, we report an efficient and novel inorganic electroluminescent device geometry, where a new phosphor composite, reduced graphene oxide wrapped ZnS:Cu,Al, acts as an active emitting layer and an exfoliated hexagonal boron nitride (h-BN) as a dielectric layer. The roles of rGO in the active layer as a conductive support and local electric field enhancing agent are attributed to its wrinkles being unraveled compared with other carbon exotic nano-forms such as carbon nanotubes, graphite, charcoal and activated carbon, which significantly improves the brightness of the device (∼50 cd m-2 for 0.50 wt% rGO/ZnS:Cu,Al at 10 kHz and 110 V with an external quantum efficiency of ∼6.3% ± 0.1% and current efficiency of ∼0.81 ± 0.09 cd A-1). This new and facile strategy to construct the luminescent devices could be a paradigm shift towards cost effective, highly stable in air (for several days) and energy efficient next generation display devices.
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Affiliation(s)
- Bipin Kumar Gupta
- Luminescent Materials and Devices Group, Materials Physics and Engineering Division, CSIR-National Physical Laboratory, Dr K S Krishnan Road, New Delhi, 110012, India.
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8
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Blancon JC, Tsai H, Nie W, Stoumpos CC, Pedesseau L, Katan C, Kepenekian M, Soe CMM, Appavoo K, Sfeir MY, Tretiak S, Ajayan PM, Kanatzidis MG, Even J, Crochet JJ, Mohite AD. Extremely efficient internal exciton dissociation through edge states in layered 2D perovskites. Science 2017; 355:1288-1292. [DOI: 10.1126/science.aal4211] [Citation(s) in RCA: 688] [Impact Index Per Article: 98.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 02/22/2017] [Indexed: 01/20/2023]
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9
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He G, Ramamoorthy H, Kwan CP, Lee YH, Nathawat J, Somphonsane R, Matsunaga M, Higuchi A, Yamanaka T, Aoki N, Gong Y, Zhang X, Vajtai R, Ajayan PM, Bird JP. Thermally Assisted Nonvolatile Memory in Monolayer MoS 2 Transistors. Nano Lett 2016; 16:6445-6451. [PMID: 27680095 DOI: 10.1021/acs.nanolett.6b02905] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We demonstrate a novel form of thermally-assisted hysteresis in the transfer curves of monolayer MoS2 FETs, characterized by the appearance of a large gate-voltage window and distinct current levels that differ by a factor of ∼102. The hysteresis emerges for temperatures in excess of 400 K and, from studies in which the gate-voltage sweep parameters are varied, appears to be related to charge injection into the SiO2 gate dielectric. The thermally-assisted memory is strongly suppressed in equivalent measurements performed on bilayer transistors, suggesting that weak screening in the monolayer system plays a vital role in generating its strongly sensitive response to the charge-injection process. By exploiting the full features of the hysteretic transfer curves, programmable memory operation is demonstrated. The essential principles demonstrated here point the way to a new class of thermally assisted memories based on atomically thin two-dimensional semiconductors.
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Affiliation(s)
- G He
- Department of Electrical Engineering, University at Buffalo, The State University of New York , Buffalo, New York 14260-1900, United States
| | - H Ramamoorthy
- Department of Electrical Engineering, University at Buffalo, The State University of New York , Buffalo, New York 14260-1900, United States
| | - C-P Kwan
- Department of Physics, University at Buffalo, The State University of New York , Buffalo, New York 14260-1500, United States
| | - Y-H Lee
- Department of Electrical Engineering, University at Buffalo, The State University of New York , Buffalo, New York 14260-1900, United States
| | - J Nathawat
- Department of Electrical Engineering, University at Buffalo, The State University of New York , Buffalo, New York 14260-1900, United States
| | - R Somphonsane
- Department of Physics, King Mongkut's Institute of Technology Ladkrabang , Bangkok 10520, Thailand
| | - M Matsunaga
- Graduate School of Advanced Integration Science, Chiba University , 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - A Higuchi
- Graduate School of Advanced Integration Science, Chiba University , 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - T Yamanaka
- Graduate School of Advanced Integration Science, Chiba University , 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - N Aoki
- Graduate School of Advanced Integration Science, Chiba University , 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Y Gong
- Department of Materials Science and NanoEngineering, Rice University , Houston, Texas 77005, United States
| | - X Zhang
- Department of Materials Science and NanoEngineering, Rice University , Houston, Texas 77005, United States
| | - R Vajtai
- Department of Materials Science and NanoEngineering, Rice University , Houston, Texas 77005, United States
| | - P M Ajayan
- Department of Materials Science and NanoEngineering, Rice University , Houston, Texas 77005, United States
| | - J P Bird
- Department of Electrical Engineering, University at Buffalo, The State University of New York , Buffalo, New York 14260-1900, United States
- Graduate School of Advanced Integration Science, Chiba University , 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
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10
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Gautam C, Tiwary CS, Machado LD, Jose S, Ozden S, Biradar S, Galvao DS, Sonker RK, Yadav BC, Vajtai R, Ajayan PM. Synthesis and porous h-BN 3D architectures for effective humidity and gas sensors. RSC Adv 2016. [DOI: 10.1039/c6ra18833h] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
3D (three dimensional) architectures synthesised using an easily scalable solid state method which results in an interconnected network of porous h-BN sheets with boron trioxide are reported in this study.
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Affiliation(s)
- Chandkiram Gautam
- Department of Materials Science and Nano Engineering
- Rice University
- Houston
- USA
- Department of Physics
| | | | - Leonardo D. Machado
- Instituto de Física “Gleb Wataghin”
- Universidade Estadual de Campinas
- 13083-970 Campinas
- Brazil
| | - Sujin Jose
- Department of Materials Science and Nano Engineering
- Rice University
- Houston
- USA
- Department of Physics
| | - Sehmus Ozden
- Department of Materials Science and Nano Engineering
- Rice University
- Houston
- USA
| | | | - Douglas S. Galvao
- Instituto de Física “Gleb Wataghin”
- Universidade Estadual de Campinas
- 13083-970 Campinas
- Brazil
| | - Rakesh K. Sonker
- Department of Applied Physics
- School of Physical Sciences
- Babasaheb Bhimrao Ambedkar University
- Lucknow – 226025
- India
| | - B. C. Yadav
- Department of Applied Physics
- School of Physical Sciences
- Babasaheb Bhimrao Ambedkar University
- Lucknow – 226025
- India
| | - Robert Vajtai
- Department of Materials Science and Nano Engineering
- Rice University
- Houston
- USA
| | - P. M. Ajayan
- Department of Materials Science and Nano Engineering
- Rice University
- Houston
- USA
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11
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Jose SP, Tiwary CS, Kosolwattana S, Raghavan P, Machado LD, Gautam C, Prasankumar T, Joyner J, Ozden S, Galvao DS, Ajayan PM. Enhanced supercapacitor performance of a 3D architecture tailored using atomically thin rGO–MoS2 2D sheets. RSC Adv 2016. [DOI: 10.1039/c6ra20960b] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
A stable, conductive, additive-free and scalable 3D architecture supercapacitor electrode fabricated by atomically thin 2D sheets of GO and MoS2 shows superior electrochemical properties which are further substantiated using MD simulations.
