fnctId=bbs,fnctNo=3389 29 건 게시물 검색 제목 작성자 공통(상단고정) 공지 게시글 게시글 리스트 김민규 교수님 연구실(Energy Storage Mateirals) 작성자 우수한 조회수 43 첨부파일 0 제목 : A design guideline of graphite/silicon composite electrode for extremely fast charging Li ion batteries 저널 : Energy Storage Mateirals링크 : https://www.sciencedirect.com/science/article/pii/S2405829724005658Achieving extremely fast charging (XFC) capabilities is critical for the development of lithium-ion batteries (LIBs) for electric vehicles (EVs). However, conventional LIBs with graphite anodes face challenges with lithiation at high charging rates, often resulting in Li plating. Incorporating silicon (Si) with graphite to form graphite/Si composite electrodes presents a potential solution, but the detailed design rules for these composite electrodes are not yet well understood. Here, we systematically investigate the impact of varying Si content on the fast-charging behaviors of graphite/Si composite electrodes. Through electrochemical analysis, in-situ X-ray diffraction (XRD), and a newly developed reaction dynamics analysis cell, our research demonstrates that the lithiation reaction proceeds inhomogeneously and becomes increasingly concentrated on the Si component as the charging rate increases. Based on these findings, a physics-based model further explores the effects of Si properties and electrode design on XFC ability, proposing guidelines for designing advanced graphite/Si composite electrodes to achieve robust XFC abilities in LIBs. 박성진 교수님 연구실(Nanoscale) 작성자 우수한 조회수 34 첨부파일 0 제목 : Atomically dispersed Co-based species containing electron withdrawing groups for electrocatalytic oxygen reduction reactions저널 : Nanoscale링크 : https://doi.org/10.1039/D4NR01635ASingle-atom-based catalysts are a promising catalytic system with advantages of molecular catalysts and conductive supports. In this work, a new hybrid material (CoF/NG) is produced using a low-temperature reaction between an organometallic complex (Co(C5HF6O2)2) (CoF) and N-doped reduced graphene oxide (NG). CoF contains electron-withdrawing CF3 groups in the ligand around a Co atom. Microscopic and chemical characterization studies reveal that Co-based species are coordinated to N sites of NG and molecularly dispersed on the surface of NG. The CoF/NG hybrid shows improved electrocatalytic properties, such as onset (0.91 V) and half-wave (0.80 V) potentials, for the electrochemical oxygen reduction reaction (ORR) relative to the NG material. Control experiments reveal that Co (N)graphene acts as a major active species for ORR. CoF/NG shows moderate cycling durability and microscopy measurements of CoF/NG-after-cycle indicate the formation of nanoparticles after electrocatalytic measurements. All experimental data support that the incorporation of Co-based organometallic species containing electron-withdrawing groups around the metal center onto the graphene-based networks improves the electrocatalytic ORR performance but diminishes the electrocatalytic stability of the active species. 강동원 교수님 연구실(Advanced Engineering Materials) 작성자 우수한 조회수 89 첨부파일 0 제목 : Metal-Organic Frameworks for Emerging Thermoelectric Applications저널 : Advanced Engineering Materials링크 : https://doi.org/10.1002/adem.202400825Metal-organic frameworks (MOFs) have emerged as highly promising porous materials for various applications due to their exceptional porosity, large surface areas, and tunable functional properties. Recently, MOFs have garnered attention as potential thermoelectric materials that convert heat into electricity, offering environmentally friendly energy solutions. This perspective highlights recent research on thermoelectric MOFs and MOF-based composites, exploring synthesis methods and strategies for enhancing their thermoelectric performance and future directions. 