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Chemical modification of ordered/disordered carbon nanostructures for metal hosts and electrocatalysts of lithium-air batteries

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InfoMat 2022年第1期4卷 105-129页

作者： Jeongyeon Lee Tae Hyung Lee ho won jang ho Seok Park School of Chemical Engineering Convergence Research Center for Energy and Environmental SciencesDepartment of Health Sciences and TechnologySamsung Advanced Institute for Health Sciences and Technology(SAIHST)Sungkyunkwan University(SKKU)SuwonRepublic of Korea Institute of Textiles Clothing The Hong Kong Polytechnic UniversityHung HomHong Kong SARChina Department of Materials Science and Engineering Research Institute of Advanced MaterialsSeoul National UniversitySeoulRepublic of Korea

Although lithium-air batteries(LABs)are considered the promising alternative of existing lithium–ion batteries owing to their high energy density of 11680 W h kg^(-1),their practical applications are limited by the technical issues,such as unstable solid electrolyte interface and dendrite formation from metal anode and insufficient bifunctional activities and durability from cathode *** order to resolve these bottlenecks,carbon nanostructures have been investigated owing to their high surface area,excellent electrical conductivity,electrochemical stability,and various modification ***,we comprehensively review a recent progress on the design of carbon nanostructures for their applications into metal hosts,protection layers,and bifunctional electrocatalysts of *** correlation between the crystalline,electronic,porous,and chemical structures and the electrochemical properties of carbon nanomaterials are discussed depending on their classification and *** chemical modifications,such as morphological control,hierarchical architecturing,heteroatom incorporation,and the formation of composites,for the improved electrochemical performances of anode and cathode will be also ***,we deal with the perspectives for the ongoing obstruction and future guidance.

关键词： bifunctional catalysts carbon nanostructures lithium-air batteries metal anodes surface modification

Memristive Devices Based on Two-Dimensional Transition Metal Chalcogenides for Neuromorphic Computing

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Nano-Micro Letters 2022年第4期14卷 29-58页

作者： Ki Chang Kwon Ji Hyun Baek Kootak hong Soo Young Kim ho won jang Department of Materials Science and Engineering Research Institute of Advanced MaterialsSeoul National UniversitySeoul 08826Republic of Korea Interdisciplinary Materials Measurement Institute Korea Research Institute of Standards and Science(KRISS)Daejeon 34133Republic of Korea Department of Materials Science and Engineering Institute of Green Manufacturing TechnologyKorea UniversitySeoul 02841Republic of Korea Advanced Institute of Convergence Technology Seoul National UniversitySuwon 16229Korea

Two-dimensional(2D)transition metal chalcogenides(TMC)and their heterostructures are appealing as building blocks in a wide range of electronic and optoelectronic devices,particularly futuristic memristive and synaptic devices for brain-inspired neuromorphic computing *** distinct properties such as high durability,electrical and optical tunability,clean surface,flexibility,and LEGO-staking capability enable simple fabrication with high integration density,energy-efficient operation,and high *** review provides a thorough examination of high-performance memristors based on 2D TMCs for neuromorphic computing applications,including the promise of 2D TMC materials and heterostructures,as well as the state-of-the-art demonstration of memristive *** challenges and future prospects for the development of these emerging materials and devices are also *** purpose of this review is to provide an outlook on the fabrication and characterization of neuromorphic memristors based on 2D TMCs.

关键词： Two-dimensional materials Memristors Neuromorphic computing Artificial synapses Transition metal chalcogenides

Enhancing BiVO_(4)photoanode performance by insertion of an epitaxial BiFeO_(3)ferroelectric layer

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Journal of Energy Chemistry 2024年第2期89卷 71-78,I0003页

作者： Haejin jang Yejoon Kim hojoong Choi Jiwoong Yang Yoonsung Jung Sungkyun Choi Donghyeon Lee ho won jang Sanghan Lee School of Materials Science and Engineering Gwangju Institute of Science and TechnologyGwangju 61005Republic of Korea Department of Materials Science and Engineering Seoul National UniversitySeoul 08826Republic of Korea

BiVO_(4)(BVO)is a promising material as the photoanode for use in photoelectrochemical ***,the high charge recombination and slow charge transfer of the BVO have been obstacles to achieving satisfactory photoelectrochemical *** address this,various modifications have been attempted,including the use of ferroelectric *** materials can form a permanent polarization within the layer,enhancing the separation and transport of photo-excited electron-hole *** this study,we propose a novel approach by depositing an epitaxial BiFeO_(3)(BFO)thin film underneath the BVO thin film(BVO/BFO)to harness the ferroelectric property of *** self-polarization of the inserted BFO thin film simultaneously functions as a buffer layer to enhance charge transport and a hole-blocking layer to reduce charge *** a result,the BVO/BFO photoanodes showed more than 3.5 times higher photocurrent density(0.65 mA cm^(-2))at 1.23 V_(RHE)under the illumination compared to the bare BVO photoanodes(0.18 m A cm^(-2)),which is consistent with the increase of the applied bias photon-to-current conversion efficiencies(ABPE)and the result of electrochemical impedance spectroscopy(EIS)*** results can be attributed to the self-polarization exhibited by the inserted BFO thin film,which promoted the charge separation and transfer efficiency of the BVO photoanodes.

