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Fine-tuning electronic structure of N-doped graphitic carbon-supported Co- and Fe-incorporated Mo2C to achieve ultrahigh electrochemical water oxidation activity

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CARBON ENERGY 2024年第7期6卷 134-149页

作者： Sher Shah, Md. Selim Arif Jung, Hyeonjung Paidi, Vinod K. Lee, Kug-Seung Han, Jeong Woo Park, Jong Hyeok Yonsei Univ Dept Chem & Biomol Engn 50 Yonsei Ro Seoul South Korea Univ North Bengal Dept Chem Darjeeling W Bengal India Seoul Natl Univ Res Inst Adv Mat Dept Mat Sci & Engn Seoul 08826 South Korea pohang accelerator lab Beamline Div 80 Jigok Ro127 beon Gil Pohang 37673 South Korea European Synchrotron Radiat Facil F-38049 Grenoble France

Mo2C is an excellent electrocatalyst for hydrogen evolution reaction (HER). However, Mo2C is a poor electrocatalyst for oxygen evolution reaction (OER). Herein, two different elements, namely Co and Fe, are incorporated in Mo2C that, therefore, has a finely tuned electronic structure, which is not achievable by incorporation of any one of the metals. Consequently, the resulting electrocatalyst Co0.8Fe0.2-Mo2C-80 displayed excellent OER catalytic performance, which is evidenced by a low overpotential of 214.0 (and 246.5) mV to attain a current density of 10 (and 50) mA cm(-2), an ultralow Tafel slope of 38.4 mV dec(-1), and long-term stability in alkaline medium. Theoretical data demonstrates that Co0.8Fe0.2-Mo2C-80 requires the lowest overpotential (1.00 V) for OER and Co centers to be the active sites. The ultrahigh catalytic performance of the electrocatalyst is attributed to the excellent intrinsic catalytic activity due to high Brunauer-Emmett-Teller specific surface area, large electrochemically active surface area, small Tafel slope, and low charge-transfer resistance.

关键词： fine-tuning electronic structures heteronanostructures Mo2C multimetal (Co/Fe) oxygen evolution reaction OXYGEN EVOLUTION REACTION MOLYBDENUM CARBIDE NANOPARTICLES HYDROGEN EVOLUTION BIFUNCTIONAL ELECTROCATALYST EFFICIENT COBALT COMPLEX

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Giant chiro-optical responses in multipolar-resonances-based single-layer dielectric metasurfaces

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Photonics Research 2021年第9期9卷 1667-1674页

作者： HAFIZ SAAD KHALIQ INKI KIM AIMA ZAHID JOOHOON KIM TAEJUN LEE TREVON BADLOE YESEUL KIM MUHAMMAD ZUBAIR KASHIF RIAZ MUHAMMAD QASIM MEHMOOD JUNSUK RHO NanoTech lab Department of Electrical EngineeringInformation Technology University(ITU)of the PunjabLahore 54600Pakistan Department of Mechanical Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea Department of Chemical Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea POSCO-POSTECH-RIST Convergence Research Center for Flat Optics and Metaphotonics Pohang 37673Republic of Korea National Institute of Nanomaterials Technology(NINT) Pohang 37673Republic of Korea

Chiro-optical effects offer a wide range of potential applications in nanophotonics,such as advanced imaging and molecular sensing and *** single-layer metasurfaces composed of subwavelength meta-atoms have gained significant attention due to their exceptional characteristics in light–matter *** metasurface-based devices have manipulated electromagnetic waves,the compact on-chip realization of giant chiro-optical effects remains a challenge at optical *** this work,we experimentally and numerically demonstrate an all-dielectric metasurface to realize large chiro-optical effects in the visible ***,the proposed strategy of utilizing achiral nanofins instead of conventional chiral structures provides an extra degree of design *** mutual coupling between carefully engineered nanofins produces constructive and destructive interference,leading to the asymmetric transmission of 70%and average circular dichroism exceeding 60%.We investigate the underlying mechanism behind the chiro-optical effects using the theory of multipolar *** proposed design mechanism maximizes the chiro-optical response through a single-layer metasurface with potential applications in high-efficiency integrated ultrathin polarization rotators and shapers,chiral polarizers for optical displays,chiral beam splitters,and chiral sensors.

