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Amine functionalization on thermal and mechanical behaviors of graphite nanofibers-loaded epoxy composites

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Journal of Materials Science & Technology 2023年第20期151卷 80-88页

作者： Seong-Hwang Kim Sang-jin park Seul-Yi Lee soo-jin park Department of Chemistry Inha University100 InharoIncheon 22212the Republic of Korea

With the growing demand for faster and more powerful computing,effective heat dissipation is essential to ensure the longevity,reliability,and high performance of electronic *** the field of modern electronic packaging materials,there is a great need for graphitic material-loaded polymeric composites(GPCs)with excellent thermal ***,the enhancement efficiency of GPCs is hindered by the agglomeration of fillers and the interfacial thermal resistance caused by the lack of continuous thermally conductive pathways between the filler and *** the interfaces between filler and matrix is of great importance in optimizing the performances of ***,we fabricated graphite nanofibers(GNF)-loaded nanocomposites using acid-functionalized GNF(AGNF)and acidtetraethylenepentamine-functionalized(TGNF)as a filler and epoxy resin as a matrix with different GNF loading contents to explore the interfacial properties of the *** optimal GNF loading for AGNF was 0.5 wt.%,while the TGNF showed 0.75 wt.%.The highest thermal conductivity(0.51 W m^(−1) K^(−1))and fracture toughness(25.8 MPa m^(1/2))values were found in the TGNF-loaded nanocomposites with a fraction of 0.75 wt.%,representing enhancements of∼145%and∼400%,respectively,compared to those of neat *** experimental data presented herein demonstrate that the interfacial properties play a significant role in enhancing the thermal and mechanical performances of the *** present approach is expected to serve as a valuable tool in the design of conductive polymeric nanocomposites for further practical applications,such as thermal interface materials and packaging of high-power electric devices.

关键词： Graphite nanofiber Nanocomposites Interfacial interaction Thermal conductivity Fracture resistance

Biomass-derived bifunctional electrocatalysts for oxygen reduction and evolution reaction: A review

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Journal of Energy Chemistry 2022年第2期31卷 149-172页

作者： Satpal Singh Sekhon Jaeyoung Lee jin-soo park Future Environment and Energy Research Institute Sangmyung UniversityCheonan 31066Republic of Korea Department of Physics Guru Nanak Dev UniversityAmritsar 143005India Ertl Center for Electrochemistry and Catalysis Gwangju Institute of Science and Technology123 Cheomdangwagi-roBuk-guGwangju 61005Republic of Korea Department of Green Chemical Engineering College of EngineeringSangmyung UniversityCheonan 31066Republic of Korea

Oxygen electrode catalysts are important as inter-conversion of O_(2) and H_(2)O is crucial for energy ***,the sluggish kinetics of oxygen reduction and evolution reactions(ORR and OER)are a hindrance to their scalable production,whereas scarce and costly Pt and Ir/Ru-based catalysts with the highest electrocatalytic activity are commercially *** good ORR catalysts are not always efficient for OER and vice versa,so bifunctional catalysts on which OER and ORR occurs on the same electrode are very *** catalysts based on heteroatom-doped carbon nanomaterials,though showed good electrocatalytic activity yet their high cost and complex synthesis is not viable for scalable *** overcome these drawbacks,biomass-derived heteroatom-doped porous carbons have recently emerged as low-cost,earth-abundant,renewable and sustainable environment-friendly materials for bifunctional oxygen *** tunable morphology,mesoporous structure and high concentration of catalytic active sites of these materials due to heteroatom(N)-doping could further enhance their ORR and OER activity,along with tolerance to methanol crossover and good ***,biomassderived heteroatom-doped porous carbons with large surface area,rich edge defects,numerous micropores and thin 2 D nanoarchitecture could be suitable as efficient bifunctional oxygen *** the present article,synthesis,N-doping,ORR/OER mechanism and electrocatalytic performance of biomassderived bifunctional catalysts has been *** selected biomass(chitin,eggs,euonymus japonicas,tobacco,lysine and plant residue)except wood,act as both C and N precursor,resulting in N selfdoping of porous carbons that avoids the use of toxic chemicals,thus making the synthesis a facile and environment-friendly green *** synthetic strategy could be further optimized to develop future biomass-based N self-doped porous carbons as metal-free high performance bifunctional oxy

