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High-power and long-life supercapacitive performance of hierarchical, 3-D urchin-like W18049 nanostructure electrodes

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Nano Research 2016年第3期9卷 633-643页

作者： Sangbaek Park Hyun-Woo Shim chan Woo Lee Hee Jo Song jae-chan kim Dong-Wan kim Department of Materials Science and Engineering Seoul National University Seoul 151-744 Republic of Korea School of Civil Environmental and Architectural Engineering Korea University Seou1136-713 Republic of Korea

We report the facile, one-pot synthesis of 3-D urchin-like W18O49 nanostructures （U-WO） via a simple solvothermal approach. An excellent supercapacitive performance was achieved by the U-WO because of its large Brunauer-Emmett- Teller （BET） specific surface area （ca. 123 m2.g-1） and unique morphological and structural features. The U-WO electrodes not only exhibit a high rate-capability with a specific capacitance （Csp） of -235 F·g-1 at a current density of 20 A.g-1, but also superior long-life performance for 1,000 cycles, and even up to 7,000 cycles, showing -176 F·g-1 at a high current density of 40 A.g-1.

关键词： hierarchical structure W18O49 high-power long cycle life supercapacitor

Tailoring uniform γ-MnO2 nanosheets on highly conductive three-dimensional current collectors for high-performance supercapacitor electrodes

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Nano Research 2015年第3期8卷 990-1004页

作者： Sangbaek Park Hyun-Woo Shim chan Woo Lee Hee Jo Song Ik jae Park jae-chan kim Kug Sun Hong Dong-Wan kim Department of Materials Science and Engineering Seoul National University Seou1151-744 R. O. Korea School of Civil Environmental and Architectural Engineering Korea University Seou1136-713 R. O. Korea

Recent efforts have focused on the fabrication and application of three- dimensional （3-D） nanoarchitecture electrodes, which can exhibit excellent electrochemical performance. Herein, a novel strategy towards the design and synthesis of size- and thickness-tunable two-dimensional （2-D） MnO2 nanosheets on highly conductive one-dimensional （l-D） backbone arrays has been developed via a facile, one-step enhanced chemical bath deposition （ECBD） method at a low temperature （-50 ℃）. Inclusion of an oxidizing agent, BrO3-, in the solution was crucial in controlling the heterogeneous nucleation and growth of the nanosheets, and in inducing the formation of the tailored and uniformly arranged nanosheet arrays. We fabricated supercapacitor devices based on 3-D MnO2 nanosheets with conductive Sb-doped SnO2 nanobelts as the backbone. They achieved a specific capacitance of 162 F·g-1 at an extremely high current density of 20 A·g% and good cycling stability that shows a capacitance retention of -92% of its initial value, along with a coulombic efficiency of almost 100% after 5,000 cycles in an aqueous solution of I M Na2SO4. The results were attributed to the unique hierarchical structures, which provided a short diffusion path of electrolyte ions by means of the 2-D sheets and direct electrical connections to the current collector by 1-D arrays as well as the prevention of aggregation by virtue of the well-aligned 3-D structure.

关键词： nanosheets manganese oxide chemical bath deposition SnO2 nanobelts supercapacitor

Tetradentate Pt(Ⅱ)complex as a singlet exciton sensitizing host for highly efficient green fluorescent organic light-emitting diodes

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Science China Materials 2024年第8期67卷 2618-2627页

作者： Unhyeok Jo Seung chan kim chan Hee Ryu Kang Mun Lee jae-Min kim Jun Yeob Lee School of Chemical Engineering Sungkyunkwan University2066Seobu-roJangan-guSuwon-siGyeonggi-do 16419Republic of Korea Department of Chemistry Institute for Molecular Science and Fusion TechnologyKangwon National UniversityChuncheonGangwon 24341Republic of Korea Department of Advanced Materials Engineering Chung-Ang University4726Seodong-daeroDaedeok-myeonAnseong-siGyeonggi-do 17546Republic of Korea SKKU Advanced Institute of Nano Technology Sungkyunkwan University2066Seobu-roJangan-guSuwonGyeonggi 16419Republic of Korea SKKU Institute of Energy Science and Technology Sungkyunkwan University2066Seobu-roJangan-guSuwonGyeonggi 16419Republic of Korea