关键词： chiral dielectric polar

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Two birds with one stone: CEPR2 phosphorylates dual targets in ABA signaling

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Molecular Plant 2021年第4期14卷 550-551页

作者： Qianying Yang Youngsook Lee Department of Life Sciences POSTECHPohang 37673Republic of Korea

Abscisic add(ABA)is a major phytohormone that governs plant development and their responses to many stressors(Chen et al.,2020).After its biosynthesis in specific tissues and cells,ABA is transported throughout the plant and perceived by dedicated *** PYR/PYLVRCAR(pyrabactin resistance1/PYR1-like/regulatory components of A巳A receptor)proteins are such ABA receptors and are localized inside the *** to their location,and since ABA is often biosynthesized far from its target cells,ABA transporters are needed to move the phytohormone什om the cells that synthesize A巳A to the target cells.

关键词： receptor plant

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Protonic recognition and assembly for the creation of porous Br?nsted acid catalysts with enhanced catalytic efficiency

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Chinese Chemical Letters 2023年第8期34卷 184-187页

作者： Liping Huang Mingyun Liang Yajun Fang Jehan Kim Yuntian Yang Zhegang Huang PCFM LIFM Lab School of Chemistry Sun Yat-sen University Shenzhen Grubbs Institute Department of Chemistry Southern University of Science and Technology pohang accelerator laboratory 4. Guangdong Provincial Key laboratory of Optical Chemicals Xinhuayue Group

Due to the high local concentration of substrates in confined space, porous solid Br?nsted acids have been extensively explored for efficient acid-catalyzed reaction. However, the porous structures with strong Br?nsted acids lack long-term stability due to chemical hydrolysis. Moreover, the products inhibition effect in confined rigid cavities severely obstructs subsequent catalysis. Here, tubular Br?nsted acid catalyst with unique recognition of protons was presented by self-assembly of p H-responsive aromatic amphiphiles. The responsive assembly could mechanically transfer hydrogen ions from low-concentration acidic solution into tubular defined pores, thereby producing effective catalytic activity for Mannich reactions in mildly acidic solution. Notably, the tubular catalyst unfolded into flat sheets upon addition of triethylamine for efficient release of products, which could be recovered by subsequent acidification and the catalytic activity still remained. Therefore, the porous Br?nsted acid with reversible assembly provides a new strategy for mass synthesis through increasing conversion times.

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Optical spin-symmetry breaking for high-efficiency directional helicity-multiplexed metaholograms

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Microsystems & Nanoengineering 2021年第2期7卷 71-79页

作者： Muhammad Ashar Naveed Muhammad Afnan Ansari Inki Kim Trevon Badloe Joohoon Kim Dong Kyo Oh Kashif Riaz Tauseef Tauqeer Usman Younis Murtaza Saleem Muhammad Sabieh Anwar Muhammad Zubair Muhammad Qasim Mehmood Junsuk Rho NanoTech lab Department of Electrical EngineeringInformation Technology University(ITU)of the PunjabFerozepur RoadLahore54600Pakistan Department of Mechanical Engineering Pohang University of Science and Technology(POSTECH)Pohang37673Republic of Korea Department of Physics Lahore University of Management Sciences(LUMS)Lahore54792Pakistan Department of Chemical Engineering Pohang University of Science and Technology(POSTECH)Pohang37673Republic of Korea National Institute of Nanomaterials and Technology(NINT) Pohang37673Republic of Korea

Helicity-multiplexed metasurfaces based on symmetric spin–orbit interactions (SOIs) have practical limits because they cannot provide central-symmetric holographic imaging. Asymmetric SOIs can effectively address such limitations, with several exciting applications in various fields ranging from asymmetric data inscription in communications to dual side displays in smart mobile devices. Low-loss dielectric materials provide an excellent platform for realizing such exotic phenomena efficiently. In this paper, we demonstrate an asymmetric SOI-dependent transmission-type metasurface in the visible domain using hydrogenated amorphous silicon (a-Si:H) nanoresonators. The proposed design approach is equipped with an additional degree of freedom in designing bi-directional helicity-multiplexed metasurfaces by breaking the conventional limit imposed by the symmetric SOI in half employment of metasurfaces for one circular handedness. Two on-axis, distinct wavefronts are produced with high transmission efficiencies, demonstrating the concept of asymmetric wavefront generation in two antiparallel directions. Additionally, the CMOS compatibility of a-Si:H makes it a cost-effective alternative to gallium nitride (GaN) and titanium dioxide (TiO2) for visible light. The cost-effective fabrication and simplicity of the proposed design technique provide an excellent candidate for high-efficiency, multifunctional, and chip-integrated demonstration of various phenomena.

