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Biomimetic Fe_(7)S_(8)/Carbon electrocatalyst from[FeFe]-Hydrogenase for improving pH-Universal electrocatalytic hydrogen production Special Collection:Aggregation-Induced Processes and Functions

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Aggregate 2024年第1期5卷 451-459页

作者： dohun kim Subramani Surendran Sejin Im Jaehyoung Lim Kyoungsuk Jin Ki Tae Nam Uk Sim Department of Energy Science&Engineering Daegu Gyeongbuk Institute of Science&Technology(DGIST)DaeguRepublic of Korea Hydrogen Energy Technology Laboratory Korea Institute of Energy Technology(KENTECH)NajuRepublic of Korea Department of Chemistry Korea UniversitySeoulRepublic of Korea Department of Materials Science and Engineering Seoul National UniversitySeoulRepublic of Korea

Efficient and cost-effective electrocatalysts that can operate across a wide range of pH conditions are essential for green hydrogen *** by biological systems,Fe_(7)S_(8)nanoparticles incorporated on polydopamine matrix electrocatalyst were synthesized by co-precipitation and annealing *** resulting Fe_(7)S_(8)/C electrocatalyst possesses a three-dimensional structure and exhibits enhanced electrocatalytic performance for hydrogen production across various pH ***,the Fe_(7)S_(8)/C electrocatalyst demonstrates exceptional activity,achieving low overpotentials of 90.6,45.9,and 107.4 mV in acidic,neutral,and alkaline environments,*** impedance spectroscopy reveals that Fe_(7)S_(8)/C exhibits the lowest charge transfer resistance under neutral conditions,indicating an improved proton-coupled electron transfer ***-wave electron paramagnetic resonance results confirm a change in the valence state of Fe from 3+to 1+during the hydrogen evolution reaction(HER).These findings closely resemble the behavior of natural[FeFe]-hydrogenase,known for its superior hydrogen production in neutral *** remarkable performance of our Fe_(7)S_(8)/C electrocatalyst opens up new possibilities for utilizing bioinspired materials as catalysts for the HER.

关键词： biomimetic electrocatalyst hydrogen production renewable energy

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Disintegration Process and Performance of a Coaxial Porous Injector

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Journal of Thermal Science 2016年第5期25卷 394-401页

作者： Keonwoong Lee dohun kim Jaye Koo Graduate School Korea Aerospace University School of Aerospace and Mechanical Engineering Korea Aerospace University

In order to understand the breakup performance of coaxial porous injectors,the sprays of coaxial porous injectors with two different porous material cylinder lengths were compared with those of conventional shear coaxial *** allow comparison,the wall injection lengths were designed to be equivalent to the value of the recess *** flow sprays were visualized using back-lit photography methods and analyzed quantitatively with a laser diffraction apparatus,in order to study the effects of the momentum flux ratio and Weber number on the breakup for each type of *** case of the shear coaxial injector,the large liquid core was observed in low air mass flow rate ***,the destabilization of the liquid jet from the coaxial porous injector is almost complete within the inner region,near the injector face ***,better breakup performance in low gas flow rate condition was obtained when the porous cylinder length decreased,while the shear coaxial injectors showed better breakup efficiency when the recess length *** conclusion,the different breakup process caused by the radial momentum in the inner region of the porous injector disintegrated the liquid core.

关键词：多孔喷嘴同轴性能破碎效率崩解喷油器喷射器多孔材料

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Breakup Structure of Two-phase Jets with Various Momentum Flux from a Porous Injector

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Journal of Thermal Science 2014年第1期23卷 60-67页

作者： Inchul Lee dohun kim Jaye Koo Graduate Student Korea Aerospace University School of Aerospace and Mechanical Engineering Korea Aerospace University

Spray structure and atomization characteristics were investigated through a comparison of a porous and a shear coaxial injector. The porous injector shows better atomization performance than the shear coaxial injector. To increase atomization performance and mixing efficiency of two-phase jets, a coaxial porous injector which can be applicable to liquid rocket combustors was designed and tested. The characteristics of atomization and spray from a porous and a shear coaxial injector were characterized by the momentum flux ratio. The breakup mechanism of the porous injector is governed by Taylor-Culick flow and axial shear forces. Momentum of injected gas flow through a porous material which is composed of sintered metal is radically transferred to the center of the liquid column, and then liquid column is effectively broken up. Although the shapes of spray from porous and shear coaxial jets were similar for various momentum ratio, spray structures such as spray angle and droplet sizes were different. As increasing the momentum flux ratio, SMD from the porous injector showed smaller value than the shear coaxial

