1,721,030 research outputs found
Enhancing the Strength, Toughness, and Electrical Conductivity of Twist-Spun Carbon Nanotube Yarns by π Bridging
No full textSupplementary material is available on publisher's website. Use the DOI link below.Due to copyright restrictions and/or publisher's policy full text access from Treasures at UT Dallas is limited to current UTD affiliates (use the provided Link to Article).The weak interfacial interactions between carbon nanotube (CNT) always results in low stress load transfer efficiency in CNT yarns, herein we fabricated strong, highly conducting CNT yarns at room temperature using molecules having aromatic end groups, π bridging neighboring CNTs. The resulting CNT yarns have high tensile strength with 1697 ± 24 MPa, toughness with 18.6 ± 1.6 MJ/m³, and electrical conductivity with 656.2 S/cm, which are 3.9, 2.5, and 3.5 times, respectively, as high as that of the neat CNT yarn. The specific tensile strength of the resulting CNT yarn is higher than that for previously reported CNT yarns fabricated at room temperature, even that for some CNT yarns fabricated using corossive environments or extreme temperature. This π bridging strategy provides a promising avenue for fabricating high performance CNT yarns under ambient conditions. ©2019 Elsevier LtdExcellent Young Scientist Foundation of NSFC (51522301); the National Natural Science Foundation of China (21875010, 21273017, 51103004); the Program for New Century Excellent Talents in University (NCET-12-0034); the Fok Ying Tong Education Foundation (141045); the 111 Project (B14009); the Aeronautical Science Foundation of China (20145251035, 2015ZF21009); State Key Laboratory of Organic–Inorganic Composites, Beijing University of Chemical Technology (oic-201701007); the State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University (LK1710); the Fundamental Research Funds for the Central Universities (YWF-16-BJ-J-09, YWF-17-BJ-J-33, YWF-18-BJ-J-13); the Academic Excellence Foundation of BUAA (20170666); NSF Award 1636306.School of Natural Sciences and MathematicsAlan G. MacDiarmid NanoTech Institut
Highly Stretchable Hybrid Nanomembrane Supercapacitors
No full textIncludes supplementary materialSupercapacitors that are lightweight, mechanically deformable (stretchable, flexible) and electrochemically stable have potential for various applications like portable, wearable, and implantable electronics. Here we demonstrate a stretchable and high-performing hybrid nanomembrane supercapacitor. The hybrid nanomembrane is prepared by vapour phase polymerization (VPP) based nanoscopic PEDOT coating on carbon nanotube sheets (CNS) transferred onto an elastomeric substrate to form a wavy structure. The resulting wavy structured hybrid nanomembrane based supercapacitor exhibits high electrochemical performance and mechanical stretchability, simultaneously. The high specific capacitances and energy density (82 F g⁻¹, 11 mF cm⁻², and 7.28 W h kg⁻¹ at 0% strain) are retained under large mechanical deformation (77 F g⁻¹ and 6.87 W h kg⁻¹ at a biaxial strain of 600%). Moreover, there is only <1% degradation of capacitance ratio after 1000 cycles stretching/releasing and bending/unbending. This high mechanical cyclic stability is shown even during stretching/releasing and bending/unbending measured by dynamic cyclic voltammetry (CV). These results suggest that our supercapacitor is valuable in a wide range of applications that require it to be electrochemically stable under large mechanical deformation, such as strain sensors, wearable electronics and biomedical devices.This work was supported by the Creative Research Initiative Center for Self-powered Actuation and the Korea-US Air Force Cooperation Program Grant No. 2013K1A3A1A32035592 in Korea. In the USA, Air Force Office of Scientific Research grants FA9550-15-1- 0089 and AOARD-FA2386-13-4119, NASA grants NNX14CS09P and NNX15CS05C, and the Robert A. Welch Foundation grant AT-0029
A Multiscale Model to Study the Enhancement in the Compressive Strength of Multi-Walled CNT Sheet Overwrapped Carbon Fiber Composites
No full textDue to copyright restrictions full text access from Treasures at UT Dallas is restricted to current UTD affiliates (use the provided Link to Article).The high tensile strength of polymer matrix composites is derived primarily from the high strength of the carbon fibers embedded in the polymer matrix. However, their compressive strength is generally much lower due to the fact that under compression, the fibers tend to fail through micro-buckling well before compressive fracture occurs. In this work, we consider multi-walled carbon nanotube (MWNT) sheets wrapped around carbon fiber at room temperature to improve fiber/matrix interfacial properties which, in turn, influences compressive strength of the composite. To investigate the effect of the wrapping of MWNT sheet on composite strength, Molecular Dynamics simulations were performed on an atomistic model of the interface region between the epoxy, carbon fiber and the scrolled MWNT sheets. The compressive strength of the unidirectional composite was computed using a novel hierarchical multi-scale model comprising of the rule of mixtures at the microscale, and the modified Argon's formula for composites at the macroscale. Model predictions were benchmarked through comparison with experimental data for different volume fractions of MWNT sheet. ©2019 Elsevier LtdThis research was supported by the Low Density Materials Program at AFOSR, Grant No. FA9550-14-1-0227 and NSF CMMI-1636308.School of Natural Sciences and MathematicsErik Jonsson School of Engineering and Computer ScienceAlan G. MacDiarmid NanoTech Institut