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Affiliation(s)
- Sujin P. Jose
- Department of Materials Science and Nano Engineering
- Rice University
- Houston
- USA-77005
- School of Physics
| | | | | | - Prasanth Raghavan
- Department of Materials Science and Nano Engineering
- Rice University
- Houston
- USA-77005
| | - Leonardo D. Machado
- Department of Materials Science and Nano Engineering
- Rice University
- Houston
- USA-77005
- Department of Applied Physics
| | - Chandkiram Gautam
- Department of Materials Science and Nano Engineering
- Rice University
- Houston
- USA-77005
- Department of Physics
| | - T. Prasankumar
- School of Physics
- Madurai Kamaraj University
- Madurai-625021
- India
| | - Jarin Joyner
- Department of Materials Science and Nano Engineering
- Rice University
- Houston
- USA-77005
| | - Sehmus Ozden
- Department of Materials Science and Nano Engineering
- Rice University
- Houston
- USA-77005
| | - Douglas S. Galvao
- Department of Applied Physics
- State University of Campinas
- Campinas
- Brazil
| | - P. M. Ajayan
- Department of Materials Science and Nano Engineering
- Rice University
- Houston
- USA-77005
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12
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He G, Ghosh K, Singisetti U, Ramamoorthy H, Somphonsane R, Bohra G, Matsunaga M, Higuchi A, Aoki N, Najmaei S, Gong Y, Zhang X, Vajtai R, Ajayan PM, Bird JP. Conduction Mechanisms in CVD-Grown Monolayer MoS2 Transistors: From Variable-Range Hopping to Velocity Saturation. Nano Lett 2015; 15:5052-8. [PMID: 26121164 DOI: 10.1021/acs.nanolett.5b01159] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We fabricate transistors from chemical vapor deposition-grown monolayer MoS2 crystals and demonstrate excellent current saturation at large drain voltages (Vd). The low-field characteristics of these devices indicate that the electron mobility is likely limited by scattering from charged impurities. The current-voltage characteristics exhibit variable range hopping at low Vd and evidence of velocity saturation at higher Vd. This work confirms the excellent potential of MoS2 as a possible channel-replacement material and highlights the role of multiple transport phenomena in governing its transistor action.
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Affiliation(s)
- G He
- †Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-1900, United States
| | - K Ghosh
- †Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-1900, United States
| | - U Singisetti
- †Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-1900, United States
| | - H Ramamoorthy
- †Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-1900, United States
| | - R Somphonsane
- ‡Department of Physics, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand
| | - G Bohra
- †Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-1900, United States
| | - M Matsunaga
- §Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - A Higuchi
- §Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - N Aoki
- §Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - S Najmaei
- ∥Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - Y Gong
- ∥Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - X Zhang
- ∥Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - R Vajtai
- ∥Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - P M Ajayan
- ∥Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - J P Bird
- †Department of Electrical Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-1900, United States
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13
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Kundu S, Yadav RM, Narayanan TN, Shelke MV, Vajtai R, Ajayan PM, Pillai VK. Synthesis of N, F and S co-doped graphene quantum dots. Nanoscale 2015; 7:11515-11519. [PMID: 26087457 DOI: 10.1039/c5nr02427g] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Graphene quantum dots (GQDs) are a promising category of materials with remarkable size dependent properties like tunable bandgap and photoluminescence along with the possibility of effective chemical functionalization. Doping of GQDs with heteroatoms is an interesting way of regulating their properties. Herein, we report a facile and scalable one-step synthesis of luminescent GQDs, substitutionally co-doped with N, F and S, of ∼2 nm average size by a microwave treatment of multi-walled carbon nanotubes in a customized ionic liquid medium. The use of an ionic liquid coupled with the use of a microwave technique enables not only an ultrafast process for the synthesis of co-doped GQDs, but also provides excellent photoluminescence quantum yield (70%), perhaps due to the interaction of defect clusters and dopants.
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Affiliation(s)
- Sumana Kundu
- Academy of Scientific & Innovative Research, Chennai, 600113, India
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14
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Thanikaivelan P, Narayanan TN, Gupta BK, Reddy ALM, Ajayan PM. Nanobiocomposite from Collagen Waste Using Iron Oxide Nanoparticles and Its Conversion Into Magnetic Nanocarbon. J Nanosci Nanotechnol 2015; 15:4504-4509. [PMID: 26369072 DOI: 10.1166/jnn.2015.9720] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Collagenous wastes discarded from leather industry were stabilized using superparamagnetic iron oxide nanoparticles and further converted into a magnetic nanocarbon. Stabilization of collagen using iron oxide nanoparticles treatment (25% offer) was confirmed through differential scanning calorimetric analysis and further evidenced through scanning electron microscopic analysis. A simple high temperature treatment of the collagen-iron oxide nanoparticle composite at 850 degrees C for 2 h under Ar atmosphere yielded a bi-functional, magnetic and conducting, nanocarbon. The X-ray diffraction and Raman spectroscopic analysis reveal the partial graphitation and X-ray photoelectron spectroscopic results show the presence of trace-iron containing carbon, naturally doped with nitrogen and oxygen. Transmission electron microscopic analysis show the presence of larger iron oxide nanocrystals embedded in graphitic carbon layers while superconducting quantum interference device based analysis reveals a perfect ferrimagnetic property with saturation magnetization. Thus, we have stabilized the collagen waste fibers using iron oxide nanoparticles and converted them into a bi-functional nanocarbon, which has potential for various applications including energy, leather making and environmental remediation.
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15
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Soto M, Boyer TA, Biradar S, Ge L, Vajtai R, Elías-Zúñiga A, Ajayan PM, Barrera EV. Effect of interwall interaction on the electronic structure of double-walled carbon nanotubes. Nanotechnology 2015; 26:165201. [PMID: 25816374 DOI: 10.1088/0957-4484/26/16/165201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Through this study, the results of density functional theory calculations within the local density approximation of the electronic structure of zigzag-zigzag double-walled carbon nanotubes (DWCNTs), with chiral indices (n, 0)@(m, 0) for n = 7-15, and m = 15-26, has been presented and the effects of interwall interaction and orbital hybridization on the electronic structure of these systems has been discussed. It was observed that the electronic band gap of the aforementioned DWCNTs depends on the interwall distance only for metallic-semiconductor configurations and on the intrinsic properties of the constituent tubes in all other combinations. It was also observed that the calculated band gap for most of the metallic-metallic DWCNTs was smaller than semiconductor-metallic, metallic-semiconductor, and semiconductor-semiconductor configurations. Metallic-semiconductor DWCNTs were found to be desirable for band gap tuning applications because of their dependence on interwall distance, opening up the possibility of using such systems in electronic device applications, such as transistors. Other applications include the use of DWCNTs in macroscopic carbon nanotube conducting wires, for which metallic-metallic and semiconducting-metallic zigzag-zigzag DWCNTs were found to be the most desirable configurations due to their small band gaps.