关键词： directional breaking visible

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SVM-based Biological Named Entity Recognition using Minimum Edit-Distance Feature Boosted by Virtual Examples

SVM-based Biological Named Entity Recognition using Minimum ...

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第一届自然语言处理联合学术会议

作者： Eunji Yi Gary Geunbae Lee Soo-Jun Park Department of CSE POSTECH pohang Department of CSE POSTECH pohang Bioinformatics Research Team Computer and Software Research lab.ETRI Taejon

＜正＞In this paper, we propose two indepentent solutions to resolve the problems of many different spelling variants and of lack of annotated corpus for training, which are two main difficulties in SVM（Support-Vector Machine） and other machine-learning based biological named entity recognition. To resolve the problem of spelling variants, we propose a use of edit-distance as a feature for SVM. We also propose a use of virtual examples to automatically expand the annotated corpus to resolve the lack-of-corpus problem. Using virtual examples, the annotated corpus can be expanded in a fast, efficient and easy way. The experimental results show that the introduction of edit-distance produces some improvements in named entity recognition performance. And the model, which is trained with the corpus expanded by virtual examples, outperforms the model trained with the original corpus. According to the proposed methods, we finally achieved the high performance of 71.46 % in F-measure （64.03 % in precision, 80.84 % in recall） in the experiment of five category named entity recognition on GE-NIA corpus （ver. 3.0）.

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Epoxy resin nanocomposites reinforced with ionized liquid stabilized carbon nanotubes

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International Journal of Smart and Nano Materials 2011年第3期2卷 176-193页

作者： Zhe Wang Xiongtao Yang Qiang Wang H.Thomas Hahn Sang-gi Lee Kun-Hong Lee Zhanhu Guo Mechanical&Aerospace Engineering Department University of California Los AngelesLos AngelesCA 90095USA Integrated Composites lab Dan F.Smith Department of Chemical EngineeringLamar UniversityBeaumontTX 77710USA Institute of Chemical and Engineering Sciences(ICES) A-STARApplied Catalysis1Pesek RoadJurong Island627833 Singapore Department of Chemistry and Nano Science Ewha Womans UniversitySeoul 120-750Korea Department of Chemical Engineering Pohang University of Science and TechnologyPohang 790-784Korea

Epoxy resin nanocomposites reinforced with three different ionic liquid functionalized carbon nanotubes(f-CNTs)were fabricated by an in situ polymerization *** influence of the anions on the curing process was studied through differential scanning calorimetry(DSC)and normalized Fourier transform infrared(FTIR)*** composition of the nanocomposites was analyzed by X-ray photoelectron *** different mechanisms are proposed to explain the curing process of the neat epoxy and its *** electric conductivity and mechanical properties of the nanocomposites are also *** tensile strength was increased dramatically due to the insertion of *** electron microsopy fracture surface analysis indicates a strong interfacial bonding between the carbon nanotubes and the polymer matrix.

关键词： epoxy resin nanocomposite carbon nanotube ionic liquid functionalization

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Protonic recognition and assembly for the creation of porous Bronsted acid catalysts with enhanced catalytic efficiency

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中国化学快报:英文版 2023年第8期34卷 158-161页

作者： Liping Huang Mingyun Liang Yajun Fang Jehan Kim Yuntian Yang Zhegang Huang PCFM LIFM LabSchool of ChemistrySun Yat-sen UniversityGuangzhou 510275China Guangdong Provincial Key laboratory of Optical Chemicals Xinhuayue GroupMaoming 525000China Shenzhen Grubbs Institute Department of ChemistrySouthern University of Science and TechnologyShenzhen 518055China pohang accelerator laboratory PostechPohangGyeongbukKorea

Due to the high local concentration of substrates in confined space, porous solid Bronsted acids have been extensively explored for efficient acid-catalyzed reaction. However, the porous structures with strong Bronsted acids lack long-term stability due to chemical hydrolysis. Moreover, the products inhibition effect in confined rigid cavities severely obstructs subsequent catalysis. Here, tubular Bronsted acid catalyst with unique recognition of protons was presented by self-assembly of p H-responsive aromatic amphiphiles. The responsive assembly could mechanically transfer hydrogen ions from low-concentration acidic solution into tubular defined pores, thereby producing effective catalytic activity for Mannich reactions in mildly acidic solution. Notably, the tubular catalyst unfolded into flat sheets upon addition of triethylamine for efficient release of products, which could be recovered by subsequent acidification and the catalytic activity still remained. Therefore, the porous Bronsted acid with reversible assembly provides a new strategy for mass synthesis through increasing conversion times.