Biscrolled Carbon Nanotube Yarn Structured Silver-Zinc Battery
Full text linkFlexible yarn- or fiber-based energy storing devices are attractive because of their small dimension, light weight, and suitability for integration into woven or textile application. Some Li-ion based yarn or fiber batteries were developed due to their performance advantages, realizing highly performing and practically safe wearable battery still remains a challenge. Here, high performance and safe yarn-based battery is demonstrated by embedding active materials into inner structure of yarn and using water based electrolyte. Thanks to biscrolling method, loading level of silver and zinc in yarn electrodes increased up to 99 wt%. Our high loaded Silver and Zinc yarn electrodes enables high linear capacity in liquid electrolyte (0.285 mAh/cm) and solid electrolyte (0.276 mAh/cm), which are significantly higher than previously reported fiber batteries. In additions, due to PVA-KOH based aqueous electrolyte, our yarn battery system is inflammable, non-explosive and safe. Consequently, these high-capacities enable our Silver-Zinc aqueous yarn battery to be applicable to the energy source of portable and wearable electronics like an electric watch. © 2018, The Author(s).1
Orthogonal Pattern of Spinnable Multiwall Carbon Nanotubes for Electromagnetic Interference Shielding Effectiveness
No full textDue to copyright restrictions and/or publisher's policy full text access from Treasures at UT Dallas is limited to current UTD affiliates (use the provided Link to Article).The need for thin and lightweight electromagnetic interference shielding materials is rapidly increasing in several industries, such as aerospace and telecommunication. This research finds that a shielding material, which is developed by the orthogonal pattern of spinnable multiwall carbon nanotubes (MWNTs), is ultra-light weight, thin, and has a high shielding effectiveness (SE). An orthogonal pattern, generated by just alignment of the spinnable MWNTs without adding any support materials such as polymers, ceramics, and magnets demonstrates that it is possible to efficiently attenuate electromagnetic interference (EMI) in the X-band frequency range (8.2–12.4 GHz). EMI SE in the developed shielding material is about 19.2 dB with a specific shielding effectiveness (SSE)/t (thickness) value of 73,633 dB cm² g⁻¹ at a thickness of about 4.48 μm. In addition, absorption effectiveness in this shielding material is as high as 96.3%, which provides excellent ability to reduce the secondary damage by reflection. ©2019 Elsevier LtdNational Research Foundation of Korea and the National Research Foundation (Grant No. 2016R1C1B2012340) of the Ministry of Science; Air Force Office of Scientific Research grant FA9550-15-1-0089 I; Robert A. Welch Foundation grant AT-0029.School of Natural Sciences and MathematicsAlan G. MacDiarmid NanoTech Institut
Terahertz Surface Plasmon Polaritons on Freestanding Multi-Walled Carbon Nanotube Aerogel Sheets
No full textWe demonstrate that multi-walled carbon nanotubes (MWCNTs) are capable of supporting surface plasmon-polaritons (SPPs) at terahertz (THz) frequencies. To achieve this, we fabricated sub-100 μm-thick freestanding and highly oriented multi-walled carbon nanotube (MWCNT) aerogel sheets. Utilizing terahertz time-domain spectroscopy, we measured the complex index of refraction of the sheets for two orthogonal nanotube orientations. We found that the MWCNT sheets exhibit highly anisotropic THz polarization behavior. Based on the extracted dielectric properties of the medium, which show that it exhibits metallic behavior in the THz spectral range, we investigated the existence and propagation of SPPs by studying the resonantly enhanced transmission through periodic MWCNT hole arrays. We found that carbon nanotubes support SPP excitations that propagate along the tubes, but highly suppress these surface waves in the direction perpendicular to the nanotubes.This work was supported by the NSF MRSEC program at the University of Utah under grant # DMR 1121252
Three-Dimensionally Ordered Macro-/Mesoporous Ni as a Highly Efficient Electrocatalyst for the Hydrogen Evolution Reaction