김명웅 교수님 연구실(ACS Applied Materials & Interfaces) 작성자 우수한 조회수 79 첨부파일 0 제목 : Supramolecular Association of a Block Copolymer via Strong Hydrogen Bonding to Form Self-Healable Ionogels저널 : ACS Applied Materials Interfaces링크 : https://doi.org/10.1021/acsami.4c09988The drive to enhance the operational durability and reliability of stretchable and wearable electronic and electrochemical devices has led to the exploration of self-healing materials that can recover from both physical and functional failures. In the present study, we fabricated a self-healable solid polymer electrolyte, referred to as an ionogel, using reversible hydrogen bonding between the ureidopyrimidone units of a block copolymer (BCP) network swollen in an ionic liquid (IL). The BCP consisted of poly(styrene-b-(methyl acrylate-r-ureidopyrimidone methacrylate)) [poly(S-b-(MA-r-UPyMA)], with the IL-phobic polystyrene forming micellar cores that were interconnected via intercorona hydrogen bonding between the ureidopyrimidone units. By precisely regulating the molecular weight and the composition of the hydrogen-bondable motifs, the mechanical, electrical, and self-healing characteristics of the ionogel were systematically evaluated. The resulting ionogel samples exhibited suitable stretchability, ionic conductivity, and room-temperature self-healability due to reversible hydrogen bonding. To highlight the applicability of the self-healing ionogel as a high-capacitance gate insulator, an electrolyte-gated transistor (EGT) was fabricated using a poly(3-hexylthiophene-2,5-diyl) semiconductor, and the performance of the EGT was fully recovered from a complete cut without any external stimuli. 박성진 교수님 연구실 (EcoEnergy) 작성자 우수한 조회수 230 첨부파일 0 제목 : Co(O)4(N)-type single-atom-based catalysts and ligand-driven modulation of electrocatalytic properties for reducing oxygen molecules저널 : EcoEnergy링크 : https://doi.org/10.1002/ece2.27Single-atom-based catalysts are intriguing electrocatalytic platforms that combine the advantages of molecular catalysts and conductive carbon-based materials. In this work, hybrids (Co-NrGO-1 and Co-NrGO-2) were generated by wet-reactions between organometallic complexes (Co(CH3COO)2 and Co[CH3(CH2)3CH(C2H5)COO]2, respectively) and N-doped reduced graphene oxide (NrGO) at25℃. Various characterizations revealed the formation of atomically dispersed Co(O)4(N) species in Co-NrGO-2. Density functional theory (DFT) calculations explained the effect of the aliphatic C7 group in Co2 on the formation processes. The Co-NrGO-2 hybrid showed excellent catalytic performance, such as onset (0.94V) and half-wave (0.83V) potentials, for electrochemical oxygen reduction reaction (ORR). Co-NrGO-2 outperformed Co-NrGO-1, which was explained by more back donation to the antibonding orbitals of O2 from electron-rich aliphatic groups. DFT calculations support this feature, with mechanistic investigations showing favored ORR reactions and facile breakage of double bonds in O2. 박성진 교수님 연구실 (Chemical Engineering Journal) 작성자 우수한 조회수 148 첨부파일 0 제목 : Thesynthesis and key features of 3D carbon nitrides (C3N4) used for CO2 photoreduction저널 : Chemical Engineering Journal링크 : https://doi.org/10.1016/j.cej.2024.150213 CO2concentrationintheatmospherehasreachedanall-timehigh,leadingtoglobalwarming.ThescientificcommunityhassuggestedphotocatalyticCO2reductionasareliablemethodtoreduceCO2concentrationandproducecleanenergy.Carbonnitride-basedphotocatalystshavecaughtcommunityattentionduetotheiractivityinvisiblelight,easyandinexpensivesynthesis,andhigherreductionpotentialthanrequiredforCO2.Morphologyengineeringisoneofthewaystoenhancephotocatalyticproperties,as3Dcarbonnitrides(C3N4)havelargersurfaceareas,higherlightharvestingability,andslowerchargecarrierrecombinationthanthebulkform.Thisreviewarticlesummarizesthesynthesisandcharacteristicsof3DC3N4-basedphotocatalystsreportedforCO2photoreduction.3DC3N4-basedphotocatalystshaveexecutedanexcellentperformanceinthefieldofCO2photoreduction.Thisreviewwillaidinunderstandingtheuseof3DC3N4inCO2photoreduction,therelatedpresentstudies,andresearchgapsthatwillbeofserviceinfutureresearch. 