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Muhammed Ajmal C, Cha S, Kim W, Faseela KP, Yang H, Baik S. Invariable resistance of conductive nanocomposite over 30% strain. Sci Adv 2022; 8:eabn3365. [PMID: 35960794 PMCID: PMC9374331 DOI: 10.1126/sciadv.abn3365] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 06/29/2022] [Indexed: 05/25/2023]
Abstract
The dependence of the electrical resistance on materials' geometry determines the performance of conductive nanocomposites. Here, we report the invariable resistance of a conductive nanocomposite over 30% strain. This is enabled by the in situ-generated hierarchically structured silver nanosatellite particles, realizing a short interparticle distance (4.37 nm) in a stretchable silicone rubber matrix. Furthermore, the barrier height is tuned to be negligible by matching the electron affinity of silicone rubber to the work function of silver. The stretching results in the electron flow without additional scattering in the silicone rubber matrix. The transport is changed to quantum tunneling if the barrier height is gradually increased by using different matrix polymers with smaller electron affinities, such as ethyl vinyl acetates and thermoplastic polyurethane. The tunneling current decreases with increasing strain, which is accurately described by the Simmons approximation theory. The tunable transport in nanocomposites provides an advancement in the design of stretchable conductors.
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Affiliation(s)
- C. Muhammed Ajmal
- Center for Nanotubes and Nanostructured Composites, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Seokjae Cha
- School of Mechanical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Wonjoon Kim
- School of Mechanical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - K. P. Faseela
- School of Mechanical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Heejun Yang
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Seunghyun Baik
- Center for Nanotubes and Nanostructured Composites, Sungkyunkwan University, Suwon 16419, Republic of Korea
- School of Mechanical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
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Chung K, Bang J, Thacharon A, Song HY, Kang SH, Jang WS, Dhull N, Thapa D, Ajmal CM, Song B, Lee SG, Wang Z, Jetybayeva A, Hong S, Lee KH, Cho EJ, Baik S, Oh SH, Kim YM, Lee YH, Kim SG, Kim SW. Non-oxidized bare copper nanoparticles with surface excess electrons in air. Nat Nanotechnol 2022; 17:285-291. [PMID: 35145286 PMCID: PMC8930766 DOI: 10.1038/s41565-021-01070-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 12/23/2021] [Indexed: 06/14/2023]
Abstract
Copper (Cu) nanoparticles (NPs) have received extensive interest owing to their advantageous properties compared with their bulk counterparts. Although the natural oxidation of Cu NPs can be alleviated by passivating the surfaces with additional moieties, obtaining non-oxidized bare Cu NPs in air remains challenging. Here we report that bare Cu NPs with surface excess electrons retain their non-oxidized state over several months in ambient air. Cu NPs grown on an electride support with excellent electron transfer ability are encapsulated by the surface-accumulated excess electrons, exhibiting an ultralow work function of ~3.2 eV. Atomic-scale structural and chemical analyses confirm the absence of Cu oxide moiety at the outermost surface of air-exposed bare Cu NPs. Theoretical energetics clarify that the surface-accumulated excess electrons suppress the oxygen adsorption and consequently prohibit the infiltration of oxygen into the Cu lattice, provoking the endothermic reaction for oxidation process. Our results will further stimulate the practical use of metal NPs in versatile applications.