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Affiliation(s)
- M Soto
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX 77005, USA
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16
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Abstract
We report the design and synthesis of a polymer structure from a cross-linkable epoxy–ionic liquid system which behaves like a hard and brittle epoxy thermoset, perfectly ductile thermoplastic and an elastomer, all depending on controllable network compositions.
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Affiliation(s)
- N. Hameed
- Carbon Nexus
- Deakin University
- Geelong
- Australia
| | - N. V. Salim
- Carbon Nexus
- Deakin University
- Geelong
- Australia
| | - T. R. Walsh
- Carbon Nexus
- Deakin University
- Geelong
- Australia
| | - J. S. Wiggins
- School of Polymers and High Performance Materials
- University of Southern Mississippi
- Hattiesburg
- USA
| | - P. M. Ajayan
- Department of Materials Science and NanoEngineering
- Rice University
- Houston
- USA
| | - B. L. Fox
- Carbon Nexus
- Deakin University
- Geelong
- Australia
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17
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Sudeep PM, Vinod S, Ozden S, Sruthi R, Kukovecz A, Konya Z, Vajtai R, Anantharaman MR, Ajayan PM, Narayanan TN. Functionalized boron nitride porous solids. RSC Adv 2015. [DOI: 10.1039/c5ra19091f] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A demonstration of the chemical functionalization of h-BN flakes and a template free approach for the development of macroscopic porous h-BN solids.
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Affiliation(s)
- P. M. Sudeep
- TIFR-Centre for Interdisciplinary Sciences
- Tata Institute of Fundamental Research
- Hyderabad-500075
- India
| | - S. Vinod
- Materials Science and NanoEngineering Department
- Rice University
- Houston
- USA
| | - S. Ozden
- Materials Science and NanoEngineering Department
- Rice University
- Houston
- USA
| | - R. Sruthi
- Materials Science and NanoEngineering Department
- Rice University
- Houston
- USA
| | - Akos Kukovecz
- Department of Applied and Environmental Chemistry
- University of Szeged
- H-6720 Szeged
- Hungary
- MTA-SZTE “Lendület” Porous Nanocomposites Research Group
| | - Zoltan Konya
- Department of Applied and Environmental Chemistry
- University of Szeged
- H-6720 Szeged
- Hungary
- MTA-SZTE Reaction Kinetics and Surface Chemistry Research Group
| | - Robert Vajtai
- Materials Science and NanoEngineering Department
- Rice University
- Houston
- USA
| | - M. R. Anantharaman
- Department of Physics
- Cochin University of Science and Technology
- Kochi-682022
- India
| | - P. M. Ajayan
- Materials Science and NanoEngineering Department
- Rice University
- Houston
- USA
| | - Tharangattu N. Narayanan
- TIFR-Centre for Interdisciplinary Sciences
- Tata Institute of Fundamental Research
- Hyderabad-500075
- India
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18
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Sano Y, Kawayama I, Tabata M, Salek KA, Murakami H, Wang M, Vajtai R, Ajayan PM, Kono J, Tonouchi M. Imaging molecular adsorption and desorption dynamics on graphene using terahertz emission spectroscopy. Sci Rep 2014; 4:6046. [PMID: 25116593 PMCID: PMC4131213 DOI: 10.1038/srep06046] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 07/22/2014] [Indexed: 11/10/2022] Open
Abstract
Being an atomically thin material, graphene is known to be extremely susceptible to its environment, including defects and phonons in the substrate on which it is placed as well as gas molecules that surround it. Thus, any device design using graphene has to take into consideration all surrounding components, and device performance needs to be evaluated in terms of environmental influence. However, no methods have been established to date to readily measure the density and distribution of external perturbations in a quantitative and non-destructive manner. Here, we present a rapid and non-contact method for visualizing the distribution of molecular adsorbates on graphene semi-quantitatively using terahertz time-domain spectroscopy and imaging. We found that the waveform of terahertz bursts emitted from graphene-coated InP sensitively changes with the type of atmospheric gas, laser irradiation time, and ultraviolet light illumination. The terahertz waveform change is explained through band structure modifications in the InP surface depletion layer due to the presence of localized electric dipoles induced by adsorbed oxygen. These results demonstrate that terahertz emission serves as a local probe for monitoring adsorption and desorption processes on graphene films and devices, suggesting a novel two-dimensional sensor for detecting local chemical reactions.
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Affiliation(s)
- Y Sano
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - I Kawayama
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - M Tabata
- NanoJapan Program and Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, USA
| | - K A Salek
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - H Murakami
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - M Wang
- 1] Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, USA [2] Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA
| | - R Vajtai
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA
| | - P M Ajayan
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA
| | - J Kono
- 1] Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan [2] NanoJapan Program and Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, USA [3] Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, USA [4] Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA [5] Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - M Tonouchi
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan
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19
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Vlad A, Singh N, Rolland J, Melinte S, Ajayan PM, Gohy JF. Hybrid supercapacitor-battery materials for fast electrochemical charge storage. Sci Rep 2014; 4:4315. [PMID: 24603843 PMCID: PMC3945924 DOI: 10.1038/srep04315] [Citation(s) in RCA: 191] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 02/20/2014] [Indexed: 12/22/2022] Open
Abstract
High energy and high power electrochemical energy storage devices rely on different fundamental working principles--bulk vs. surface ion diffusion and electron conduction. Meeting both characteristics within a single or a pair of materials has been under intense investigations yet, severely hindered by intrinsic materials limitations. Here, we provide a solution to this issue and present an approach to design high energy and high power battery electrodes by hybridizing a nitroxide-polymer redox supercapacitor (PTMA) with a Li-ion battery material (LiFePO4). The PTMA constituent dominates the hybrid battery charge process and postpones the LiFePO4 voltage rise by virtue of its ultra-fast electrochemical response and higher working potential. We detail on a unique sequential charging mechanism in the hybrid electrode: PTMA undergoes oxidation to form high-potential redox species, which subsequently relax and charge the LiFePO4 by an internal charge transfer process. A rate capability equivalent to full battery recharge in less than 5 minutes is demonstrated. As a result of hybrid's components synergy, enhanced power and energy density as well as superior cycling stability are obtained, otherwise difficult to achieve from separate constituents.
