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  신동하 교수님 연구실(Water Reaserch)

  작성자

  우수한

  조회수

  94

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  0

  제목 : Metal-free AAO membranes function as both filters and Raman enhacers for the analysis of nanoplastics 저널 : Water Reaserch링크 : https://www.sciencedirect.com/science/article/pii/S0043135424019432Nanoplastics (NPs) are growing concerns for health and the environment, being widely distributed across marine, freshwater, air, and biological systems. Analyzing NPs in real environmental samples requires pretreatment, which has traditionally been complex and often leads to underestimation in actual samples, creating a gap between real-world conditions and research findings. In this study, we propose using anodic aluminum oxide (AAO) membrane as a direct Raman substrate for particles on a filter, achieving complete recovery during separation and concentration while simplifying the pretreatment stages. Moreover, our study introduces AAO itself, without any metal coating, as a normal Raman spectroscopy substrate with strong Raman signal enhancement for NPs and an ultra-flat surface for rapid analysis. By using AAO with nanometer-sized pores, we effectively detected standard polystyrene spherical particles on the AAO membrane down to 200 nm. Our investigation extended to irregular NPs containing PP, PE, PET, PS, PMMA, and PLA, confirming the reliability of this approach. Our results suggest that employing an AAO membrane with dual functionality as both a filter and a Raman substrate effectively serves as a cost-effective, rapid, simple, and accurate tool for NP analysis in complex environments.
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  신동하 교수님 연구실(Sensors and Actuators B: Chemical)

  작성자

  우수한

  조회수

  76

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  0

  제목 : Quantification of auto-photobleaching effects during Raman measurements for microplastic detection저널 : Sensors and Actuators B: Chemical링크 : https://www.sciencedirect.com/science/article/pii/S0925400524014321Fluorescence interference is a common issue when analyzing microplastics with Raman spectroscopy due to the presence of coloring substances such as organic dyes. Various methods have been attempted to mitigate this fluorescent background, with photobleaching being widely used. However, there has been a lack of quantitative studies on the extent of photobleaching at the single-particle level. In this study, we quantitatively analyzed the photobleaching effect by varying microplastic size, dye concentration, and laser intensity, revealing the magnitude of this effect and its dependence on these parameters. Specifically, we analyzed how quickly fluorescence decreases at the single-particle level, considering the photobleaching efficiency of typical organic dyes. Our results show that, under realistic Raman measurement conditions, careful adjustment of these variables can lead to rapid photobleaching of microplastics below a certain size, thereby sufficiently eliminating fluorescence background issues. These insights are crucial for optimizing experimental protocols and streamlining the detection of small colored microplastics in real environmental samples using Raman spectroscopy.
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  신동하 교수님 연구실(Environmental Science & Technology)

  작성자

  우수한

  조회수

  36

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  0

  제목 : Direct Observation of Particle-To-Particle Variability in Ambient Aerosol pH Using a Novel Analytical Approach Based on Surface-Enhanced Raman Spectroscopy저널 : Environmental Science Technology링크 : https://pubs.acs.org/doi/full/10.1021/acs.est.4c00220The pH of atmospheric aerosols is a key characteristic that profoundly influences their impacts on climate change, human health, and ecosystems. Despite widely performed aerosol pH research, determining the pH levels of individual atmospheric aerosol particles has been a challenge. This study presents a novel analytical technique that utilizes surface-enhanced Raman spectroscopy to assess the pH of individual ambient PM2.5 10 aerosol particles in conjunction with examining their hygroscopic behavior, morphology, and elemental compositions. The results revealed a substantial pH variation among simultaneously collected aerosol particles, ranging from 3.3 to 5.7. This variability is likely related to each particle s unique reaction and aging states. The extensive particle-to-particle pH variability suggests that atmospheric aerosols present at the same time and location can exhibit diverse reactivities, reaction pathways, phase equilibria, and phase separation properties. This pioneering study paves the way for in-depth investigations into particle-to-particle variability, size dependency, and detailed spatial and temporal variations of aerosol pH, thus deepening our understanding of atmospheric chemistry and its environmental implications.
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  신동하 교수님 연구실(Analytical chemistry)

  작성자

  우수한

  조회수

  33

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  0

  제목 : Fast Detection and Classification of Microplastics below 10 m Using CNN with Raman spectroscopy저널 : Analytical chemistry링크 : https://pubs.acs.org/doi/full/10.1021/acs.analchem.4c00823In light of the growing awareness regarding the ubiquitous presence of microplastics (MPs) in our environment, recent efforts have been made to integrate Artificial Intelligence (AI) technology into MP detection. Among spectroscopic techniques, Raman spectroscopy is preferred for the detection of MP particles measuring less than 10 m, as it overcomes the diffraction limitations encountered in Fourier transform infrared (FTIR). However, Raman spectroscopy s inherent limitation is its low scattering cross section, which often results in prolonged data collection times during practical sample measurements. In this study, we implemented a convolutional neural network (CNN) model alongside a tailored data interpolation strategy to expedite data collection for MP particles within the 1 10 m range. Remarkably, we achieved the classification of plastic types for individual particles with a mere 0.4 s of exposure time, reaching an approximate confidence level of 85.47( 5.00)%. We postulate that the result significantly accelerates the aggregation of microplastic distribution data in diverse scenarios, contributing to the development of a comprehensive global microplastic map.
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  박성진 교수님 연구실(Nanoscale)

  작성자

  우수한

  조회수

  189

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  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.
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  강동원 교수님 연구실(Advanced Engineering Materials)

  작성자

  우수한

  조회수

  172

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  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.
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  김명웅 교수님 연구실(ACS Applied Materials & Interfaces)

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  우수한

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  168

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  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.
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  박성진 교수님 연구실 (EcoEnergy)

  작성자

  우수한

  조회수

  302

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  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.
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  박성진 교수님 연구실 (Chemical Engineering Journal)

  작성자

  우수한

  조회수

  203

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  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.
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  강동원 교수님 연구실(J. Am. Chem. Soc.)

  작성자

  우수한

  조회수

  284

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  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.