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Effect of metal/metal oxide catalysts on graphene fiber for improved NO2 sensing

SENSORS AND ACTUATORS B-CHEMICAL 2021年 344卷 130231-130231页

作者： Eom, Wonsik Jang, Ji-Soo Lee, Sang Hoon Lee, Eunsong Jeong, Woojae Kim, Il-Doo Choi, Seon-Jin Han, Tae Hee Hanyang Univ Dept Organ & Nano Engn Seoul 04763 South Korea Korea Adv Inst Sci & Technol Dept Mat Sci & Engn Daejeon 34141 South Korea Hanyang Univ Human Tech Convergence Program Seoul 04763 South Korea Hanyang Univ Div Mat Sci & Engn Seoul 04763 South Korea Hanyang Univ Inst Nano Sci & Technol Seoul 04763 South Korea

Noble metal/metal-oxide-based hybrid gas sensors exhibit a low operating temperature, remarkable sensitivity, and fast recovery. As additives, noble metals induce a catalytic sensitization effect, which promotes charge transfer from the metal oxide to the analyte molecules, the so-called spillover mechanism. This suggests that metal catalysts can improve gas sensing performance. Herein, for the first time, non-noble metals are introduced on hybrid metal oxide/graphene fibers as sensitizers to fabricate high-performance chemiresistive sensors. The formation of metal components can be effectively controlled by annealing the metal oxide on graphene. Remarkably, compared with the corresponding metal oxide/graphene fiber sensors without metal components, the metal/metal oxide/graphene fiber sensors exhibit over a 16-fold higher response to NO2 gas as well as effective recovery characteristics. Specifically, the Cu/Cu2O/graphene and Ni/NiO/graphene fiber sensors operating at 150 degrees C exhibit sensitivities of 18.90 % and 0.82 %, respectively, for 5 ppm NO2 gas. The proposed strategy to achieve flexible graphene fiber chemiresistors by decorating them with non-noble metal and metal oxide nanoparticles opens a new avenue for realizing high-performance devices, such as photovoltaic devices, photocatalysts, and chemical catalysts.

关键词： Graphene fibers Gas sensors Sensitization Non-noble metals Catalytic deoxidation

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Peeling mechanism of interlocked interface between etched acrylonitrile-butadiene-styrene and electroplated metal layer

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SURFACES AND INTERFACES 2021年 26卷

作者： Seo, Jae Sik Jeon, Ho Tak Han, Tae Hee Hanyang Univ Dept Organ & Nano Engn Seoul 04763 South Korea Hyundai Motor Co Mat Dev Ctr Interior Syst Plast Mat Dev Team Hwaseong 18280 South Korea Hanyang Univ Human Tech Convergence Program Seoul 04763 South Korea Hanyang Univ Res Inst Ind Sci Seoul 04763 South Korea

Electroplating of metals on polymer materials is one of the best decorative processes for achieving low cost and light weight. However, low interfacial adhesion often limits practical utilization due to the potential peel-off behavior of metal layers. The interface between the metal layers and acrylonitrile-butadiene-styrene (ABS) substrate and its peeling mechanism are investigated as a function of etching time. S-a, the arithmetic average roughness of the unit area, and S-dr, the interfacial area ratio, are adopted instead of linear roughness, R-a, to quantify the surface profile. As the etching time increases, both S-a and S(dr )for the etched ABS and corresponding metal side increase. The failure mode changes from adhesive to cohesive as the etching time increases, and the peel-off strength of the electroplated ABS exhibits a dependence on the tensile strength of the substrate. The peeloff strength of the electroplated ABS specimens increases to 8.46 N/cm after 30 min of etching time, but the interface degrades, forming inner voids. The S-dr ratio (S-dr,S- polymer/ S-dr,S-plating) is proposed as a surface parameter to predict the peel-off strength of electroplated ABS and represents a new attempt to quantitatively correlate the interfacial morphology with the adhesion strength.