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Affiliation(s)
- Kyungwha Chung
- Department of Energy Science, Sungkyunkwan University, Suwon, Republic of Korea
| | - Joonho Bang
- Department of Energy Science, Sungkyunkwan University, Suwon, Republic of Korea
| | - Athira Thacharon
- Department of Energy Science, Sungkyunkwan University, Suwon, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon, Republic of Korea
| | - Hyun Yong Song
- Department of Energy Science, Sungkyunkwan University, Suwon, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon, Republic of Korea
| | - Se Hwang Kang
- Department of Energy Science, Sungkyunkwan University, Suwon, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon, Republic of Korea
- Research Institute of Industrial Science and Technology, Pohang, Republic of Korea
| | - Woo-Sung Jang
- Department of Energy Science, Sungkyunkwan University, Suwon, Republic of Korea
| | - Neha Dhull
- Department of Energy Science, Sungkyunkwan University, Suwon, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon, Republic of Korea
| | - Dinesh Thapa
- Department of Physics and Astronomy and Center for Computational Sciences, Mississippi State University, Mississippi State, MS, USA
| | - C Muhammed Ajmal
- School of Mechanical Engineering, Sungkyunkwan University, Suwon, Republic of Korea
| | - Bumsub Song
- Department of Energy Science, Sungkyunkwan University, Suwon, Republic of Korea
| | - Sung-Gyu Lee
- Department of Energy Science, Sungkyunkwan University, Suwon, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon, Republic of Korea
| | - Zhen Wang
- Department of Energy Science, Sungkyunkwan University, Suwon, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon, Republic of Korea
| | - Albina Jetybayeva
- Department of Materials Science and Engineering, KAIST, Daejeon, Republic of Korea
| | - Seungbum Hong
- Department of Materials Science and Engineering, KAIST, Daejeon, Republic of Korea
| | - Kyu Hyoung Lee
- Department of Materials Science and Engineering, Yonsei University, Seoul, Republic of Korea
| | - Eun Jin Cho
- Department of Chemistry, Chung-Ang University, Seoul, Republic of Korea
| | - Seunghyun Baik
- School of Mechanical Engineering, Sungkyunkwan University, Suwon, Republic of Korea
| | - Sang Ho Oh
- Department of Energy Science, Sungkyunkwan University, Suwon, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon, Republic of Korea
| | - Young-Min Kim
- Department of Energy Science, Sungkyunkwan University, Suwon, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon, Republic of Korea
| | - Young Hee Lee
- Department of Energy Science, Sungkyunkwan University, Suwon, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon, Republic of Korea
| | - Seong-Gon Kim
- Department of Physics and Astronomy and Center for Computational Sciences, Mississippi State University, Mississippi State, MS, USA.
| | - Sung Wng Kim
- Department of Energy Science, Sungkyunkwan University, Suwon, Republic of Korea.
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon, Republic of Korea.
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Ajmal CM, Bae S, Baik S. A Superior Method for Constructing Electrical Percolation Network of Nanocomposite Fibers: In Situ Thermally Reduced Silver Nanoparticles. Small 2019; 15:e1803255. [PMID: 30515984 DOI: 10.1002/smll.201803255] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 11/15/2018] [Indexed: 06/09/2023]
Abstract
Nanocomposite fibers, composed of conductive nanoparticles and polymer matrix, are crucial for wearable electronics. However, the nanoparticle mixing approach results in aggregation and dispersion problems. A revolutionary synthesis method by premixing silver precursor ions (silver ammonium acetate) with polyvinyl alcohol is reported here. The solvation of ions-prevented aggregation, and uniformly distributed silver nanoparticles (in situ AgNPs, 77 nm) are formed after thermal reduction (155 °C) without using additional reducing or dispersion agents. The conductive fiber is synthesized by the wet spinning technology. After careful optimization, flower-shaped silver nanoparticles (AgNFs, 350-450 nm) are also employed as cofillers. The addition of in situ AgNPs (9.5 vol%) to AgNFs (30 vol%) increases electrical conductivity by 1434% (2090 to 32 064 S cm-1 ) through the efficient construction of percolation networks. The in situ AgNPs provide significantly higher conductivity compared with other secondary nanoparticle fillers. The gaseous byproducts dramatically increase flexibility with a moderate compromise in tensile strength (55 MPa). The particle-free ion-level uniform mixing of silver precursors, followed by in situ reduction, would be a fundamental paradigm shift in nanocomposite synthesis.