关键词：多孔材料动量通量两相射流喷油器结构通量分裂同轴射流雾化特性

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Effects of Supercritical Environment on Hydrocarbon-fuel Injection

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Journal of Thermal Science 2017年第2期26卷 183-191页

作者： Bongchul Shin dohun kim Min Son Jaye Koo Graduate School Korea Aerospace UniversityGoyangRepublic of Korea School of Aerospace and Mechanical Engineering Korea Aerospace UniversityGoyangRepublic of Korea

In this study, the effects of environment conditions on decane were investigated. Decane was injected in subcritical and supercritical ambient conditions. The visualization chamber was pressurized to 1.68 MPa by using nitrogen gas at a temperature of 653 K for subcritical ambient conditions. For supercritical ambient conditions, the visualization chamber was pressurized to 2.52 MPa by using helium at a temperature of 653 K. The decane injection in the pressurized chamber was visualized via a shadowgraph technique and gradient images were obtained by a post processing method. A large variation in density gradient was observed at jet interface in the case of subcritical injection in subcritical ambient conditions. Conversely, for supercritical injection in supercritical ambient conditions, a small density gradient was observed at the jet interface. In a manner similar to that observed in other cases, supercritical injection in subcritical ambient conditions differed from supercritical ambient conditions such as sphere shape liquid. Additionally, there were changes in the interface, and the supercritical injection core width was thicker than that in the subcritical injection. Furthermore, in cases with the same injection conditions, the change in the supercritical ambient normalized core width was smaller than the change in the subcritical ambient normalized core width owing to high specific heat at the supercritical injection and small phase change at the interface. Therefore, the interface was affected by the changing ambient condition. Given that the effect of changing the thermodynamic properties of propellants could be essential for a variable thrust rocket engine, the effects of the ambient conditions were investigated experimentally.

关键词： Decane 喷气 Subcritical Supercritical 可视化

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A sulfur self-doped multifunctional biochar catalyst for overall water splitting and a supercapacitor from Camellia japonica flowers

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Carbon Energy 2022年第4期4卷 491-505页

作者： Chengkai Xia Subramani Surendran Seulgi Ji dohun kim Yujin Chae Jaekyum kim Minyeong Je Mi-Kyung Han Woo-Seok Choe Chang Hyuck Choi Heechae Choi Jung Kyu kim Uk Sim School of Chemistry Engineering Sungkyunkwan UniversitySuwonRepublic of Korea Hydrogen Energy Technology Laboratory Korea Institute of Energy Technology(KENTECH)NajuRepublic of Korea Department of Materials Science&Engineering Chonnam National UniversityGwangjuRepublic of Korea Theoretical Materials&Chemistry Group University of CologneCologneGermany Research Institute NEEL SciencesInc.NajuSouth Korea Department of Chemistry Pohang University of Science and Technology(POSTECH)Gyeongsangbuk-doRepublic of Korea

A versatile use of a sulfur self-doped biochar derived from Camellia japonica(camellia)flowers is demonstrated as a multifunctional catalyst for overall water splitting and a *** native sulfur content in the camellia flower facilitates in situ self-doping of sulfur,which highly activates the camellia-driven biochar(SA-Came)as a multifunctional catalyst with the enhanced electron-transfer ability and long-term *** water splitting,an SA-Came-based electrode is highly stable and shows reaction activities in both hydrogen and oxygen evolution reactions,with overpotentials of 154 and 362 mV at 10 mA cm^(−2),*** supercapacitors,SA-Came achieves a specific capacitance of 125.42 F g^(−1)at 2 A g^(−1)and high cyclic stability in a three-electrode system in a 1 M KOH *** demonstrated a high energy density of 34.54 Wh kg^(−1)at a power density of 1600 W kg^(−1)as a symmetric hybrid supercapacitor device with a wide working potential range of 0-1.6 V.