关键词： Electroplating ABS Etching Adhesion Surface profile

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Photo-Triggered Shape Reconfiguration in Stretchable Reduced Graphene Oxide-Patterned Azobenzene-Functionalized Liquid Crystalline Polymer Networks

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ADVANCED FUNCTIONAL MATERIALS 2021年第31期31卷 2102106-2102106页

作者： Cho, Woongbi Jeon, Jisoo Eom, Wonsik Lee, Jae Gyeong Kim, Dong-Gyun Kim, Yong Seok Han, Tae Hee Wie, Jeong Jae Inha Univ Dept Polymer Sci & Engn 100 Inha Ro Incheon 22212 South Korea Inha Univ Program Environm & Polymer Engn 100 Inha Ro Incheon 22212 South Korea Hanyang Univ Dept Organ & Nano Engn 222 Wangsimmni Ro Seoul 04763 South Korea Hanyang Univ Human Tech Convergence Program 222 Wangsimmni Ro Seoul 04763 South Korea Korea Res Inst Chem Technol Adv Mat Div 141 Gajeong Ro Daejeon 34114 South Korea

In recent years, the "Kirigami" have been exploited to engineer stretchable electronics that exhibit enhanced deformability without sacrificing their mechanical and electrical properties. However, kirigami-inspired engineering is often limited to passive mechanical stretching for 3D shape morphing. To counter this problem, in this study, azobenzene-functionalized liquid crystalline polymer networks (azo-LCNs) are monolithically integrated with patterned reduced graphene oxide (rGO), called azo-LCN/rGO, to achieve on-demand shape reconfiguration in response to external stimuli (UV, NIR, solar rays, and portable light);in addition, the azo-LCN/rGO exhibit highly enhanced mechanical and electrical properties. The cross-sectional area and thickness of rGO patterns are controlled using a masking technique and evaporative self-assembly. By the spatial patterning of rGO, insulating azo-LCNs are converted into electrically conducting structures (381.9 S cm(-1)). The elastic modulus of <2 mu m thick azo-LCN can be tailored in the range of 1.3-6.4 GPa by integration with rGO layers of thickness less than 2 mu m. Upon UV irradiation, azo-LCN/rGO exhibit both for/backward in-plane bending as well as out-of-plane chiral twisting, thus overcoming the typical trade-off relationship between elastic modulus and deformability. Finally, an on-demand contactless shape reconfiguration in azo-LCN/rGO by UV irradiation in conjunction with passive mechanical strain is demonstrated.

关键词： liquid crystalline polymer networks nanocomposites photomechanical actuations reduced graphene oxides stretchable electronics

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Facile Manufacturing of Foldable Micro-Supercapacitors Utilizing Pneumatic Printing in Conjunction with Intense Pulsed White Light

SSRN

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SSRN 2024年

作者： Song, Chiho Hwang, Jeonguk Park, Changyoung Lee, Sujin Hwang, Yeon-Taek Kim, Hak-Sung Bansal, Neetu Salunkhe, Rahul R. Ahn, Heejoon Human-Tech Convergence Program Department of Organic and Nano Engineering Hanyang University 222 Wangsimni-ro Seongdong-gu Seoul04763 Korea Republic of Department of Organic and Nano Engineering Hanyang University 222 Wangsimni-ro Seongdong-gu Seoul04763 Korea Republic of Department of Mechanical Engineering Hanyang University 222 Wangsimni-ro Seongdong-gu Seoul04763 Korea Republic of Department of Physics Indian Institute of Technology Jammu Jammu and Kashmir181221 India Department of Battery Engineering Hanyang University 222 Wangsimni-ro Seongdong-gu Seoul04763 Korea Republic of Institute of Nano Science and Technology Hanyang University 222 Wangsimni-ro Seongdong-gu Seoul04763 Korea Republic of