关键词： Bifunctional catalysts Biomass ORR OER N-doping Porous carbons

Steam activation of Fe-N-C catalyst for advanced power performance of alkaline hydrazine fuel cells

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Journal of Energy Chemistry 2022年第1期31卷 276-285,I0008页

作者： sooan Bae Jihyeon park Yuna Hwang jin-soo park Jaeyoung Lee Beomgyun Jeong Research Center for Materials Analysis Korea Basic Science Institute169-14&Gwahak-roDaejeon 34133Republic of Korea School of Earth Sciences and Environmental Engineering Gwangju Institute of Science and Technology123 Cheomdangwagi-ro.Buk-guGwangju 61005Republic of Korea Department of Green Chemical Engineering Sangmyung University31 Sangmyungdae-gilDongnam-gu.CheonanChungnam Province 31066Republic of Korea Ertl Center for Electrochemistry and Catalysis Gwangju Institute of Science and Technology123 Cheomdangwagi-roBuk-giiGwangju 61005Republic of Korea

Alkaline hydrazine liquid fuel cells(AHFC) have been highlighted in terms of high power performance with non-precious metal *** Fe-N-C is a promising non-Pt electrocatalyst for oxygen reduction reaction(ORR),the surface density of the active site is very low and the catalyst layer should be thick to acquire the necessary number of catalytic active *** this thick catalyst layer,it is important to have an optimum pore structure for effective reactant conveyance to active sites and an interface structure for faster charge ***,we prepare a Fe-N-C catalyst with magnetite particles and hierarchical pore structure by steam *** steam activation process significantly improves the power performance of the AHFC as indicated by the lower IR and activation voltage *** on a systematic characterization,we found that hierarchical pore structures improve the catalyst utilization efficiency of the AHFCs,and magnetite nanoparticles act as surface modifiers to reduce the interracial resistance between the electrode and the ion-exchange membrane.

关键词： Alkaline hydrazine fuel cell Oxygen reduction reaction Electrocatalyst Steam activation Ohmic loss Interfacial resistance Surface modifier

Highly Flexible Fabrics/Epoxy Composites with Hybrid Carbon Nanofillers for Absorption-Dominated Electromagnetic Interference Shielding

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Nano-Micro Letters 2022年第11期14卷 307-323页

作者： Jong-Hoon Lee Yoon-Sub Kim Hea-jin Ru Seul-Yi Lee soo-jin park Department of Chemistry Inha University100 InharoIncheon 22212Korea Korea Architecture Safety Testing and Research Institute(KASTI) 88 Gasan Digital 1-roSeoul 08590Korea

Epoxy-based nano-composites can be ideal electromagnetic interference(EMI)-shielding materials owing to their lightness,chemical inertness,and mechanical ***,poor conductivity and brittleness of the epoxy resin are challenges for fast-growing portable and flexible EMI-shielding applications,such as smart wristband,medical cloth,aerospace,and military *** this study,we explored hybrid nanofillers of single-walled carbon nanotubes(SWCNT)/reduced graphene oxide(rGO)as conductive inks and polyester fabrics(PFs)as a substrate for flexible EMI-shielding *** highest electrical conductivity and fracture toughness of the SWCNT/rGO/PF/epoxy composites were 30.2 S m^(−1)and 38.5 MPa m^(1/2),which are~270 and 65%enhancement over those of the composites without SWCNTs,*** mechanical durability was demonstrated by stable electrical conductivity retention during 1000 cycles of bending *** EMI-shielding effectiveness of~41 dB in the X-band frequency of 8.2-12.4 GHz with a thickness of 0.6 mm was obtained with an EM absorption-dominant behavior over a 0.7 absorption *** results are attributed to the hierarchical architecture of the macroscale PF skeleton and nanoscale SWCNT/rGO networks,leading to superior EMI-shielding *** believe that this approach provides highly flexible and robust EMI-shielding composites for next-generation wearable electronic devices.