Efficient green fluorescent organic light-emitting diodes were designed with a phosphorescent metal complex as a singlet exciton sensitizing host(SESH)for achieving high efficiency and low efficiency roll-off through exciton and polaron *** Pt(Ⅱ)complex(Pt-Trz)possessing a tetradentate ligand with a bulky blocking group not only suppresses the severe formation of excimer or dimer itself but also transfers radiative excitons to fluorescent dopant *** SESH assisted fluorescence(SESHF)device with Pt-Trz as the host exhibits the maximum external quantum efficiency of 13.3%and a lower efficiency roll-off compared with exciplex host device which is a general approach for harvesting triplet *** exciton dynamics modeling unravels that the SESHF device effectively utilizes triplet excitons in the host by intersystem crossing and resonance energy transfer from the triplet state of the host to the singlet state of the terminal *** quenching rates of the SESHF device are reduced by 11 times for triplet-triplet annihilation and 1.8 times for tripletpolaron annihilation compared with the exciplex device,which demonstrates that Pt-Trz could be a platform to be used as an efficient host for fluorophores.

关键词： singlet annihilation polaron

Dual in-situ observation of tribochemical and morphological evolution of single-layer WS_(2)and multi-layer WS_(2)/C coatings

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Friction 2024年第7期12卷 1580-1598页

作者： Yuzhen LIU jae-Ho HAN Shusheng XU Young chan JUNG Dae-Eun kim State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China Department of Mechanical Engineering Yonsei UniversitySeoul03722Republic of Korea Shandong Laboratory of Advanced Materials and Green Manufacturing at Yantai Yantai 264000China Yantai Zhongke Research Institute of Advanced Materials and Green Chemical Engineering Yantai 264000China

The outstanding tribological performance of transition metal dichalcogenides(TMDs)is attributed to their unique sandwich microstructure and low interlayer shear *** advantageous structure allows TMDs to demonstrate exceptional friction reduction ***,the incorporation of TMDs and amorphous carbon(a-C)in multi-layer structures shows excellent potential for further enhancing tribological and anti-oxidation *** carbon,known for its high ductility,chemical inertness,and excellent wear resistance,significantly contributes to the overall performance of these multi-layer *** gain an in-depth understanding of the tribological mechanism and evolution of TMDs’multi-layer coatings,a dual in-situ analysis was carried out using a tribometer equipped with a 3D laser microscope and a Raman *** innovative approach allowed for a comprehensive evolution of the tribological,topographical,and tribochemical characteristics of both single-layer WS_(2)and multi-layer WS_(2)/C coatings in real *** findings from the dual in-situ tribotest revealed distinct failure characteristics between the single-layer WS_(2)coating and the multi-layer WS_(2)/C *** single-layer WS_(2)coating predominantly experienced failure due to mechanical removal,whereas a combination of mechanical removal and tribochemistry primarily influenced the failure of the multi-layer WS_(2)/C *** tribological evolution process of these two coatings can be classified into four stages on the basis of their tribological behavior:the running-in stage,stable friction stage,re-deposition stage,and lubrication failure *** stage represents a distinct phase in the tribological behavior of the coatings and contributes to our understanding of their behavior during sliding.