The rapid development of foldable and rollable displays and electronic devices has aggravated the need for flexible and miniaturized energy-storage devices, such as micro-supercapacitors (MSCs). Existing devices have several shortcomings, such as high cost of materials, high energy consumption, and complicated fabrication methods. This study introduces a straightforward method for fabricating flexible MSCs based on reduced graphene oxide (rGO) and manganese oxide utilizing a printing technique and intense pulsed white light (IPWL) technology. Using this method, asymmetric microelectrodes can be easily printed on a flexible polymeric substrate, and rGO and manganese oxide can be quickly synthesized under atmospheric pressure at room temperature via irradiation with IPWL. An asymmetric hybrid-type structure composed of rGO-based carbon materials and synthesized manganese mono-oxide exhibits an areal capacitance of 5.1 mF cm-2 and an energy density of 3 μWh cm-2 at a power density of 0.1 mW cm-2. The developed flexible MSCs worked well at various radii of curvature, even under the extreme bending condition of 1 mm radius of curvature, demonstrating excellent areal capacitance retention of up to 99.4% even after 10,000 repetitive bending cycles. © 2024, The Authors. All rights reserved.

关键词： Supercapacitor

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Steerable and Agile Light-Fueled Rolling Locomotors by Curvature-Engineered Torsional Torque

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ADVANCED SCIENCE 2023年第30期10卷 e2304715页

作者： Choi, Jun-Chan Jeon, Jisoo Lee, Jae-Won Nauman, Asad Lee, Jae Gyeong Cho, Woongbi Lee, Chanwoo Cho, Young-Min Wie, Jeong Jae Kim, Hak-Rin Kyungpook Natl Univ Sch Elect & Elect Engn Daegu 41566 South Korea Korea Inst Sci & Technol Soft Hybrid Mat Res Ctr Seoul 02792 South Korea Inha Univ Program Environm & Polymer Engn Incheon 22212 South Korea Hanyang Univ Dept Organ & Nano Engn Seoul 04763 South Korea Hanyang Univ Human Tech Convergence Program Seoul 04763 South Korea Kyungpook Natl Univ Sch Elect Engn Daegu 41566 South Korea Hanyang Univ Dept Chem Engn Seoul 04763 South Korea Hanyang Univ Inst Nano Sci & Technol Seoul 04763 South Korea Hanyang Univ Res Inst Ind Sci Seoul 04763 South Korea SUNY Syracuse Michael M Szwarc Polymer Res Inst Coll Environm Sci & Forestry Syracuse NY 13210 USA SUNY Syracuse Dept Chem Engn Coll Enviromental Sci & Forestry Syracuse NY 13210 USA

On-demand photo-steerable amphibious rolling motions are generated by the structural engineering of monolithic soft locomotors. Photo-morphogenesis of azobenzene-functionalized liquid crystal polymer networks (azo-LCNs) is designed from spiral ribbon to helicoid helices, employing a 270 & DEG;super-twisted nematic molecular geometry with aspect ratio variations of azo-LCN strips. Unlike the intermittent and biased rolling of spiral ribbon azo-LCNs with center-of-mass shifting, the axial torsional torque of helicoid azo-LCNs enables continuous and straight rolling at high rotation rates (& AP;720 rpm). Furthermore, center-tapered helicoid structures with wide edges are introduced for effectively accelerating photo-motilities while maintaining directional controllability. Irrespective of surface conditions, the photo-induced rotational torque of center-tapered helicoid azo-LCNs can be transferred to interacting surfaces, as manifested by steep slope climbing and paddle-like swimming multimodal motilities. Finally, the authors demonstrate continuous curvilinear guidance of soft locomotors, bypassing obstacles and reaching desired destinations through real-time on-demand photo-steering.

