检索结果-南通市图书馆

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

在线全文

学校读者我要写书评

暂无评论

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 technologies.However,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 unviable.Since 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 desirable.Alternative catalysts based on heteroatom-doped carbon nanomaterials,though showed good electrocatalytic activity yet their high cost and complex synthesis is not viable for scalable production.To 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 catalysts.The 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 durability.Thus,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 catalysts.In the present article,synthesis,N-doping,ORR/OER mechanism and electrocatalytic performance of biomassderived bifunctional catalysts has been discussed.The 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 process.The synthetic strategy could be further optimized to develop future biomass-based N self-doped porous carbons as metal-free high performance bifunctional oxygen catalysts for commercial energy applications

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

在线全文

学校读者我要写书评

暂无评论

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 catalysts.Although 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 sites.With 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 transfer.Herein,we prepare a Fe-N-C catalyst with magnetite particles and hierarchical pore structure by steam activation.The steam activation process significantly improves the power performance of the AHFC as indicated by the lower IR and activation voltage losses.Based 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

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

在线全文

学校读者我要写书评

暂无评论

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 systems.In the field of modern electronic packaging materials,there is a great need for graphitic material-loaded polymeric composites(GPCs)with excellent thermal conductivities.However,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 matrix.Understanding the interfaces between filler and matrix is of great importance in optimizing the performances of GPCs.Here,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 nanocomposites.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 nanocomposites.The experimental data presented herein demonstrate that the interfacial properties play a significant role in enhancing the thermal and mechanical performances of the nanocomposites.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

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

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

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 durability.However,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 equipment.In 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 composites.The 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,respectively.Excellent mechanical durability was demonstrated by stable electrical conductivity retention during 1000 cycles of bending test.An 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 coefficient.These results are attributed to the hierarchical architecture of the macroscale PF skeleton and nanoscale SWCNT/rGO networks,leading to superior EMI-shielding performance.We 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

Investigation of prodromal features in metabolic syndrome based on transcriptome analysis

在线全文

学校读者我要写书评

暂无评论

Genes & Diseases 2023年第3期10卷 708-711页

作者： Sang-Min park Musun park Hyo-Jeong Ban Su-jin Baek soo Yeon Kim Siwoo Lee Hee-Jeong jin Korean Medicine(KM)Data Division Korea Institute of Oriental MedicineDaejeon 34054Republic of Korea College of Pharmacy Chungnam National UniversityDaejeon 34134Republic of Korea

Metabolic syndrome(MetS)is a complex condition that significantly increases the risk of several diseases,including heart disease and diabetes.Patients with MetS show both pro-inflammatory and pro-thrombotic states;how... 详细信息

关键词： diseases Metabolic Patients

Fabrication of High-Density Out-of-Plane Microneedle Arrays with Various Heights and Diverse Cross-Sectional Shapes

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano-Micro Letters 2022年第2期14卷 60-78页

作者： Hyeonhee Roh Young Jun Yoon jin soo park Dong-Hyun Kang Seung Min Kwak Byung Chul Lee Maesoon Im Brain Science Institute Korea Institute of Science and Technology(KIST)Seoul 02792South Korea Division of Electrical Engineering College of EngineeringKorea UniversitySeoul 02841South Korea Micro/Nano Fabrication Center KISTSeoul 02792South Korea Division of Bio‑Medical Science&Technology KIST SchoolUniversity of Science&Technology(UST)Seoul 02792South Korea

Out-of-plane microneedle structures are widely used in various applications such as transcutaneous drug delivery and neural signal recording for brain machine interface.This work presents a novel but simple method to fabricate high-density silicon(Si)microneedle arrays with various heights and diverse cross-sectional shapes depending on photomask pattern designs.The proposed fabrication method is composed of a single photolithography and two subsequent deep reactive ion etching(DRIE)steps.First,a photoresist layer was patterned on a Si substrate to define areas to be etched,which will eventually determine the final location and shape of each individual microneedle.Then,the 1st DRIE step created deep trenches with a highly anisotropic etching of the Si substrate.Subsequently,the photoresist was removed for more isotropic etching;the 2nd DRIE isolated and sharpened microneedles from the predefined trench structures.Depending on diverse photomask designs,the 2nd DRIE formed arrays of microneedles that have various height distributions,as well as diverse cross-sectional shapes across the substrate.With these simple steps,high-aspect ratio microneedles were created in the high density of up to 625 microneedles mm^(-2)on a Si wafer.Insertion tests showed a small force as low as~172μN/microneedle is required for microneedle arrays to penetrate the dura mater of a mouse brain.To demonstrate a feasibility of drug delivery application,we also implemented silk microneedle arrays using molding processes.The fabrication method of the present study is expected to be broadly applicable to create microneedle structures for drug delivery,neuroprosthetic devices,and so on.