关键词： Conductive polymer composites Fracture toughness Flexible composites Absorption-dominated electromagnetic interference shielding

Dual-frequency piezoelectric micromachined ultrasound transducer based on polarization switching in ferroelectric thin films

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Microsystems & Nanoengineering 2023年第5期9卷 233-243页

作者： jin soo park soo Young Jung Dong Hun Kim Jung Ho park Ho Won Jang Tae Geun Kim Seung-Hyub Baek Byung Chul Lee Bionics Research Center Korea Institute of Science and TechnologySeoul 02792Republic of Korea Department of Electrical Engineering Korea UniversitySeoul 02841Republic of Korea Center for Electronic Materials Korea Institute of Science and TechnologySeoul 02792Republic of Korea Department of Material Science and Engineering Seoul National UniversitySeoul 08826Republic of Korea Division of Bio-Medical Science and Technology KIST SchoolUniversity of Science and Technology(UST)Seoul 02792Republic of Korea KHU-KIST Department of Converging Science and Technology Kyung Hee UniversitySeoul 02447Republic of Korea

Due to its additional frequency response,dual-frequency ultrasound has advantages over conventional ultrasound,which operates at a specific frequency ***,a tunable frequency from a single transducer enables sonographers to achieve ultrasound images with a large detection area and high *** facilitates the availability of more advanced techniques that simultaneously require low-and high-frequency ultrasounds,such as harmonic imaging and image-guided *** this study,we present a novel method for dual-frequency ultrasound generation from a ferroelectric piezoelectric micromachined ultrasound transducer(PMUT).Uniformly designed transducer arrays can be used for both deep low-resolution imaging and shallow high-resolution *** switch the ultrasound frequency,the only requirement is to tune a DC bias to control the polarization state of the ferroelectric *** vibration of the PMUT membrane strongly depends on the polarization state,producing low-and high-frequency ultrasounds from a single excitation *** strategy for dual-frequency ultrasounds meets the requirement for either multielectrode configurations or heterodesigned elements,which are integrated into an ***,this technique significantly reduces the design complexity of transducer arrays and their associated driving circuits.

关键词： piezoelectric ferroelectric enable

A Review on Interface Engineering of MXenes for Perovskite Solar Cells

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Nano-Micro Letters 2023年第8期15卷 270-308页

作者： Srikanta Palei G.Murali Choong‑Hee Kim Insik In Seul‑Yi Lee soo‑jin park Department of Chemistry Inha University100 InharoIncheon 22212South Korea Department of Polymer Science and Engineering Department of IT‑Energy Convergence(BK21 Four)Chemical Industry InstituteKorea National University of TransportationChungju 27469South Korea

With an excellent power conversion efficiency of 25.7%,closer to the Shockley–Queisser limit,perovskite solar cells(PSCs)have become a strong candidate for a next-generation energy ***,the lack of stability and reliability in PSCs remained challenging for ***,such as interfacial and structural engineering,have a more critical influence on enhanced ***,two-dimensional materials,have emerged as promising materials in solar cell applications due to their metallic electrical conductivity,high carrier mobility,excellent optical transparency,wide tunable work function,and superior mechanical *** to different choices of transition elements and surface-terminating functional groups,MXenes possess the feature of tuning the work function,which is an essential metric for band energy alignment between the absorber layer and the charge transport layers for charge carrier extraction and collection in ***,adopting MXenes to their respective components helps reduce the interfacial recombination resistance and provides smooth charge transfer paths,leading to enhanced conductivity and operational stability of *** review paper aims to provide an overview of the applications of MXenes as components,classified according to their roles as additives(into the perovskite absorber layer,charge transport layers,and electrodes)and themselves alone or as interfacial layers,and their significant importance in PSCs in terms of device performance and ***,we discuss the present research status and future directions toward its use in PSCs.