关键词： amphibious multimodal actuation helical soft robot liquid crystal polymer network on-demand steering photo-mechanical rolling

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Carbon nanotube-reduced graphene oxide fiber with high torsional strength from rheological hierarchy control

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NATURE COMMUNICATIONS 2021年第1期12卷 396-396页

作者： Eom, Wonsik Lee, Eunsong Lee, Sang Hoon Sung, Tae Hyun Clancy, Adam J. Lee, Won Jun Han, Tae Hee Hanyang Univ Dept Organ & Nano Engn Seoul 04763 South Korea Hanyang Univ Dept Elect Engn Seoul 04763 South Korea UCL Dept Chem London WC1H 0AJ England Dankook Univ Dept Fiber Syst Engn Yongin 16890 South Korea Hanyang Univ Human Tech Convergence Program Seoul 04763 South Korea

High torsional strength fibers are of practical interest for applications such as artificial muscles, electric generators, and actuators. Herein, we maximize torsional strength by understanding, measuring, and overcoming rheological thresholds of nanocarbon (nanotube/graphene oxide) dopes. The formed fibers show enhanced structure across multiple length scales, modified hierarchy, and improved mechanical properties. In particular, the torsional properties were examined, with high shear strength (914MPa) attributed to nanotubes but magnified by their structure, intercalating graphene sheets. This design approach has the potential to realize the hierarchical dimensional hybrids, and may also be useful to build the effective network structure of heterogeneous materials. Fibers with high torsional strength are of practical interest for artificial muscles, electric generators, actuators, etc. Here, the authors optimize torsional strength by overcoming rheological thresholds of nanocarbon (nanotube/graphene oxide) dopes.

关键词： Condensed-matter physics Nanoscale materials Soft materials

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Curing Kinetics and Structure-Property Relationship of Moisture-Cured One-Component Polyurethane Adhesives

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EUROPEAN POLYMER JOURNAL 2023年 201卷

作者： Moon, Hojun Park, Jeong Eun Cho, Woongbi Jeon, Jaecheol Wie, Jeong Jae Hanyang Univ Dept Organ & Nano Engn 222 Wangsimni Ro Seoul 04763 South Korea Hanyang Univ Human Tech Convergence Program 222 Wangsimni Ro Seoul 04763 South Korea Hanyang Univ Res Inst Ind Sci 222 Wangsimni Ro Seoul 04763 South Korea Hyundai Motor Co Surface Treatment Mat Dev Team 150 Hyundaiyeonguso Ro Hwaseong Si 18280 Gyeonggi Do South Korea Hanyang Univ Dept Chem Engn 222 Wangsimni Ro Seoul 04763 South Korea Hanyang Univ Inst Nano Sci & Technol 222 Wangsimni Ro Seoul 04763 South Korea Suny Syracuse Dept Chem Engn Coll Environm Sci & Forestry Syracuse NY 13210 USA SUNY Syracuse Michael M Szwarc Polymer Res Inst Coll Environm Sci & Forestry Syracuse NY 13210 USA

Moisture-curable polyurethane (PU) adhesives have been exploited in the automotive industry because of their usability, non-toxicity without the use of volatile organic compounds (VOC), outstanding solvent resistance, and adhesiveness. However, there has been a lack of quantitative and comprehensive analyses related to the chemical and thermomechanical properties of moisture-curable PU adhesives depending on the applied curing conditions. Herein, we systematically investigated the effects of curing conditions, including relative humidities (25, 35, 45, 55, 65, and 75%RH) and curing duration (0, 0.25, 0.5, 1, 2, 3, 4, 5, 6, and 7 days), on the structure-property relationships of moisture-cured PU adhesives. As the relative humidity increased, the chemical reaction of the PU adhesives accelerated, and they exhibited a high crosslinking density and storage modulus. However, even prolonged curing time and higher relative humidity did not lead to a continuous enhancement in the mechanical properties of the PU adhesive. After a sufficient curing time, the storage modulus of the PU adhesive reached saturation, and the PU adhesives cured above 65%RH demonstrated a comparable saturated storage modulus. This structure-property relationship of PU adhesives will provide fundamental understanding and insights for quality control and optimization of processing time in the industry.