关键词： Photoelectrochemical Photoanode BiVO_(4) Ferroelectric materials BiFeO_(3)

Reduced graphene oxide-based materials for electrochemical energy conversion reactions

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Carbon Energy 2019年第1期1卷 85-108页

作者： Seokhoon Choi Changyeon Kim Jun Min Suh ho won jang Department of Materials Science and Engineering Seoul National UniversitySeoulRepublic of Korea

There have been ever-growing demands to develop advanced electrocatalysts for renewable energy conversion over the past *** a promising platform for advanced electrocatalysts,reduced graphene oxide(rGO)has attracted substantial research interests in a variety of electrochemical energy conversion *** versatile utility is mainly attributed to unique physical and chemical properties,such as high specific surface area,tunable electronic structure,and the feasibility of structural modification and ***,a comprehensive discussion is provided upon recent advances in the material preparation,characterization,and the catalytic activity of rGO-based electrocatalysts for various electrochemical energy conversion reactions(water splitting,CO2 reduction reaction,N2 reduction reaction,and O2 reduction reaction).Major advantages of rGO and the related challenges for enhancing their catalytic performance are addressed.

关键词： CO2 reduction reaction electrocatalysis N2 reduction reaction O2 reduction reaction reduced graphene oxide water splitting

Porously Reduced 2-Dimensional Bi_(2)O_(2)CO_(3) Petals for Strain-Mediated Electrochemical CO_(2) Reduction to HCOOH

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Energy & Environmental Materials 2024年第1期7卷 215-221页

作者： won Seok Cho Dae Myung hong Wan Jae Dong Tae Hyung Lee Chul Jong Yoo Donghwa Lee ho won jang Jong-Lam Lee Department of Materials Science and Engineering Pohang University of Science and Technology(POSTECH)Pohang Gyungbuk 37673Korea Department of Materials Science and Engineering Research Institute of Advanced Materials Seoul National UniversitySeoul 08826Korea

Here we introduce bismuth-based catalysts for the efficient electrochemical reduction of CO_(2)to formic acid(HCOOH),which are composed of petal-shaped Bi_(2)O_(2)CO_(3)(BOC)that spontaneously formed from Bi thin film in aqueous carbonate solution at room *** the electrochemical reduction process,the BOC petals transform to reduced BOC(R-BOC)consisting of individual BOC and Bi *** mismatch between both domains induces biaxial strain at the *** functional theory calculations suggest that the tensile strain on the Bi domain stabilizes the*OCho intermediate,reducing the thermodynamic barrier toward CO_(2)conversion to *** with the thermodynamic benefit and the unique nanoporous petal-shaped morphology,R-BOC petals have a superior Faradaic efficiency of 95.9%at-0.8 V_(RHE)for the electrochemical conversion of CO_(2)to *** work demonstrates that the spontaneously formed binary phases with desirable lattice strain can increase the activity of bismuth catalysts to the CO_(2)reduction reaction;such a strategy can be applicable in design of various electrocatalysts.

关键词： bismuth carbon dioxide reduction formic acid heterointerfaces strain

A review of understanding electrocatalytic reactions in energy conversion and energy storage systems via scanning electrochemical microscopy

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Journal of Energy Chemistry 2024年第4期91卷 155-177页

作者： Jihye Park Jong Hwan Lim Jin-Hyuk Kang Jiheon Lim ho won jang hosun Shin Sun Hwa Park Interdisciplinary Materials Measurement Institute Korea Research Institute of Standards and ScienceDaejeon 34113Republic of Korea Department of Material Science and Engineering Seoul National UniversitySeoul 08826Republic of Korea Department of Applied Measurement Science University of Science and TechnologyDaejeon 34113Republic of Korea

To address climate change and promote environmental sustainability,electrochemical energy conversion and storage systems emerge as promising alternative to fossil fuels,catering to the escalating demand for *** optimal energy efficiency and cost competitiveness in these systems requires the strategic design of electrocatalysts,coupled with a thorough comprehension of the underlying mechanisms and degradation behavior occurring during the electrocatalysis *** electrochemical microscopy(SECM),an analytical technique for studying surface electrochemically,stands out as a powerful tool offering electrochemical *** possesses remarkable spatiotemporal resolution,enabling the visualization of the localized electrochemical activity and surface *** review compiles crucial research findings and recent breakthroughs in electrocatalytic processes utilizing the SECM methodology,specifically focusing on applications in electrolysis,fuel cells,and metal–oxygen batteries within the realm of energy conversion and storage *** with an overview of each energy system,the review introduces the fundamental principles of SECM,and aiming to provide new perspectives and broadening the scope of applied research by describing the major research categories within SECM.