关键词： Tubular Brosted acid Protonic recognition Dynamic assembly Heterogeneous catalysis Large-scale synthesis

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Development of a hybrid scaffold and a bioreactor for cartilage regeneration

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Chinese Science Bulletin 2009年第19期54卷 3608-3612页

作者： LEE Seung-Jae LEE In Hwan PARK Jeong Hun GWAK So-Jung RHIE Jong-Won CHO Dong-Woo KO Tae Jo KIM Dong Sung BK21 Mechatronics Group at Chungnam National University School of Mechanical Engineering Chungbuk National University DDS Research lab. CKD Research Institute CKD Pharmaceutical Corp. Department of Plastic Surgery College of Medicine The Catholic University of Korea Department of Mechanical Engineering Pohang University of Science and Technology School of Mechanical Engineering Yeungnam University School of Mechanical Engineering Chung-Ang University

We developed a hybrid scaffold and a bioreactor for cartilage regeneration. The hybrid scaffold was developed as combination of two components: a biodegradable framework and hydrogel-containing chondrocytes. We performed the MTT cell proliferation assay to compare the proliferation and viability of chondrocytes on three types of scaffolds: an alginate gel, the hybrid scaffold, and an alginate sponge. Cells were encapsulated in 2% agarose gel. The bioreactor consisted of a circulation system and a compression system. We performed dynamic cell culture on these agarose gels in the bioreactor for 3 days.

关键词： MTT 生物分解凝解胶研究

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lon migration suppression mechanism via 4-sulfobenzoic acid monopotassium salt for 22.7%stable perovskite solar cells

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Science China Materials 2022年第12期65卷 3368-3381页

作者： Le Bai Fang Yao Rui Wang Baibai Liu Dongmei He Qian Zhou Wenqi Wang Cunyun Xu Xiaobo Hu Shaoqiang Chen Qunliang Song Tingwei Zhou Donghwa Lee Pengjun Zhao Cong Chen Hua Yang Qianqian Lin Zhigang Zang Jiangzhao Chen Key laboratory of Optoelectronic Technology&Systems(Ministry of Education) College of Optoelectronic EngineeringChongqing UniversityChongqing 400044China Key lab of Artificial Micro-and Nano-Structures of Ministry of Education of China School of Physics and TechnologyWuhan UniversityWuhan 430072China Department of Electronic Engineering East China Normal UniversityShanghai 200241China Institute for Clean Energy and Advanced Materials School of Materials and EnergySouthwest UniversityChongqing 400715China School of Physical Science and Technology Southwest UniversityChongqing 400715China Department of Materials Science and Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Korea Xinjiang Technical Institute of Physics and Chemistry Chinese Academy of SciencesUrumqi 830011China School of Material Science and Engineering State Key Laboratory of Reliability and Intelligence of Electrical EquipmentHebei University of TechnologyTianjin 300130China Spallation Neutron Source Science Center Institute of High Energy PhysicsUniversity of Chinese Academy of Sciences(CAS)Dongguan 523803China

The deep-level traps at grain boundaries(GBs)and halide ion migration are quite challenging for further enhancement of the stability and efficiency of perovskite solar cells(PSCs)as well as for the elimination of notorious ***,we report a large-sized strongly coordinated organic anion GB anchoring strategy for suppressing ion migration and passivating defects in planar *** practical implementation of this strategy involves the incorporation of potassium salts containing a large-sized organic counter anion(4-sulfobenzoic acid monopotassium salt,SAMS)into the perovskite *** has been found that anions within SAMS can be firmly anchored at GBs due to the strong coordination interaction between C=O and/or S=O at both ends of bulky anion and undercoordinated Pb^(2+)and/or halide vacancies,along with the hydrogen bond between–OH and *** can not only passivate shallowlevel defects but also cause more effective passivation of the deep-level *** GB manipulation strategy results in a reduced defect density,an increased carrier lifetime as well as suppressed ion migration,which in turn contributed to enhanced efficiency and stability of PSCs together with a thorough elimination of *** a result,the SAMSmodified device with an outstanding fill factor of 0.84 delivers a significant improvement in efficiency(22.7%)in comparison with the control device(20.3%).The unencapsulated modified device demonstrates only little degradation after 1320 h at 60℃.

关键词： perovskite solar cells ion migration suppression defect passivation large-sized organic anions potassium cations

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