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Affiliation(s)
- A Vlad
- Institute of Information and Communication Technologies, Electronics and Applied Mathematics, Electrical Engineering, Université catholique de Louvain, Louvain la Neuve, B-1348 Belgium
| | - N Singh
- Department of Mechanical Engineering and Materials Science, Rice University, Houston, Texas 77005, United States
| | - J Rolland
- Institute of Condensed Matter and Nanosciences, Bio- and Soft Matter, Université catholique de Louvain, Louvain la Neuve, B-1348 Belgium
| | - S Melinte
- Institute of Information and Communication Technologies, Electronics and Applied Mathematics, Electrical Engineering, Université catholique de Louvain, Louvain la Neuve, B-1348 Belgium
| | - P M Ajayan
- Department of Mechanical Engineering and Materials Science, Rice University, Houston, Texas 77005, United States
| | - J-F Gohy
- Institute of Condensed Matter and Nanosciences, Bio- and Soft Matter, Université catholique de Louvain, Louvain la Neuve, B-1348 Belgium
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20
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Sridhar S, Ge L, Tiwary CS, Hart AC, Ozden S, Kalaga K, Lei S, Sridhar SV, Sinha RK, Harsh H, Kordas K, Ajayan PM, Vajtai R. Enhanced field emission properties from CNT arrays synthesized on Inconel superalloy. ACS Appl Mater Interfaces 2014; 6:1986-1991. [PMID: 24417432 DOI: 10.1021/am405026y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
One of the most promising materials for fabricating cold cathodes for next generation high-performance flat panel devices is carbon nanotubes (CNTs). For this purpose, CNTs grown on metallic substrates are used to minimize contact resistance. In this report, we compare properties and field emission performance of CNTs grown via water assisted chemical vapor deposition using Inconel vs silicon (Si) substrates. Carbon nanotube forests grown on Inconel substrates are superior to the ones grown on silicon; low turn-on fields (∼1.5 V/μm), high current operation (∼100 mA/cm(2)) and very high local field amplification factors (up to ∼7300) were demonstrated, and these parameters are most beneficial for use in vacuum microelectronic applications.
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Affiliation(s)
- S Sridhar
- Department of Applied Physics, Delhi Technological University (Formerly Delhi College of Engineering) , Bawana Road, Delhi 110042, India
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21
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Sudeep PM, Taha-Tijerina J, Ajayan PM, Narayanan TN, Anantharaman MR. Nanofluids based on fluorinated graphene oxide for efficient thermal management. RSC Adv 2014. [DOI: 10.1039/c4ra00843j] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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22
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Zhang J, Lu H, Sun Y, Ci L, Ajayan PM, Lou J. Humidity effects on anisotropic nanofriction behaviors of aligned carbon nanotube carpets. ACS Appl Mater Interfaces 2013; 5:9501-9507. [PMID: 24004024 DOI: 10.1021/am402221u] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We evaluated the interfacial properties of vertically and transversely aligned multiwalled carbon nanotubes (CNTs) carpets using atomic force microscopy (AFM) under ambient (26%-52% relative humidity (RH)), mild (10% RH), and dry conditions (<3.3% RH). The frictional forces on a transversely aligned CNT (TAMWCNT) surface are lower than those on a vertically aligned CNT (VAMWCNT) surface, and they decrease as the relative humidity decreases for both TAMWCNT and VAMWCNT surfaces. Similar trends are found for adhesion forces on both surfaces. Contact mechanics theories are applied and compared in an attempt to better understand these results. The tribological behavior of CNT carpets unveiled in this paper is expected to inspire tunable friction surface engineering strategies.
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Affiliation(s)
- J Zhang
- Department of Mechanical Engineering and Materials Science, Rice University , Houston, Texas 77005, United States
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23
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Damien D, Babu B, Narayanan TN, Reddy AL, Ajayan PM, Shaijumon MM. Eco-Efficient Synthesis of Graphene Nanoribbons and Its Application in Electrochemical Supercapacitors. ACTA ACUST UNITED AC 2013. [DOI: 10.1166/graph.2013.1002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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24
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Drexler C, Tarasenko SA, Olbrich P, Karch J, Hirmer M, Müller F, Gmitra M, Fabian J, Yakimova R, Lara-Avila S, Kubatkin S, Wang M, Vajtai R, Ajayan PM, Kono J, Ganichev SD. Magnetic quantum ratchet effect in graphene. Nat Nanotechnol 2013; 8:104-107. [PMID: 23334170 DOI: 10.1038/nnano.2012.231] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Accepted: 11/19/2012] [Indexed: 06/01/2023]
Abstract
A periodically driven system with spatial asymmetry can exhibit a directed motion facilitated by thermal or quantum fluctuations. This so-called ratchet effect has fascinating ramifications in engineering and natural sciences. Graphene is nominally a symmetric system. Driven by a periodic electric field, no directed electric current should flow. However, if the graphene has lost its spatial symmetry due to its substrate or adatoms, an electronic ratchet motion can arise. We report an experimental demonstration of such an electronic ratchet in graphene layers, proving the underlying spatial asymmetry. The orbital asymmetry of the Dirac fermions is induced by an in-plane magnetic field, whereas the periodic driving comes from terahertz radiation. The resulting magnetic quantum ratchet transforms the a.c. power into a d.c. current, extracting work from the out-of-equilibrium electrons driven by undirected periodic forces. The observation of ratchet transport in this purest possible two-dimensional system indicates that the orbital effects may appear and be substantial in other two-dimensional crystals such as boron nitride, molybdenum dichalcogenides and related heterostructures. The measurable orbital effects in the presence of an in-plane magnetic field provide strong evidence for the existence of structure inversion asymmetry in graphene.
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Affiliation(s)
- C Drexler
- Terahertz Center, University of Regensburg, 93040 Regensburg, Germany
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25
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Damien D, Sudeep PM, Narayanan TN, Anantharaman MR, Ajayan PM, Shaijumon MM. Fluorinated graphene based electrodes for high performance primary lithium batteries. RSC Adv 2013. [DOI: 10.1039/c3ra45377d] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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26
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Narayanan TN, Mandal BP, Tyagi AK, Kumarasiri A, Zhan X, Hahm MG, Anantharaman MR, Lawes G, Ajayan PM. Hybrid multiferroic nanostructure with magnetic-dielectric coupling. Nano Lett 2012; 12:3025-30. [PMID: 22545916 DOI: 10.1021/nl300849u] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The development of methods to economically synthesize single wire structured multiferroic systems with room temperature spin-charge coupling is expected to be important for building next-generation multifunctional devices with ultralow power consumption. We demonstrate the fabrication of a single nanowire multiferroic system, a new geometry, exhibiting room temperature magnetodielectric coupling. A coaxial nanotube/nanowire heterostructure of barium titanate (BaTiO(3), BTO) and cobalt (Co) has been synthesized using a template-assisted method. Room temperature ferromagnetism and ferroelectricity were exhibited by this coaxial system, indicating the coexistence of more than one ferroic interaction in this composite system.