关键词： MXenes Perovskite solar cells Additives Interfacial layer Electrodes

Recent Progress on the Fabrication of Ultrafine Polyamide-6 Based Nanofibers Via Electrospinning: A Topical Review

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Nano-Micro Letters 2014年第2期6卷 89-107页

作者： R.Nirmala R.Navamathavan soo-jin park Hak Yong Kim Department of Organic Materials and Fiber Engineering Chonbuk National University Department of Chemistry Inha University School of Advanced Materials Engineering Chonbuk National University

Electrospinning is a highly versatile technique to prepare continuous fibers with diameters of the order of nanometers. The remarkable high aspect ratio and high porosity bring electrospun nanofibers highly attractive to various nanotechnological applications such as filtration membranes, protective clothing, drug delivery, tissue-engineering, biosensors, catalysis, fuel cells and so on. In this review, we collectively summarized the recent progress in developments of the electrospun ultrafine polyamide-6 based nanofibers preparation,characterization and their applications. Information of this polyamide-6 and composites together with their processing conditions for electrospinning of ultrafine nanofibers has been summarized in this review. The recent developments made during last few years on these materials are addressed in this review. We are anticipating that this review certainly drive the researchers for developing more intensive investigation for exploring in many technological areas.

关键词： Polymers Electrospinning Ultrafine nanofibers Experimental parameters

Optimistic performance of carbon-free hydrazine fuel cells based on controlled electrode structure and water management

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Journal of Energy Chemistry 2020年第12期29卷 175-181页

作者： Hongsun Hwang Sujik Hong Do-Hyeong Kim Moon-Sung Kang jin-soo park Sunghyun Uhm Jaeyoung Lee Electrochemical Reaction and Technology Laboratory(ERTL) School of Earth Sciences and Environmental EngineeringGwangju Institute of Science and Technology(GIST)Cwangju 61005Republic of Korea Ertl Center for Electrochemistry and Catalysis Gwangju Institute of Science and Technology(GIST)Gwangju 61005Republic of Korea Department of Green Chemical Engineering Sangmyung UniversityCheonanChungnam 31066Republic of Korea Plant Engineering Center Institute for Advanced EngineeringYongin 17180Republic of Korea

In this study, we first attempted to discover the optimal configuration of membrane-electrode assemblies(MEAs) used to achieve a high performance of direct hydrazine fuel cells(DHFCs). We have investigated the effect of water management and the electrode thickness on the performance of DHFCs, depending on the hydrophobicity of the gas diffusion layers in the cathode and the catalyst loading in the anode with the carbon-supported Ni, synthesized by a polyol process. With the optimal water management and electrode thickness, the MEA constructed using the as-prepared Ni/C anode catalyst containing the metallic and low oxidative state and ultra-low Pt loading cathode reduced the ohmic resistance and mass transfer limitation in the current-voltage curves observed for the alkaline DHFC, achieving an impressive power performance over 500 mW cm^(–2).

关键词： Fuel cell Hydrazine Alkaline media Membrane-electrode assembly

Interfacial Behaviors of Basalt Fiber‑Reinforced Polymeric Composites: A Short Review

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Advanced Fiber Materials 2022年第6期4卷 1414-1433页

作者： Seong‑Hwang Kim Jong‑Hoon Lee Jong‑Woo Kim Seul‑Yi Lee soo‑jin park Department of Chemistry Inha University100 InharoIncheon 22212South Korea

Basalt fibers(BFs)have emerged as a promising thermal insulation material for various applications,such as fireproof clothes/walls and protective equipment in military and civil *** have many desirable characteristics,such as low thermal conductivity,excellent flame resistance,exceptional mechanical strength,facile manipulability,environmental friendliness,and ***,the low intrinsic interfacial properties of BFs due to their chemical inertness and macro-scaled sizes have been a challenge for high performance of BFs-reinforced polymeric composites(BFRPs).Since the mechanical properties of BFRPs significantly depend on the interfacial interaction between the fibers and the matrix,it is critical to understand how incorporating BFs influences the properties of the *** this end,the aim of this review is to report on recent research progress with emphasis on the interfacial behavior in *** relationships between the fiber–matrix interfacial adhesion and the mechanical properties of the BFRPs are briefly described with systematic and up-to-date surface modification techniques summarized into two categories:surface modifications(“wet”and“dry”)and multi-scaled ***,several strategies for increasing the interfacial adhesion of BFs within the polymeric matrix to provide new ideas and insight for future research on the BFRPs are discussed.

关键词： Basalt fibers Polymeric matrix Surface modification Interface