关键词： Moisture-curable polyurethane adhesive Curing condition Humidity Structure -property relationship

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Wavelength-selective porphyrin photodiodes via control of Soret- and Q-band absorption

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DYES AND PIGMENTS 2021年 193卷 109531-109531页

作者： Bernardini, Martina Shasa Kim, Juhee Kim, Hyeokjun Song, Minkyu Jang, Woo-Dong Chung, Dae Sung Jung, In Hwan Hanyang Univ Dept Organ & Nano Engn 222 Wangsimni Ro Seoul 04763 South Korea Hanyang Univ Human Tech Convergence Program 222 Wangsimni Ro Seoul 04763 South Korea Kookmin Univ Dept Chem 77 Jeongneung Ro Seoul 02707 South Korea Pohang Univ Sci & Technol POSTECH Dept Chem Engn Pohang 37363 South Korea Yonsei Univ Dept Chem 50 Yonsei Ro Seoul 03722 South Korea

Porphyrin-based photodiode materials have mainly been targeted to achieve panchromatic absorption by maximizing the Soret- and Q-band absorption;however, they have rarely been studied with the purpose to make them wavelength-selective in photodetecting devices. In this study, we synthesized a wavelength-selective porphyrin material, PZn-FL, via Sonogashira coupling between an ethyne pi-linked porphyrin core (PZn) and four fluorene (FL) moieties. The synthesized PZn-FL material showed a narrow full-width-at-half-maximum (FWHM) of 75 nm in the blue absorption region. The Q-band absorption of PZn-FL was significantly suppressed in organic photodiodes (OPDs), resulting in a blue-selective specific detectivity spectrum with a FWHM of 75 nm and a noise equivalent power of 2.86 x 10-12 W/Hz0.5. The planar backbone structure of PZn-FL was beneficial to increase charge transport and reduce bimolecular recombination, and the vertically oriented alkyl side chains of the PZn backbone contributed to prevent severe intermolecular aggregation and maintain a narrow absorption in film state.

关键词： Porphyrins Photodetectors Wavelength selectivity Photodiodes Detectivity

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Directed Regeneration of Osteochondral Tissue by Hierarchical Assembly of Spatially Organized Composite Spheroids

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ADVANCED SCIENCE 2022年第3期9卷 e2103525页

作者： Lee, Jinkyu Lee, Seoyun Huh, Seung Jae Kang, Byung-Jae Shin, Heungsoo Hanyang Univ Inst Bioengn & Biopharmaceut Res Dept Bioengn 222 Wangsimni Ro Seoul 04763 South Korea Hanyang Univ BK21 FOUR Human Tech Convergence Program 222 Wangsimni Ro Seoul 04763 South Korea Seoul Natl Univ Dept Vet Clin Sci Coll Vet Med & Res Inst Vet SciBK21 FOUR Future Vet Med Leading Edu 1 Gwanak Ro Seoul 08826 South Korea Hanyang Univ BK21 FOUR Educ & Res Grp Biopharmaceut Innovat Le 222 Wangsimni Ro Seoul 04763 South Korea Hanyang Univ Inst Nano Sci & Technol 222 Wangsimni Ro Seoul 04763 South Korea