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Affiliation(s)
- T N Narayanan
- Department of Mechanical Engineering and Materials Science, Rice University, Houston, Texas 77005, United States
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27
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Reena Mary AP, Suchand Sandeep CS, Narayanan TN, Philip R, Moloney P, Ajayan PM, Anantharaman MR. Nonlinear and magneto-optical transmission studies on magnetic nanofluids of non-interacting metallic nickel nanoparticles. Nanotechnology 2011; 22:375702. [PMID: 21852735 DOI: 10.1088/0957-4484/22/37/375702] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Oxide free stable metallic nanofluids have the potential for various applications such as in thermal management and inkjet printing apart from being a candidate system for fundamental studies. A stable suspension of nickel nanoparticles of ∼ 5 nm size has been realized by a modified two-step synthesis route. Structural characterization by x-ray diffraction and transmission electron microscopy shows that the nanoparticles are metallic and are phase pure. The nanoparticles exhibited superparamagnetic properties. The magneto-optical transmission properties of the nickel nanofluid (Ni-F) were investigated by linear optical dichroism measurements. The magnetic field dependent light transmission studies exhibited a polarization dependent optical absorption, known as optical dichroism, indicating that the nanoparticles suspended in the fluid are non-interacting and superparamagnetic in nature. The nonlinear optical limiting properties of Ni-F under high input optical fluence were then analyzed by an open aperture z-scan technique. The Ni-F exhibits a saturable absorption at moderate laser intensities while effective two-photon absorption is evident at higher intensities. The Ni-F appears to be a unique material for various optical devices such as field modulated gratings and optical switches which can be controlled by an external magnetic field.
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Affiliation(s)
- A P Reena Mary
- Department of Physics, Cochin University of Science and Technology, Cochin 682 022, India
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28
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Jia Y, Cao A, Bai X, Li Z, Zhang L, Guo N, Wei J, Wang K, Zhu H, Wu D, Ajayan PM. Achieving high efficiency silicon-carbon nanotube heterojunction solar cells by acid doping. Nano Lett 2011; 11:1901-5. [PMID: 21452837 DOI: 10.1021/nl2002632] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Various approaches to improve the efficiency of solar cells have followed the integration of nanomaterials into Si-based photovoltaic devices. Here, we achieve 13.8% efficiency solar cells by combining carbon nanotubes and Si and doping with dilute HNO(3). Acid infiltration of nanotube networks significantly boost the cell efficiency by reducing the internal resistance that improves fill factor and by forming photoelectrochemical units that enhance charge separation and transport. Compared to conventional Si cells, the fabrication process is greatly simplified, simply involving the transfer of a porous semiconductor-rich nanotube film onto an n-type crystalline Si wafer followed by acid infiltration.
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Affiliation(s)
- Yi Jia
- Key Laboratory for Advanced Materials Processing Technology and Department of Mechanical Engineering, Tsinghua University, Beijing 100084, People's Republic of China
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29
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Abstract
The adhesion and friction behavior of soft materials, including compliant brushes and hairs, depends on the temporal and spatial evolution of the interfaces in contact. For compliant nanofibrous materials, the actual contact area individual fibers make with surfaces depends on the preload applied upon contact. Using in situ microscopy observations of preloaded nanotube hairs, we show how nanotubes make cooperative contact with a surface by buckling and conforming to the surface topography. The overall adhesion of compliant nanohairs increases with increasing preload as nanotubes deform and continuously add new side-wall contacts with the surface. Electrical resistance measurements indicate significant hysteresis in the relative contact area. Contact area increases with preload (or stress) and decreases suddenly during unloading, consistent with strong adhesion observed for these complaint nanohairs.
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Affiliation(s)
- Liehui Ge
- Department of Polymer Science, The University of Akron, Akron, Ohio 44325, United States
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30
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Abstract
A simple technique is described here that produces aligned arrays of carbon nanotubes. The alignment method is based on cutting thin slices (50 to 200 nanometers) of a nanotube-polymer composite. With this parallel and well-separated configuration of nanotubes it should be possible to measure individual tube properties and to demonstrate applications. The results demonstrate the nature of rheology, on nanometer scales, in composite media and flow-induced anisotropy produced by the cutting process. The fact that nanotubes do not break and are straightened after the cutting process also suggests that they have excellent mechanical properties.
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31
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Ci L, Ajayan PM. Modifying surface structure to tune surface properties of vertically aligned carbon nanotube films. J Nanosci Nanotechnol 2010; 10:3854-3859. [PMID: 20355379 DOI: 10.1166/jnn.2010.2003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We report a simple etching process to modify surface of vertically aligned carbon nanotube (VACNT) arrays for their applications in superhydrophobic surface, field emission display, and sun energy conversion, etc. At a high temperature (700-800 degrees C), very low concentration water vapor in presence with Ar and hydrogen flow can be a weak oxidant, and mildly etch nanotube tips without damaging their walls. This process can be performed right after the CNT growth process. Surface of nanotube arrays becomes multi-tiered nanotube patterns with open-ended nanotubes standing straightly. Surface morphology of nanotube arrays can be tuned by changing the etching time. Water droplets on a modified nanotube surface show a large contact angle and sliding angle, which make the etched nanotube film suitable for application such as small amount liquid transport. Light absorption measurement indicated that surface roughness has no effect to improve the light absorption, indicating a different mechanism from other black material. The surface modified nanotube arrays have much increased field enhancement factor in our field emission test, showing the better field emission ability of the nanotube arrays with open tips.
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Affiliation(s)
- Lijie Ci
- Department of Mechanical Engineering and Materials Science, Rice University, Houston, TX 77005, USA
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32
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Essig S, Marquardt CW, Vijayaraghavan A, Ganzhorn M, Dehm S, Hennrich F, Ou F, Green AA, Sciascia C, Bonaccorso F, Bohnen KP, Löhneysen HV, Kappes MM, Ajayan PM, Hersam MC, Ferrari AC, Krupke R. Phonon-assisted electroluminescence from metallic carbon nanotubes and graphene. Nano Lett 2010; 10:1589-1594. [PMID: 20405819 DOI: 10.1021/nl9039795] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We report on light emission from biased metallic single-wall carbon nanotube (SWNT), multiwall carbon nanotube (MWNT) and few-layer graphene (FLG) devices. SWNT devices were assembled from tubes with different diameters in the range 0.7-1.5 nm. They emit light in the visible spectrum with peaks at 1.4 and 1.8 eV. Similar peaks are observed for MWNT and FLG devices. We propose that this light emission is due to phonon-assisted radiative decay from populated pi* band states at the M point to the Fermi level at the K point. Since for most carbon nanotubes as well as for graphene the energy of unoccupied states at the M point is close to 1.6 eV, the observation of two emission peaks at approximately 1.6 +/- approximately 0.2 eV could indicate radiative decay under emission or absorption of optical phonons, respectively.