강동원 교수님 연구실(J. Am. Chem. Soc.) 작성자 우수한 조회수 209 첨부파일 0 제목 : Simultaneous Protonation and Metalation of a Porphyrin Covalent Organic Framework Enhance Photodynamic Therapy저널 : Journal of the American Chemical Society링크 : https://doi.org/10.1021/jacs.4c03519Covalent organic frameworks (COFs) have been explored for photodynamic therapy (PDT) of cancer, but their antitumor efficacy is lim-ited by excited state quenching and low reactive oxygen species generation efficiency. Herein, we report a simultaneous protonation and metalation strategy to significantly enhance the PDT efficacy of a nanoscale two-dimensional imine-linked porphyrin-COF. The neutral and unmetalated porphyrin-COF (Ptp) and the protonated and metalated porphyrin-COF (Ptp-Fe) were synthesized via imine conden-sation between 5,10,15,20-tetrakis(4-aminophenyl)porphyrin and teraphthalaldehyde in the absence and presence of ferric chloride, re-spectively. The presence of ferric chloride generated both doubly protonated and Fe3+-coordinated porphyrin units, which redshifted and increased the Q band absorption and disrupted exciton migration to prevent excited state quenching, respectively. Under light irradia-tion, rapid energy transfer from protonated porphyrins to Fe3+-coordinated porphyrins in Ptp-Fe enabled 1O2 and hydroxyl radical gener-ation via type II and type I PDT processes. Ptp-Fe also catalyzed the conversion of hydrogen peroxide to hydroxy radical through a pho-to-enhanced Fenton-like reaction under slightly acidic condition and light illumination. As a result, Ptp-Fe-mediated PDT exhibited much higher cytotoxicity than Ptp-mediated PDT on CT26 and 4T1 cancer cells. Ptp-Fe-mediated PDT afforded potent antitumor effi-cacy in subcutaneous CT26 murine colon cancer and orthotopic 4T1 murine triple-negative breast tumors and prevented metastasis of 4T1 breast cancer to the lungs. This work underscores the role of fine-tuning the molecular structures of COFs in significantly enhancing their PDT efficacy. 양상희/김명웅 교수님연구실 (ACS Applied Polymer Materials) 작성자 우수한 조회수 216 첨부파일 0 제목 : Chemical Regulating Cationic Polymerization of Difunctional Epoxy Resin through Structural Variations of the Thermal Initiator저널 : ACS Applied Polymer Materials링크 : https://doi.org/10.1021/acsapm.4c00956The cationic polymerization of epoxides facilitates the rapid cross-linking of epoxy resins, increasing their effectiveness for packaging and adhesive applications and efficiency of their manufacturing. However, the reaction conditions, such as temperature, should be adjusted, and the polymerization behaviors should be modulated to meet the demands for resin products and, consequently, broaden the application of epoxy resins. This study investigated the influence of structural variations in sulfonium-type initiators on thermal cationic polymerization. We prepared 47 different thermally activatable initiators by combining four designed sulfonium-type cations with varying aromatic ring substituents and 13 anions categorized by their central charge-bearing atoms. We evaluated the polymerization and cross-linking activities of the initiators with bis[4-(glycidyloxy)phenyl]methane. The structural variations of the anions had a larger influence on polymerization than that of the cations. Specifically, polymerization required higher thermal energy and reaction temperatures with stronger ionic interactions between the anion and cation. The delocalization of negative or positive charges by the substituted groups on both ions and steric hindrance affected the ionic interactions. Finally, various initiators facilitated fine-tuning of the initiation temperature to 53 139 C for epoxy resin production. The thermal behaviors were analyzed using differential scanning calorimetry, including the kick-off temperature, peak temperature, and reaction enthalpy. Therefore, we elucidated cationic polymerization based on the chemical structure of the initiator, which can be used to achieve a high-performance, on-demand curable epoxy-based system. 