The use of engineered scaffolds or stem cells is investigated widely in the repair of injured musculoskeletal tissue. However, the combined regeneration of hierarchical osteochondral tissue remains a challenge due to delamination between cartilage and subchondral bone or difficulty in spatial control over differentiation of transplanted stem cells. Here, two types of composite spheroids are prepared using adipose-derived stem cells (hADSCs) and nanofibers coated with either transforming growth factor-beta 3 or bone morphogenetic growth factor-2 for chondrogenesis or osteogenesis, respectively. Each type of spheroid is then cultured within a 3D-printed microchamber in a spatially arranged manner to recapitulate the bilayer structure of osteochondral tissue. The presence of inductive factors regionally modulates in vitro chondrogenic or osteogenic differentiation of hADSCs within the biphasic construct without dedifferentiation. Furthermore, hADSCs from each spheroid proliferate and sprout and successfully connect the two layers mimicking the osteochondral interface without apertures. In vivo transplantation of the biphasic construct onto a femoral trochlear groove defect in rabbit knee joint results in 21.2 +/- 2.8% subchondral bone volume/total volume and a cartilage score of 25.0 +/- 3.7. The present approach can be an effective therapeutic platform to engineer complex tissue.

关键词： 3D printing composite spheroid microchamber osteochondral tissue regeneration tissue engineering

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Spatially Selective Ultraprecision Polishing and Cleaning by Collective Behavior of Micro Spinbots

SMALL STRUCTURES

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SMALL STRUCTURES 2024年第11期5卷

作者： Je, Hyeongmin Won, Sukyoung Wie, Jeong Jae Kim, Sanha Korea Adv Inst Sci & Technol Dept Mech Engn 291 Daehak Ro Daejeon 34141 South Korea Hanyang Univ Dept Organ & Nano Engn 222 Wangsimni Ro Seoul 04763 South Korea Hanyang Univ Res Inst Ind Sci 222 Wangsimni Ro Seoul 04763 South Korea Hanyang Univ Human Tech Convergence Program 222 Wangsimni Ro Seoul 04763 South Korea Hanyang Univ Dept Chem Engn 222 Wangsimni Ro Seoul 04763 South Korea Hanyang Univ Inst Nano Sci & Technol 222 Wangsimni Ro Seoul 04763 South Korea SUNY Syracuse Coll Environm Sci & Forestry Dept Chem Engn 1 Forestry Dr Syracuse NY 13210 USA SUNY Syracuse Michael M Szwarc Polymer Res Inst Coll Environm Sci & Forestry 1 Forestry Dr Syracuse NY 13210 USA

Untethered magnetic actuation is an attractive technique for controlling a batch of micrometer-sized soft robots. Recent advancements have enabled each robot to follow its path independently using a single magnetic device. However, applications of magnetic soft microrobots are mostly biased toward the biomedical field. In this study, thermoplastic polyurethane-Fe3O4 nanocomposite soft spinning microrobots, that is, spinbots that actuate on a tabletop magnetic stirrer, were utilized as innovative precision manufacturing tools for spatially selective precision polishing and cleaning. The pivot motion of the revolving spinbots, which involves repetitive sweeping during rotation cycles, is explored. This sweeping action physically removes nanometer-sized surface contaminants from the workpiece, achieving a cleaning efficiency of 99.6%. Multiple spinbots, up to 42 in total, simultaneously operated along their own orbital pathways on three vertically stacked wafers, thereby demonstrating an unprecedented cleaning method. In addition, the spinbots precisely removed materials from the workpiece using a three-body abrasion mechanism. Furthermore, the spinbots contributed to precise material removal, resulting in remarkable surface polishing (R a approximate to 1.8 nm). This novel polishing system, which uses the collective behavior of multiple spinbots on a tabletop magnetic stirrer, is 1000-fold lighter than current state-of-the-art equipment aimed at achieving similar levels of fine finishing. Polyurethane-Fe3O4 nanocomposite microrobots, called spinbots, are utilized for precise polishing and cleaning. Multiple microrobots pivot along their trajectories which can sweep to remove nanometer-sized surface contaminants, achieve 99.6% cleaning efficiency, or polish a copper with a fine surface of R a approximate to 1.8 nm. More than 40 spinbots can operate simultaneously on vertically stacked wafers and are spatially restricted when necessary. image (c) 2024 WILEY-VCH GmbH

关键词： cleaning magnetic actuation microrobots polishing untethered miniaturized robots

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