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Affiliation(s)
- C Muhammed Ajmal
- Department of Energy Science, Sungkyunkwan University, Suwon, 16419, Korea
| | - Seonghyun Bae
- School of Mechanical Engineering, Sungkyunkwan University, Suwon, 16419, Korea
| | - Seunghyun Baik
- School of Mechanical Engineering, Sungkyunkwan University, Suwon, 16419, Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon, 16419, Korea
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Khan FA, Ajmal CM, Bae S, Seo S, Moon H, Baik S. Silver Nanoflower Decorated Graphene Oxide Sponges for Highly Sensitive Variable Stiffness Stress Sensors. Small 2018; 14:e1800549. [PMID: 29756315 DOI: 10.1002/smll.201800549] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 03/29/2018] [Indexed: 05/25/2023]
Abstract
Soft conductive materials should enable large deformation while keeping high electrical conductivity and elasticity. The graphene oxide (GO)-based sponge is a potential candidate to endow large deformation. However, it typically exhibits low conductivity and elasticity. Here, the highly conductive and elastic sponge composed of GO, flower-shaped silver nanoparticles (AgNFs), and polyimide (GO-AgNF-PI sponge) are demonstrated. The average pore size and porosity are 114 µm and 94.7%, respectively. Ag NFs have thin petals (8-20 nm) protruding out of the surface of a spherical bud (300-350 nm) significantly enhancing the specific surface area (2.83 m2 g-1 ). The electrical conductivity (0.306 S m-1 at 0% strain) of the GO-AgNF-PI sponge is increased by more than an order of magnitude with the addition of Ag NFs. A nearly perfect elasticity is obtained over a wide compressive strain range (0-90%). The strain-dependent, nonlinear variation of Young's modulus of the sponge provides a unique opportunity as a variable stiffness stress sensor that operates over a wide stress range (0-10 kPa) with a high maximum sensitivity (0.572 kPa-1 ). It allows grasping of a soft rose and a hard bottle, with the minimal object deformation, when attached on the finger of a robot gripper.
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Affiliation(s)
- Fakhre Alam Khan
- School of Mechanical Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Korea
| | - C Muhammed Ajmal
- Department of Energy Science, Sungkyunkwan University (SKKU), Suwon, 16419, Korea
| | - Seonghyun Bae
- School of Mechanical Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Korea
| | - Sungwon Seo
- School of Mechanical Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Korea
| | - Hyungpil Moon
- School of Mechanical Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Korea
| | - Seunghyun Baik
- School of Mechanical Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon, 16419, Korea
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Abstract
Surface-enhanced Raman scattering (SERS) has received considerable attention as a noninvasive optical sensing technique with ultrahigh sensitivity. While numerous types of metallic particles have been actively investigated as SERS substrates, the development of new SERS agents with high sensitivity and their reliable characterization are still required. Here we report the preparation and characterization of flower-shaped silver (Ag) nanoparticles that exhibit high-sensitivity single-particle SERS performance. Ag nanoflowers (NFs) with bud sizes in the range 220-620 nm were synthesized by the wet synthesis method. The densely packed nanoscale petals with thicknesses in the range 9-22 nm exhibit a large number of hot spots that significantly enhance their plasmonic activity. A single Ag NF particle (530-620 nm) can detect as little as 10-11 M 4-mercaptobenzoic acid, and thus provides a sensitivity three orders of SERS magnitude greater than that of a spherical Ag nanoparticle. The analytical enhancement factors for single Ag NF particles were found to be as high as 8.0 × 109, providing unprecedented high SERS detectivity at the single particle level. Here we present an unambiguous and systematic assessment of the SERS performances of the Ag NFs and demonstrate that they provide highly sensitive sensing platforms by single SERS particle.