No full textThree-dimensionally (3D) ordered macro-/mesoporous (3DOM/m) Ni is fabricated by the chemical reduction deposition method using lyotropic liquid crystals (LLC) to template the mesostructure within the regular voids of a colloidal crystal (opal). The thereby achieved structural advantages of combining well-ordered bicontinuous mesopores with 3D interconnected periodic macropores, such as abundant exposed catalytically active sites, efficient mass transport, and high electrical conductivity, make this non-noble metal structure an excellent hydrogen evolution reaction (HER) electrocatalyst. The 3DOM/m Ni exhibits a low onset overpotential of 63 mV (vs. RHE) and a small Tafel slope of 52 mV per decade, as well as a long-term durability in alkaline medium. These distinct features of the 3DOM/m Ni render it a promising alternative to Pt-based HER electrocatalysts.Support provided by the National Natural Science Foundation of China (51172014 and 20971012), and the National 973 Program of China (2009CB219903)
Biothermal Sensing of a Torsional Artificial Muscle
No full textSupplementary material availableBiomolecule responsive materials have been studied intensively for use in biomedical applications as smart systems because of their unique property of responding to specific biomolecules under mild conditions. However, these materials have some challenging drawbacks that limit further practical application, including their speed of response and mechanical properties, because most are based on hydrogels. Here, we present a fast, mechanically robust biscrolled twist-spun carbon nanotube yarn as a torsional artificial muscle through entrapping an enzyme linked to a thermally sensitive hydrogel, poly(N-isopropylacrylamide), utilizing the exothermic catalytic reaction of the enzyme. The induced rotation reached an equilibrated angle in less than 2 min under mild temperature conditions (25-37 ⁰C) while maintaining the mechanical properties originating from the carbon nanotubes. This biothermal sensing of a torsional artificial muscle offers a versatile platform for the recognition of various types of biomolecules by replacing the enzyme, because an exothermic reaction is a general property accompanying a biochemical transformation.Supported by the Creative Research Initiative Center for Self-powered Actuation and the Korea–US Air Force Cooperation Program (grant #2013K1A3A1A32035592), Air Force Office of Scientific Research (grants #FA9550-15-1-0089, #AOARD-FA2386-13-4119), NASA (grants #NNX14CS09P, #NNX15CS05C), Robert A. Welch Foundation (grant #AT-0029
Probe Sensor Using Nanostructured Multi-Walled Carbon Nanotube Yarn for Selective and Sensitive Detection of Dopamine
No full textThe demands for electrochemical sensor materials with high strength and durability in physiological conditions continue to grow and novel approaches are being enabled by the advent of new electromaterials and novel fabrication technologies. Herein, we demonstrate a probe-style electrochemical sensor using highly flexible and conductive multi-walled carbon nanotubes (MWNT) yarns. The MWNT yarn-based sensors can be fabricated onto micro Pt-wire with a controlled diameter varying from 100 to 300 µm, and then further modified with Nafion via a dip-coating approach. The fabricated micro-sized sensors were characterized by electron microscopy, Raman, FTIR, electrical, and electrochemical measurements. For the first time, the MWNT/Nafion yarn-based probe sensors have been assembled and assessed for high-performance dopamine sensing, showing a significant improvement in both sensitivity and selectivity in dopamine detection in presence of ascorbic acid and uric acid. It offers the potential to be further developed as implantable probe sensors
Conductive Functional Biscrolled Polymer and Carbon Nanotube Yarns
No full textBiscrolling aligned electrospun fiber (AEF) sheets and carbon nanotube (CNT) sheets were fabricated for conductive, functional yarns by a versatile dry composite method. Our biscrolling (twist-based spinning) method is based on spinnable polymer fiber sheets and spinnable CNT sheets unlike the previous biscrolling technique using unspinnable nanopowders and spinnable CNT sheets. The CNT sheet in composite yarns acted as effective electrical wires forming dual Archimedean multilayer rolled-up nanostructures. The weight percent of the electrospun polymer fibers in the composite yarns was over 98%, and the electrical conductivity values of the composite yarns was 3 orders higher than those of other non-conducting polymer/CNT composite fibers which were electrospun from polymer solutions containing similar loading of CNTs. We also demonstrate that biscrolled yarns having various structures can be fabricated from spinnable AEF sheets and spinnable CNT sheets.Funded in part by Technology Development Program (10038599), and the MSIP-US Air Force Cooperation Program (2013K1A3A1A32035592) in Korea and Air Force Grant AOARD-10-4067, Air Force Office of Scientific Research grant FA9550-09-1-0537, and Robert A. Welch Foundation grant AT-0029 in the USA
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