关键词： In-situ analysis multi-layer coating tribology tribochemistry

Nanoparticle Exsolution on Perovskite Oxides:Insights into Mechanism,Characteristics and Novel Strategies

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Nano-Micro Letters 2024年第2期16卷 312-346页

作者： Yo Han kim Hyeongwon Jeong Bo‑Ram Won Hyejin Jeon chan‑ho Park Dayoung Park Yeeun kim Somi Lee jae‑ha Myung Department of Materials Science and Engineering Incheon National UniversityIncheon 22012Republic of Korea

Supported nanoparticles have attracted considerable attention as a promising catalyst for achieving unique properties in numerous applications,including fuel cells,chemical conversion,and *** demonstrate high activity by expanding the number of active sites,but they also intensify deactivation issues,such as agglomeration and poisoning,*** for bottomup synthesis of supported nanoparticles has emerged as a breakthrough technique to overcome limitations associated with conventional *** are uniformly exsolved from perovskite oxide supports and socketed into the oxide support by a one-step reduction *** uniformity and stability,resulting from the socketed structure,play a crucial role in the development of novel ***,tremendous research efforts have been dedicated to further controlling exsolution *** effectively address exsolution at a more precise level,understanding the underlying mechanism is *** review presents a comprehensive overview of the exsolution mechanism,with a focus on its driving force,processes,properties,and synergetic strategies,as well as new pathways for optimizing nanocatalysts in diverse applications.

关键词： Supported nanoparticle Exsolution In situ growth Mechanism Perovskite oxide Catalyst

Construction of a High‑Performance Composite Solid Electrolyte Through In‑Situ Polymerization within a Self‑Supported Porous Garnet Framework

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Nano-Micro Letters 2024年第5期16卷 56-70页

作者： An‑Giang Nguyen Min‑Ho Lee jaekook kim chan‑Jin Park Department of Materials Science and Engineering Chonnam National University77 Yongbong‑roBuk‑guGwangju 61186South Korea

Composite solid electrolytes(CSEs)have emerged as promising candidates for safe and high-energy–density solid-state lithium metal batteries(SSLMBs).However,concurrently achieving exceptional ionic conductivity and interface compatibility between the electrolyte and electrode presents a significant challenge in the development of high-performance CSEs for *** overcome these challenges,we present a method involving the in-situ polymerization of a monomer within a self-supported porous Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZT)to produce the *** synergy of the continuous conductive LLZT network,well-organized polymer,and their interface can enhance the ionic conductivity of the CSE at room ***,the in-situ polymerization process can also con-struct the integration and compatibility of the solid electrolyte–solid electrode *** synthesized CSE exhibited a high ionic conductivity of 1.117 mS cm^(-1),a significant lithium transference number of 0.627,and exhibited electrochemical stability up to 5.06 V ***/Li+at 30℃.Moreover,the Li|CSE|LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cell delivered a discharge capacity of 105.1 mAh g^(-1) after 400 cycles at 0.5 C and 30℃,corresponding to a capacity retention of 61%.This methodology could be extended to a variety of ceramic,polymer electrolytes,or battery systems,thereby offering a viable strategy to improve the electrochemical properties of CSEs for high-energy–density SSLMBs.

关键词： Scalable tape-casting method Self-supported porous Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12) Composite solid electrolyte LiF-and B-rich interphase layers

In situ infrared, Raman and X-ray spectroscopy for the mechanistic understanding of hydrogen evolution reaction

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Journal of Energy Chemistry 2024年第3期90卷 632-651,I0014页

作者： Andi Haryanto Kyounghoon Jung chan Woo Lee Dong-Wan kim Department of Chemistry Kookmin UniversitySeoul 02707Republic of Korea School of Civil Environmental and Architectural EngineeringKorea UniversitySeoul 02841Republic of Korea

Hydrogen production by water reduction reactions has received considerable attention because hydrogen is considered a clean-energy carrier,key for a sustainable energy *** methods have been widely used to study the reaction mechanism of the hydrogen evolution reaction(HER),but the calculation results need to be supported by experimental results and direct evidence to confirm the mechanistic *** this review,we discuss the fundamental principles of the in situ spectroscopic strategy and a theoretical model for a mechanistic understanding of the *** addition,we investigate recent studies by in situ Fourier transform infrared(FTIR),Raman spectroscopy,and X-ray absorption spectroscopy(XAS) and cover new findings that occur at the catalyst-electrolyte interface during *** spectroscopic strategies provide practical ways to elucidate catalyst phase,reaction intermediate,catalyst-electrolyte interface,intermediate binding energy,metal valency state,and coordination environment during HER.