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Affiliation(s)
- Shrawan Roy
- IBS Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon 16419, Republic of Korea. Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
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Abstract
There has been considerable attention paid to highly conductive flexible adhesive (CFA) materials as electrodes and interconnectors for future flexible electronic devices. However, the patterning technology still needs to be developed to construct micro-scale electrodes and circuits. Here we developed the selective laser sintering technology where the pattering and curing were accomplished simultaneously without making additional masks. The CFA was composed of micro-scale Ag flakes, multiwalled carbon nanotubes decorated with Ag nanoparticles, and a nitrile-butadiene-rubber matrix. The Teflon-coated polyethylene terephthalate film was used as a flexible substrate. The width of lines (50-500 μm) and circuit patterns were controlled by the programmable scanning of a focused laser beam (power = 50 mW, scanning speed = 1 mm s-1). The laser irradiation removed solvent and induced effective coalescence among fillers providing a conductivity as high as 25 012 S cm-1. The conductivity stability was excellent under the ambient air and humid environments. The normalized resistance change of the pattern was smaller than 1.2 at the bending radius of 5 mm. The cyclability and adhesion of the laser-sintered line pattern on the substrate was excellent. A flexible circuit was fabricated sequentially for operating light emitting diodes during the bending motion, demonstrating excellent feasibility for practical applications in flexible electronics.
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Affiliation(s)
- Seok Young Ji
- Department of Nano Mechanics, Nanomechanical Systems Research Division, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Yuseong-Gu, Daejeon 305-343, Republic of Korea. Department of Nano-Mechatronics, Korea University of Science and Technology (UST), 217 Gajeong-Ro, Yuseong-Gu, Daejeon 305-333, Republic of Korea
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Soumya T, Muhammed Ajmal C, Bahulayan D. Synthesis of bioactive and fluorescent pyridine-triazole-coumarin peptidomimetics through sequential click-multicomponent reactions. Bioorg Med Chem Lett 2017; 27:450-455. [DOI: 10.1016/j.bmcl.2016.12.044] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 11/30/2016] [Accepted: 12/15/2016] [Indexed: 02/01/2023]
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Ajmal CM, Menamparambath MM, Choi HR, Baik S. Extraordinarily high conductivity of flexible adhesive films by hybrids of silver nanoparticle-nanowires. Nanotechnology 2016; 27:225603. [PMID: 27109551 DOI: 10.1088/0957-4484/27/22/225603] [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: 06/05/2023]
Abstract
Highly conductive flexible adhesive (CFA) film was developed using micro-sized silver flakes (primary fillers), hybrids of silver nanoparticle-nanowires (secondary fillers) and nitrile butadiene rubber. The hybrids of silver nanoparticle-nanowires were synthesized by decorating silver nanowires with silver nanoparticle clusters using bifunctional cysteamine as a linker. The dispersion in ethanol was excellent for several months. Silver nanowires constructed electrical networks between the micro-scale silver flakes. The low-temperature surface sintering of silver nanoparticles enabled effective joining of silver nanowires to silver flakes. The hybrids of silver nanoparticle-nanowires provided a greater maximum conductivity (54 390 S cm(-1)) than pure silver nanowires, pure multiwalled carbon nanotubes, and multiwalled carbon nanotubes decorated with silver nanoparticles in nitrile butadiene rubber matrix. The resistance change was smallest upon bending when the hybrids of silver nanoparticle-nanowires were employed. The adhesion of the film on polyethylene terephthalate substrate was excellent. Light emitting diodes were successfully wired to the CFA circuit patterned by the screen printing method for application demonstration.
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Affiliation(s)
- C Muhammed Ajmal
- Department of Energy Science, Sungkyunkwan University, Suwon, 440-746, Korea
| | | | - Hyouk Ryeol Choi
- School of Mechanical Engineering, Sungkyunkwan University, Suwon, 440-746, Korea
| | - Seunghyun Baik
- School of Mechanical Engineering, Sungkyunkwan University, Suwon, 440-746, Korea
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