김명웅 교수님 연구실(ACS Appl. Mater. Interfaces) 작성자 강동원 조회수 250 첨부파일 0 제목: Chemical Structure Physicochemical Property Relationships of Copolymers Utilizable for Negative-Tone Photoimaging via Chemical Amplification저널: ACS Applied Materials Interfaces링크: https://doi.org/10.1021/acsami.3c19522We demonstrate an understanding of different physicochemical properties of copolymers induced by systematic changes in their structural parameters, i.e., the chemical structure of the comonomer unit, composition, molecular weight, and dispersity. The terpolymers were designed to be implemented in a chemically amplified resist (CAR) to form negative-tone patterns. With two basic repeating units of 4-hydroxystyrene and 2-ethyl-2-methacryloxyadamantane as monomers for conventional CARs, the pendant group of the third methacrylate comonomer was varied from aromatic, aliphatic lactone to lactone rings to modulate the interaction capability of the copolymer chains with n-butyl acetate, which is a negative-tone developer. Along with these structures, the monomer composition, molecular weight, and dispersity were also controlled. Physicochemical properties of the synthesized copolymers having controlled structures, i.e., dissolution behaviors and quantified Hansen solubility parameters, surface wetting characteristics, and surface roughness, which can be important properties affecting patterning capability in high-resolution lithography, were explored. Furthermore, the feasibility to use experimentally determined Hansen solubility parameters of the copolymers for the prediction of pattern formation using a coarse-grained model was assessed. Our comprehensive studies on the correlation of the structural parameters of the copolymers with final properties offer fundamental avenues to attain effective designs of the complex CAR system toward the lithographic process to achieve a sub-10 nm dimension, which is close to a single-chain dimension. 조동규 교수님 연구실(J. Am. Chem. Soc.) 작성자 강동원 조회수 260 첨부파일 0 제목: Effects of Electron-Withdrawing and Electron-Donating Groups on Aromaticity in Cyclic Conjugated Polyenes저널: Journal of the American Chemical Society링크: https://pubs.acs.org/doi/10.1021/jacs.3c14390Determining the aromaticity of various fluorinated benzenes is challenging as easily obtained experimental aromaticity [ (Houter Hinner)] necessitates the chemical shifts of inner and outer protons. This issue was addressed in porphyrinoids by replacing the electron-withdrawing (E.W.) groups at the meso-positions of porphyrins and allyliporphyrins. Electronic effects on aromaticity in porphyrinoids have not been thoroughly examined in the literature. In porphyrins, the effect of E.W. groups is minimal, making it difficult to establish a clear relationship between the aromaticity strength and E.W. groups. Conversely, in allyliporphyrins, stronger E.W. groups, such as indandione (IND) derivatives, significantly reduce the aromaticity of the parent structure. The IND derivatives disrupted the aromatic pathway of allyliporphyrin more effectively than those attached to porphyrins. This is attributed to the absence of -carbons in allyliporphyrins. The effect of electron-donating (E.D.) groups on porphyrins and allyliporphyrins was further investigated. Contrary to the initial assumption that the E.D. groups might enhance aromaticity owing to their ability to increase electron density, as the strength of the E.D. groups increased, the aromaticity of the porphyrinoids decreased. Despite the modest reduction in aromaticity, any form of electron perturbation reduces aromaticity. The aromaticity of various fluorinated benzenes is expected to parallel our observations of porphyrinoids as representative aromatic polyenes.참고: https://plaza.inha.ac.kr/bbs/kr/11/36972/artclView.do 처음 13 1 2 3 다음 페이지 끝