关键词： Microneedle Various heights Cross-sectional shapes Isotropic etch Deep reactive ion etching

A Review on Interface Engineering of MXenes for Perovskite Solar Cells

在线全文

学校读者我要写书评

暂无评论

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 harvester.However,the lack of stability and reliability in PSCs remained challenging for commercialization.Strategies,such as interfacial and structural engineering,have a more critical influence on enhanced performance.MXenes,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 properties.Owing 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 PSCs.Furthermore,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 PSCs.This 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 stability.Lastly,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

Adaptive Momentum-Backpropagation Algorithm for Flood Prediction and Management in the Internet of Things

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2023年第10期77卷 1053-1079页

作者： Jayaraj Thankappan Delphin Raj Kesari Mary Dong jin Yoon soo-Hyun park Department of Computer Science Muslim Arts CollegeManonmaniam Sundaranar UniversityThiruvitancodeTamil Nadu629174India Laboratory Special Communication&Convergence Service Research Center Kookmin UniversitySeoul02707Korea Development and Operation Support of Polar Research Equipment Korea Polar Research Institute(KOPRI)Incheon21990Korea Department of Financial Information Security Kookmin UniversitySeoul02707Korea

Flooding is a hazardous natural calamity that causes significant damage to lives and infrastructure in the real world.Therefore,timely and accurate decision-making is essential for mitigating flood-related damages.The traditional flood prediction techniques often encounter challenges in accuracy,timeliness,complexity in handling dynamic flood patterns and leading to substandard flood management strategies.To address these challenges,there is a need for advanced machine learning models that can effectively analyze Internet of Things(IoT)-generated flood data and provide timely and accurate flood predictions.This paper proposes a novel approach-the Adaptive Momentum and Backpropagation(AM-BP)algorithm-for flood prediction and management in IoT networks.The AM-BP model combines the advantages of an adaptive momentum technique with the backpropagation algorithm to enhance flood prediction accuracy and efficiency.Real-world flood data is used for validation,demonstrating the superior performance of the AM-BP algorithm compared to traditional methods.In addition,multilayer high-end computing architecture(MLCA)is used to handle weather data such as rainfall,river water level,soil moisture,etc.The AM-BP’s real-time abilities enable proactive flood management,facilitating timely responses and effective disaster mitigation.Furthermore,the AM-BP algorithm can analyze large and complex datasets,integrating environmental and climatic factors for more accurate flood prediction.The evaluation result shows that the AM-BP algorithm outperforms traditional approaches with an accuracy rate of 96%,96.4%F1-Measure,97%Precision,and 95.9%Recall.The proposed AM-BP model presents a promising solution for flood prediction and management in IoT networks,contributing to more resilient and efficient flood control strategies,and ensuring the safety and well-being of communities at risk of flooding.

关键词： Internet of Things flood prediction artificial neural network adaptive momentum backpropagation optimization disaster management

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

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

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 band.Moreover,a tunable frequency from a single transducer enables sonographers to achieve ultrasound images with a large detection area and high resolution.This facilitates the availability of more advanced techniques that simultaneously require low-and high-frequency ultrasounds,such as harmonic imaging and image-guided therapy.In 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 imaging.To switch the ultrasound frequency,the only requirement is to tune a DC bias to control the polarization state of the ferroelectric film.Flextensional vibration of the PMUT membrane strongly depends on the polarization state,producing low-and high-frequency ultrasounds from a single excitation frequency.This strategy for dual-frequency ultrasounds meets the requirement for either multielectrode configurations or heterodesigned elements,which are integrated into an array.Consequently,this technique significantly reduces the design complexity of transducer arrays and their associated driving circuits.

关键词： piezoelectric ferroelectric enable