关键词： activated carbon biomass supercapacitor sustainable chemistry water splitting

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Contained local compression on peri-ascending aortic area for postoperative bleeding control:a case report

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The Journal of Biomedical Research 2021年第1期35卷 72-74页

作者： Su Young Yoon Si-Wook kim dohun kim Jong-Myeon Hong Department of Thoracic and Cardiovascular Surgery 2Trauma CenterChungbuk National University HospitalCollege of MedicineChungbuk National UniversitySeowon-GuCheongju 28644Republic of Korea

After type A acute aortic dissection(AAD)repair or modified Bentall procedure,uncontrollable bleeding from the anastomotic sites of the fragile dissected tissues or aortic root area is a critical situation to a cardiac *** postoperative care,lots of blood transfusion with strict monitoring on the patient all night and subsequent reoperation for the bleeding control is usually *** managed to make contained local compression of upper half of the heart,from upper part of the right ventricle to just above the innominate vein,using bovine pericardium with closing both sides of transverse sinus in two cases of uncontrolled postoperative bleeding(bleeding from distal anastomotic site in type-A AAD and valve sitting site in modified Bentall procedure).Even though reoperations for the removal of packed gauges were done in both cases 2 days later,postoperative courses at intensive care unit were very smooth with little need for *** kind of contained local compression trial could be a useful strategy for dealing with the malignant uncontrollable bleeding from the fragile aortic tissue or root area after acute dissection or aortic root repair.

关键词： uncontrollable bleeding contained local compression aortic dissection aortic root repair

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Enhancing the efficiency and scalability of perovskite solar cells through pseudo-halide salt addition

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Journal of Materials Science & Technology 2023年第34期165卷 161-169页

作者： dohun Baek Geon Yeong Park Jeongbeom Cha Hyemi Na Dong Seok Ham Min kim School of Chemical Engineering Future Energy Research CenterJeonbuk National UniversityJeonju 54896Republic of Korea Graduate School of Integrated Energy-AI Jeonbuk National UniversityJeonju 54896Republic of Korea Chemical Materials Solutions Center Korea Research Institute of Chemical Technology(KRICT)Daejeon 34114Republic of Korea

Organic-inorganic halide perovskites have significant potential for application in next-generation solar ***,their applications are limited by challenges associated with large-area processability and long-term stability owing to the presence of pinholes and defect ***,we incorporated cesium formate in a perovskite active layer using a sequential perovskite fabrication process to eliminate the defect sites of perovskites and improve the film processability via roll-to-roll(R2R)*** addition of cesium formate salt to the PbI2 layer influences the perovskite crystal formation behavior as well as increases the perovskite crystallinity and decreases the defect ***,cesium formate addition eliminated small PbI2 grains and smoothed the perovskite surface,resulting in a large crystal grain *** formate ions interact with the PbI2 component and passivate halide vacancy defects,reducing nonradiative recombination and improving charge ***,the treated perovskite films were highly stable in air,exhibiting improved efficiency retention over time and achieving a power conversion efficiency(PCE)of>22%compared to the ***,the additive-treated perovskite film was processed using the R2R method,achieving a high PCE of>14%with minimal hysteresis.

关键词： Perovskite Solar Cells Pseudo-halide ion Stability Roll-to-roll process

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Path to the fabrication of efficient, stable and commercially viable large-area organic solar cells

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Materials Futures 2023年第3期2卷 38-52页

作者： Shafket Rasool Jiwoo Yeop Hye Won Cho Woojin Lee Jae Won kim dohun Yuk JinYoung kim School of Energy and Chemical Engineering Ulsan National Institute of Science and TechnologyUlsan 44919Republic of Korea Graduate School of Carbon Neutrality Ulsan National Institute of Science and TechnologyUlsan44919Republic of Korea

Organic solar cells(OSCs)have reached an outstanding certified power conversion efficiency(PCE)of over 19%in single junction and 20%in tandem architecture *** high PCEs have emerged with outstanding Y-shaped Y6 non-fullerene acceptors(NFAs),together with PM6 electron donor *** are on the rise for small-area ***,large-area OSC sub-modules are still unable to achieve such high PCEs,and the highest certified PCE reported so far is∼12%having an area of 58 *** fabricate efficient large-area OSCs,new custom-designed NFAs for large-area systems are imminent along with improvements in the sub-module fabrication ***,the search for stable yet efficient OSCs is still in *** this review,progress in small-area OSCs is presented with reference to the advancement in the chemical structure of NFAs and donor ***,the life-cycle assessment of OSCs is presented and the energy payback time of the efficient and stable OSCs is discussed and lastly,an outlook for the OSCs is given.

关键词： organic solar cells non-fullerene acceptors OSC morphology interfacial modification light-soaking stability solar energy large-area OSCs

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