关键词： Scanning electrochemical microscopy Electrocatalyst Electrocatalysis Water splitting Fuel cell Metal-oxygen battery

Towards high-performance and robust anion exchange membranes(AEMs)for water electrolysis:Super-acid-catalyzed synthesis of AEMs

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Journal of Energy Chemistry 2024年第6期93卷 478-510,I0012页

作者： Geun Woong Ryoo Sun Hwa Park Ki Chang Kwon Jong Hun Kang ho won jang Min Sang Kwon Department of Materials Science and Engineering Research Institute of Advanced Materials(RIAM)Seoul National UniversitySeoul 08826Republic of Korea Interdisciplinary Materials Measurement Institute Korea Research Institute of Standards and Science(KRISS)Daejeon 34113Republic of Korea Department of Chemical and Biological Engineering and Institute of Chemical ProcessSeoul National UniversitySeoul 08826Republic of Korea Department of Applied Measurement Science University of Science and TechnologyDaejeon 34113Republic of Korea

The increasing demand for hydrogen energy to address environmental issues and achieve carbon neutrality has elevated interest in green hydrogen production,which does not rely on fossil *** various hydrogen production technologies,anion exchange membrane water electrolyzer(AEMWE)has emerged as a next-generation technology known for its high hydrogen production efficiency and its ability to use non-metal ***,this technology faces significant challenges,particularly in terms of the membrane durability and low ionic *** address these challenges,research efforts have focused on developing membranes with a new backbone structure and anion exchange groups to enhance durability and ionic ***,the super-acid-catalyzed condensation(SACC)synthesis method stands out due to its user convenience,the ability to create high molecular weight(MW)polymers,and the use of oxygen-tolerant organic *** the synthesis of anion exchange membranes(AEMs)using the SACC method began in 2015,and despite growing interest in this synthesis approach,there remains a scarcity of review papers focusing on AEMs synthesized using the SACC *** review covers the basics of SACC synthesis,presents various polymers synthesized using this method,and summarizes the development of these polymers,particularly their building blocks including aryl,ketone,and anion exchange *** systematically describe the effects of changes in the molecular structure of each polymer component,conducted by various research groups,on the mechanical properties,conductivity,and operational stability of the *** review will provide insights into the development of AEMs with superior performance and operational stability suitable for water electrolysis applications.

关键词： Green hydrogen production Water electrolysis Anion exchange membrane water electrolyzer(AEMWE) Anion exchange membranes(AEMs) Super-acid-catalyzed condensation(SACC)

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

Crystallographically vacancy‐induced MOF nanosheet as rational single‐atom support for accelerating CO_(2) electroreduction to CO

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Carbon Energy 2024年第8期6卷 49-62页

作者： Jin Hyuk Cho Joonhee Ma Chaehyeon Lee Jin Wook Lim Youngho Kim ho Yeon jang Jaehyun Kim Myung‐gi Seo Youngheon Choi Youn Jeong jang Sang Hyun Ahn ho won jang Seoin Back Jong‐Lam Lee Soo Young Kim Department of Materials Science and Engineering Korea UniversitySeoulRepublic of Korea Department of Chemical and Biomolecular Engineering Sogang UniversitySeoulRepublic of Korea Department of Materials Science and Engineering Pohang University of Science and Technology(POSTECH)PohangRepublic of Korea Department of Materials Science and Engineering Research Institute of Advanced MaterialsSeoul National UniversitySeoulRepublic of Korea Lotte Chemical R&D Center DaejeonRepublic of Korea Department of Chemical Engineering Hanyang UniversitySeoulRepublic of Korea School of Chemical Engineering and Material Science Chung‐Ang UniversitySeoulRepublic of Korea

To attain a circular carbon economy and resolve CO_(2) electroreduction technology obstacles,single‐atom catalysts(SACs)have emerged as a logical option for electrocatalysis because of their extraordinary catalytic *** SACs,metal–organic frameworks(MOFs)have been recognized as promising support materials because of their exceptional ability to prevent metal *** study shows that atomically dispersed Ni single atoms on a precisely engineered MOF nanosheet display a high Faradaic efficiency of approximately 100% for CO formation in H‐cell and three‐compartment microfluidic flow‐cell reactors and an excellent turnover frequency of 23,699 h^(−1),validating their intrinsic catalytic *** results suggest that crystallographic variations affect the abundant vacancy sites on the MOF nanosheets,which are linked to the evaporation of Zn‐containing organic linkers during ***,using X‐ray absorption spectroscopy and density functional theory calculations,a comprehensive investigation of the unsaturated atomic coordination environments and the underlying mechanism involving CO^(*) preadsorbed sites as initial states was possible and provided valuable insights.

关键词： 2‐dimensional material carbon dioxide reduction metal-organic frameworks single‐atom catalysts vacancy sites