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Affiliation(s)
- S Essig
- Institut für Nanotechnologie, Karlsruhe Institute of Technology, Karlsruhe, Germany
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33
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Kim YL, Li B, An X, Hahm MG, Chen L, Washington M, Ajayan PM, Nayak SK, Busnaina A, Kar S, Jung YJ. Highly aligned scalable platinum-decorated single-wall carbon nanotube arrays for nanoscale electrical interconnects. ACS Nano 2009; 3:2818-2826. [PMID: 19725514 DOI: 10.1021/nn9007753] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We present the fabrication and characterization of nanoscale electrical interconnect test structures constructed from aligned single-wall carbon nanotubes using a template-based fluidic assembly process. This CMOS-friendly process enables the formation of highly aligned parallel nanotube interconnect structures on SiO(2)/Si substrates of widths and lengths that are limited only by lithographical limits and, hence, can be easily integrated onto existing Si-based platforms. These structures can withstand current densities of approximately 10(7) A.cm(-2), comparable or better than copper at similar dimensions. Both the nanotube alignment and failure current density improve with decreasing structure width. In addition, we present a novel Pt nanocluster decoration method that drastically decreases the resistivity of the test structures. Ab initio density functional theory calculations indicate that the increase in conductivity of the nanotubes is caused by an increase in conduction channels close to their Fermi levels due to the platinum nanocluster decoration, with a possible conversion of the semiconducting single-wall carbon nanotubes into metallic ones. These results reflect a huge step toward the proposed replacement of copper-based interconnects with carbon nanotubes at gigascale integration levels.
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Affiliation(s)
- Young Lae Kim
- Department of Electrical & Computer Engineering, Northeastern University, Boston, MA 02115, USA
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Narayanan TN, Suchand Sandeep CS, Shaijumon MM, Ajayan PM, Philip R, Anantharaman MR. The synthesis of high coercivity cobalt-in-carbon nanotube hybrid structures and their optical limiting properties. Nanotechnology 2009; 20:285702. [PMID: 19550014 DOI: 10.1088/0957-4484/20/28/285702] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Magnetic heterostructures with carbon nanotubes having multiple functionalities are fascinating materials which can be manipulated by means of an external magnetic field. In this paper we report our investigations on the synthesis and optical limiting properties of pristine cobalt nanotubes and high coercivity cobalt-in-carbon nanotubes (a new nanosystem where carbon nanotubes are filled with cobalt nanotubes). A general mobility assisted growth mechanism for the formation of one-dimensional nanostructures inside nanopores is verified in the case of carbon nanotubes. The open-aperture z-scan technique is employed for the optical limiting measurements in which nanosecond laser pulses at 532 nm have been used for optical excitation. Compared to the benchmark pristine carbon nanotubes these materials show an enhanced nonlinear optical absorption, and the nonlinear optical parameters calculated from the data show that these materials are efficient optical limiters. To the best of our knowledge this is the first report where the optical limiting properties of metal nanotubes are compared to those of carbon nanotubes.
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Affiliation(s)
- T N Narayanan
- Department of Physics, Cochin University of Science and Technology, Cochin, India
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Abstract
Vertically aligned arrays of multi-wall carbon nanotubes (MWNT) are grown on Inconel 600, a nickel-based super-alloy. Using x-ray photoelectron spectroscopy (XPS) and chemical vapor deposition (CVD) growth of the MWNTs it is shown that a stable oxidation barrier is required for the stabilization of iron on the substrate and subsequent nanotube growth. This evidence for passivation oxide supported growth of MWNTs was then used to grow MWNTs on patterned oxidized substrates in a selective growth furnace. The unique advantage of this patterned growth on Inconel 600 is found to be the chromia passivation layer's electrical conductivity (measured value of 1.08 micro Omega m), creating the opportunity for low resistivity electrodes made from nanotubes. Inconel substrates with 100 microm long aligned MWNTs are demonstrated to exhibit an average resistance value of 2 Omega.
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Affiliation(s)
- J B Bult
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
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36
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Narayanan TN, Mary APR, Shaijumon MM, Ci L, Ajayan PM, Anantharaman MR. On the synthesis and magnetic properties of multiwall carbon nanotube-superparamagnetic iron oxide nanoparticle nanocomposites. Nanotechnology 2009; 20:055607. [PMID: 19417354 DOI: 10.1088/0957-4484/20/5/055607] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Multiwall carbon nanotubes (MWCNTs) possessing an average inner diameter of 150 nm were synthesized by template assisted chemical vapor deposition over an alumina template. Aqueous ferrofluid based on superparamagnetic iron oxide nanoparticles (SPIONs) was prepared by a controlled co-precipitation technique, and this ferrofluid was used to fill the MWCNTs by nanocapillarity. The filling of nanotubes with iron oxide nanoparticles was confirmed by electron microscopy. Selected area electron diffraction indicated the presence of iron oxide and graphitic carbon from MWCNTs. The magnetic phase transition during cooling of the MWCNT-SPION composite was investigated by low temperature magnetization studies and zero field cooled (ZFC) and field cooled experiments. The ZFC curve exhibited a blocking at approximately 110 K. A peculiar ferromagnetic ordering exhibited by the MWCNT-SPION composite above room temperature is because of the ferromagnetic interaction emanating from the clustering of superparamagnetic particles in the constrained volume of an MWCNT. This kind of MWCNT-SPION composite can be envisaged as a good agent for various biomedical applications.
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Affiliation(s)
- T N Narayanan
- Department of Physics, Cochin University of Science and Technology, Cochin-22, Kerala, India
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37
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Abstract
Carbon nanotubes are considered short fibers, and polymer composites with nanotube fillers are always analogues of random, short fiber composites. The real structural carbon fiber composites, on the other hand, always contain carbon fiber reinforcements where fibers run continuously through the composite matrix. With the recent optimization in aligned nanotube growth, samples of nanotubes in macroscopic lengths have become available, and this allows the creation of composites that are similar to the continuous fiber composites with individual nanotubes running continuously through the composite body. This allows the proper utilization of the extreme high modulus and strength predicted for nanotubes in structural composites. Here, we fabricate such continuous nanotube polymer composites with continuous nanotube reinforcements and report that under compressive loadings, the nanotube composites can generate more than an order of magnitude improvement in the longitudinal modulus (up to 3,300%) as well as damping capability (up to 2,100%). It is also observed that composites with a random distribution of nanotubes of same length and similar filler fraction provide three times less effective reinforcement in composites.
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Affiliation(s)
- L Ci
- Department of Mechanical Engineering and Materials Science, Rice University, Houston, Texas 77251, USA
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38
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Abstract
The design of reversible adhesives requires both stickiness and the ability to remain clean from dust and other contaminants. Inspired by gecko feet, we demonstrate the self-cleaning ability of carbon nanotube-based flexible gecko tapes.