关键词： Hydrogen evolution reaction Infrared spectroscopy Raman spectroscopy X-ray absorption spectroscopy Reaction mechanism

Fabrication of heteroatom-doped cobalt oxide yolk–shell microsphere using recycled solution from waste materials and their excellent electrochemical properties as an anode material for lithium-ion batteries

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Rare Metals 2024年第10期43卷 4934-4947页

作者： Yeong Beom kim chanho kim Seung-Hyun kim Yun chan Kang Dongju Lee Gi Dae Park Department of Advanced Materials Engineering Chungbuk National University Department of Materials Science and Engineering Korea University Research Institute YKSintering Co.Ltd.

Heteroatom-doped transition metal oxides have attracted great attention as advanced anode materials for lithium-ion batteries due to their high theoretical capacity and superior ***,the limited resource availability has led to a substantial rise in prices for valuable metals such as Ni and Co,posing a significant challenge for their *** address this issue,recycling of these metals from waste materials have gained prominence,and particularly the recovery of Co has been mostly focused on its economic ***,we introduced a novel recycling strategy for fabrication of heteroatomdoped CoOx（comprising mainly Co3O4with a minor CoO phase） anode with a yolk–shell structure for lithium-ion batteries,by separating Co from cemented tungsten carbide *** employing a simple leaching process and subsequent spray pyrolysis,the yolk–shell structured microsphere comprising CoOxwas successfully ***,the presence of other waste metals in the leachate facilitated multi-heteroatom doping during ***,the introduction of various dopants into CoOxinduced oxygen vacancy formation,thereby enhancing the electrochemical properties of the *** a result,compared with the phase-pure （undoped） CoOxyolk–shell,the heteroatom-doped CoOxyolk–shell exhibited robust cycling stability (602 mAh·g-1for 200 cycles at 1 A·g-1) and excellent rate capability(210 mAh·g-1at 10 A·g-1).

关键词： Anode Cobalt oxide Heteroatom doping Lithium-ion batteries Recycling

Driving inward growth of lithium metal in hollow microcapsule hosts by heteroatom‐controlled nucleation

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Carbon Energy 2024年第8期6卷 262-272页

作者： Siwon kim Hong Rim Shin Ki jae kim Min‐Sik Park Jong‐Won Lee Division of Materials Science and Engineering Hanyang UniversitySeoulRepublic of Korea Department of Energy Science and Engineering Daegu Gyeongbuk Institute of Science and Technology(DGIST)DaeguRepublic of Korea Department of Energy Science Sungkyunkwan UniversitySuwonRepublic of Korea Department of Advanced Materials Engineering for Information and Electronics Integrated Education for Frontier Science and Technology(BK21 Four)Kyung Hee UniversityYonginRepublic of Korea

The application of Li metal anodes in rechargeable batteries is impeded by safety issues arising from the severe volume changes and formation of dendritic Li ***‐dimensional hollow carbon is receiving increasing attention as a host material capable of accommodating Li metal inside its cavity;however,uncontrollable and nonuniform deposition of Li remains a *** this study,we synthesize metal–organic framework‐derived carbon microcapsules with heteroatom clusters(Zn and Ag)on the capsule walls and it is demonstrated that Ag‐assisted nucleation of Li metal alters the outward‐to‐inward growth in the microcapsule ***‐incorporated microcapsules are prepared via chemical etching of zeolitic imidazole framework‐8 polyhedra and are subsequently decorated with Ag by a galvanic displacement reaction between Ag^(+)and metallic *** introduced Ag significantly reduces the energy barrier and increases the reaction rate for Li nucleation in the microcapsule host upon Li *** combined electrochemical,microstructural,and computational studies,we verify the beneficial role of Ag‐assisted Li nucleation in facilitating inward growth inside the cavity of the microcapsule host and,in turn,enhancing electrochemical *** study provides new insights into the design of reversible host materials for practical Li metal batteries.

关键词： hollow carbon hosts lithium metal batteries lithium plating metal-organic frameworks nucleation