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Affiliation(s)
- Sunny Sethi
- Department of Polymer Science, The University of Akron, Akron, Ohio 44325, USA
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Pal SK, Talapatra S, Kar S, Ci L, Vajtai R, Borca-Tasciuc T, Schadler LS, Ajayan PM. Time and temperature dependence of multi-walled carbon nanotube growth on Inconel 600. Nanotechnology 2008; 19:045610. [PMID: 21817516 DOI: 10.1088/0957-4484/19/04/045610] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The growth kinetics of vertically aligned multi-walled carbon nanotubes (MWNTs) on conductive substrates is investigated by synthesizing MWNTs at different growth temperatures and measuring ex situ the length of the nanotubes as a function of growth duration. A typical 'root growth' mechanism (saturation of MWNT lengths with increasing growth duration) was observed. The value of the activation energy (E(a)≈136 ± 5 kJ mol(-1)) of the MWNT growth reaction is suggestive of carbon diffusion through the bulk of the iron catalyst particle versus diffusion on its surface. These findings will help in optimizing MWNT growth on conductive substrates for various applications.
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Affiliation(s)
- S K Pal
- Mechanical Engineering, Rensselaer Polytechnic Institute, Troy, NY-12180, USA
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40
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Zhang Y, Talapatra S, Kar S, Vajtai R, Nayak SK, Ajayan PM. First-principles study of defect-induced magnetism in carbon. Phys Rev Lett 2007; 99:107201. [PMID: 17930406 DOI: 10.1103/physrevlett.99.107201] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2005] [Revised: 02/25/2007] [Indexed: 05/25/2023]
Abstract
We have studied the role of defects on the magnetic properties of carbon materials using first-principles density functional methods. We show that, while the total magnetization decreases both for diamond and graphite with increase in vacancy density, the magnetization decreases more rapidly for graphitic structures. The presence of nitrogen nearby a vacancy is shown to produce larger macroscopic magnetic signals as compared to a standalone carbon vacancy. The results indicate the possibility of tuning magnetization in carbon by controlled defect generation and doping.
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Affiliation(s)
- Y Zhang
- Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180-3590, USA
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Suhr J, Victor P, Ci L, Sreekala S, Zhang X, Nalamasu O, Ajayan PM. Fatigue resistance of aligned carbon nanotube arrays under cyclic compression. Nat Nanotechnol 2007; 2:417-21. [PMID: 18654325 DOI: 10.1038/nnano.2007.186] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Accepted: 05/30/2007] [Indexed: 05/22/2023]
Abstract
Structural components subject to cyclic stress can succumb to fatigue, causing them to fail at stress levels much lower than if they were under static mechanical loading. However, despite extensive research into the mechanical properties of carbon nanotube structures for more than a decade, data on the fatigue behaviour of such devices have never been reported. We show that under repeated high compressive strains, long, vertically aligned multiwalled nanotubes exhibit viscoelastic behaviour similar to that observed in soft-tissue membranes. Under compressive cyclic loading, the mechanical response of the nanotube arrays shows preconditioning, characteristic viscoelasticity-induced hysteresis, nonlinear elasticity and stress relaxation, and large deformations. Furthermore, no fatigue failure is observed at high strain amplitudes up to half a million cycles. This combination of soft-tissue-like behaviour and outstanding fatigue resistance suggests that properly engineered nanotube structures could mimic artificial tissues, and that their good electrical conductivity could lead to their use as compliant electrical contacts in a variety of applications.
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Affiliation(s)
- J Suhr
- Department of Mechanical Engineering, The University of Nevada, Reno, Nevada 89557, USA
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Borca-Tasciuc T, Mazumder M, Son Y, Pal SK, Schadler LS, Ajayan PM. Anisotropic thermal diffusivity characterization of aligned carbon nanotube-polymer composites. J Nanosci Nanotechnol 2007; 7:1581-8. [PMID: 17450929 DOI: 10.1166/jnn.2007.657] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The anisotropic thermal diffusivity of aligned carbon nanotube-polymer composites was determined using a photothermoelectric technique. The composites were obtained by infiltrating poly-dimethyl siloxane (PDMS) in aligned multiwall CNT arrays grown by chemical vapor deposition on silicon substrates. The thermal diffusivities are insensitive to temperature in the range of 180 K-300 K. The thermal diffusivity values across the alignment direction are approximately 2-4 times smaller than along the alignment direction and larger than effective media theory predictions using reported values for the thermal diffusivity of millimeter thick aligned multiwall carbon nanotube arrays. The effective room temperature thermal conductivity of the composite along the carbon nanotube alignment direction is at least 6X larger than the thermal conductivity of the polymer matrix and is in good agreement with the effective media predictions. This work indicates that infiltration of long and aligned carbon nanotube arrays is currently the most efficient method to obtain high thermal conductivity polymer composites.
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Affiliation(s)
- T Borca-Tasciuc
- Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
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43
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Lezec HJ, McMahon JJ, Nalamasu O, Ajayan PM. Submicrometer dimple array based interference color field displays and sensors. Nano Lett 2007; 7:329-33. [PMID: 17297996 DOI: 10.1021/nl062425a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We report a technique for producing bright color fields over extended surfaces, via optical interference, with the capability of producing arbitrary visible colors in areas as small as 100 microm2. Periodic arrays of submicrometer dimples are fabricated on reflective silicon surfaces, and diffraction-induced mutual interference of light reflected from the upper and lower levels of the dimpled surfaces generates color depending on wavelength scaled dimple depth and periodicity. Colors of the entire visible spectrum can be generated by dimple arrays with different dimple depths. The topological permeability of such an open surface readily allows infusion of liquids, with different refractive indices, for color switching and detection. These easy to fabricate, scalable, robust devices, on solid as well as flexible supports, could find a wide range of applications such as cheap high-resolution printable dye/pigment-free displays, reliable index-of-refraction sensors with color readout for liquids, and lab-on-chip liquid flow monitors.
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Affiliation(s)
- H J Lezec
- Thomas J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, California 91125, USA
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44
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Talapatra S, Kar S, Pal SK, Vajtai R, Ci L, Victor P, Shaijumon MM, Kaur S, Nalamasu O, Ajayan PM. Direct growth of aligned carbon nanotubes on bulk metals. Nat Nanotechnol 2006; 1:112-6. [PMID: 18654161 DOI: 10.1038/nnano.2006.56] [Citation(s) in RCA: 153] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2006] [Revised: 08/21/2006] [Accepted: 08/29/2006] [Indexed: 05/20/2023]
Abstract
There are several advantages of growing carbon nanotubes (CNTs) directly on bulk metals, for example in the formation of robust CNT-metal contacts during growth. Usually, aligned CNTs are grown either by using thin catalyst layers predeposited on substrates or through vapour-phase catalyst delivery. The latter method, although flexible, is unsuitable for growing CNTs directly on metallic substrates. Here we report on the growth of aligned multiwalled CNTs on a metallic alloy, Inconel 600 (Inconel), using vapour-phase catalyst delivery. The CNTs are well anchored to the substrate and show excellent electrical contact with it. These CNT-metal structures were then used to fabricate double-layer capacitors and field-emitter devices, which demonstrated improved performance over previously designed CNT structures. Inconel coatings can also be used to grow CNTs on other metallic substrates. This finding overcomes the substrate limitation for nanotube growth which should assist the development of future CNT-related technologies.
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45
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Talapatra S, Kim T, Wei BQ, Kar S, Vajtai R, Sastry GVS, Shima M, Srivastava D, Ajayan PM. Room Temperature Ferromagnetism in Graphitic Nanoclusters. ACTA ACUST UNITED AC 2006. [DOI: 10.1556/nano.1.2006.3.3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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46
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Vafaei S, Borca-Tasciuc T, Podowski MZ, Purkayastha A, Ramanath G, Ajayan PM. Effect of nanoparticles on sessile droplet contact angle. Nanotechnology 2006; 17:2523-2527. [PMID: 21727499 DOI: 10.1088/0957-4484/17/10/014] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
This paper investigates the change in contact angle of droplets of fluid containing dispersed nanoparticles (nanofluid) functionalized with thioglycolic acid molecules as a function of the concentration and size of nanoparticles, and the quality and composition of the substrate material. Bismuth telluride nanoparticles with an average size ranging from 2.5 to 10.4 nm and functionalized with thioglycolic acid groups were grown by a microemulsion method and dispersed in water. Experimental measurements of the contact angle of nanofluid droplets cast on smooth glass and silicon substrates show that the contact angle depends strongly on nanoparticle concentration. Moreover, smaller size nanoparticles lead to larger changes in contact angle at the same mass concentration. These findings contribute to understanding the role of functionalized nanoparticles in surface wettability.
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Affiliation(s)
- S Vafaei
- Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA
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47
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Sun L, Banhart F, Krasheninnikov AV, Rodríguez-Manzo JA, Terrones M, Ajayan PM. Carbon Nanotubes as High-Pressure Cylinders and Nanoextruders. Science 2006; 312:1199-202. [PMID: 16728637 DOI: 10.1126/science.1124594] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Closed-shell carbon nanostructures, such as carbon onions, have been shown to act as self-contracting high-pressure cells under electron irradiation. We report that controlled irradiation of multiwalled carbon nanotubes can cause large pressure buildup within the nanotube cores that can plastically deform, extrude, and break solid materials that are encapsulated inside the core. We further showed by atomistic simulations that the internal pressure inside nanotubes can reach values higher than 40 gigapascals. Nanotubes can thus be used as robust nanoscale jigs for extruding and deforming hard nanomaterials and for modifying their properties, as well as templates for the study of individual nanometer-sized crystals under high pressure.
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Affiliation(s)
- L Sun
- Institut für Physikalische Chemie, Universität Mainz, 55099 Mainz, Germany
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48
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Abstract
The effect of varying the hydrothermal time to synthesize manganese oxide (MnO(2)) nanostructures was investigated along with their influence on structural, morphological, compositional, and electrochemical properties in supercapacitor electrode materials. XRD and TEM studies showed that the MnO(2) prepared in shorter hydrothermal dwell time was a mixture of amorphous and nanocrystalline particles, and there was an evolution of crystallinity of the nanostructures as the dwell time increased from 1 to 18 h. Interestingly, SEM, TEM, and HRTEM revealed a variety of structures ranging from nanostructured surface with a distinct platelike morphology to nanorods depending upon the hydrothermal reaction time employed during the preparation of the manganese oxide: increasing the amount of individual nanorods in the materials prepared with longer hydrothermal reaction time. The surface area of the synthesized nanomaterials varied from 100 to 150 m(2)/g. Electrochemical properties were evaluated using cyclic voltammetry (CV) and galvanostatic charge-discharge studies, and the capacitance values were in the range 72-168 F/g depending upon synthesis conditions. The formation mechanism of the nanorods and their impact on the specific capacitance were discussed in detail.
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Affiliation(s)
- V Subramanian
- Department of Electrical and Computer Engineering and Center for Computation and Technology, Louisiana State University, Baton Rouge, LA 70803, USA
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49
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Talapatra S, Ganesan PG, Kim T, Vajtai R, Huang M, Shima M, Ramanath G, Srivastava D, Deevi SC, Ajayan PM. Irradiation-induced magnetism in carbon nanostructures. Phys Rev Lett 2005; 95:097201. [PMID: 16197243 DOI: 10.1103/physrevlett.95.097201] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2005] [Indexed: 05/04/2023]
Abstract
Nitrogen (15N) and carbon (12C) ion implantations with implant energy of 100 keV for different doses were performed on nanosized diamond (ND) particles. Magnetic measurements on the doped ND show ferromagnetic hysteresis behavior at room temperature. The saturation magnetization (M(s)) in the case of 15N implanted samples was found to be higher compared to the 12C implanted samples for dose sizes greater than 10(14) cm(-2). The role of structural modification or defects along with the carbon-nitrogen (C-N) bonding states for the observed enhanced ferromagnetic ordering in 15N doped samples is explained on the basis of x-ray photoelectron spectroscopy measurements.
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Affiliation(s)
- S Talapatra
- Department of MS & E, Rensselaer Polytechnic Institute, Troy, NY 12180-3590, USA
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50
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Cao A, Talapatra S, Vajtai R, Ajayan PM. Flow-induced planar assembly of parallel carbon nanotubes and crossed nanotube junctions. J Nanosci Nanotechnol 2005; 5:1177-80. [PMID: 16108446 DOI: 10.1166/jnn.2005.140] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We report the in-situ assembly of carbon nanotubes by chemical vapor deposition of hydrocarbon precursor (a solution of ferrocene dissolved in isopropyl alcohol). We utilized the vapor stream inside the reaction chamber to comb carbon nanotubes along the same direction and obtained two-dimensional (planar) assembly of nanotubes with tunable distributions. When the carbon source was flowing at a relatively higher rate of approximately 0.2 ml/min, most of nanotubes were driven along the vapor flow direction during their growth process and formed a thin freestanding mat featured with a parallel arrangement, whereas a lower flowing rate (approximately 0.05 ml/min) only resulted in random spider-web structures consisting of crossed nanotube junctions with a variety of configurations (e.g., "+", "Y", "T" shapes and twists). The measured direction-dependent electrical resistance of these two assemblies was in agreement with respective structures, which was anisotropic for parallel nanotubes and nearly isotropic for random networks. Such large-area planar carbon nanotube arrays with controlled orientation and various junction configurations will facilitate the design and fabrication of electronic and mechanical devices.
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Affiliation(s)
- Anyuan Cao
- Materials Science and Engineering Department Rensselaer Polytechnic Institute, Troy, NY 12180, USA
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