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        검색결과 167

        1.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A glassy carbon electrode modified with a composite consisting of electrodeposited chitosan and carboxylated multi-walled carbon nanotubes (e-CS/MWCNTs/GCE) was used as a working electrode for simultaneous determination of dopamine (DA), serotonin (5-HT) and melatonin (MT), which were related to circadian rhythms. The electrochemical characterizations of the working electrode were carried out via electrochemical impedance spectroscopy and chronocoulometry. It was found that electrochemical modification method, that was cyclic voltammetry, may can cause continuous CS polymerization on MWCNTs surface to form a dense membrane with more active sites on the electrode, and the electrochemically active surface area of e-CS/MWCNTs/GCE obtained was about 7 times that of GCE. The electrochemical behaviour of DA, 5-HT and MT on working electrode were carried out via differential pulse voltammetry and cyclic voltammetry. The results showed that e-CS/MWCNTs/GCE solved the problem that the bare electrode could not detect three substances simultaneously, and can catalyze oxidation potential difference as low as 0.17 V of two substances reaction at the same time, indicating very good electrocatalytic activity. By optimizing the detection conditions, the sensor showed a good linear response to DA, 5-HT and MT in the range of 20-1000 μmol/L, 9-1000 μmol/L and 20-1000 μmol/L, and the detection limits were 12 μmol/L, 10 μmol/L and 22 μmol/L (S/N = 3), respectively. In addition, the proposed sensor was successfully applied to the simultaneous detection of DA, 5-HT and MT in human saliva samples.
        4,200원
        4.
        2023.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we successfully grafted chitosan (CS) onto multi-walled carbon nanotubes (MWCNTs) to enhance their properties and potential applications in the biomedical field. FTIR spectroscopy confirmed the successful covalent bonding of CS onto MWCNTs, indicated by the new absorption peak of the amide bond (–CONH–). Thermal analysis showed that the modified MWCNTs (MWCNT-CS) had significant weight loss around 260 °C, suggesting the decomposition of hydroxypropyl chitosan, and confirming its presence in the nanocomposite. SEM images revealed that CS grafting improved the dispersibility of MWCNTs, a property crucial for their use as nanofillers in polymers. Moreover, the micro-tensile bond strength of dentin surface increased with increasing MWCNT-CS concentrations, indicating the potential of MWCNT-CS as a pretreatment for dentin bonding. After simulated aging, the bond strength remained significantly higher for MWCNT-CS groups compared to those without pretreatment. In biocompatibility assessment using the MTT assay, MWCNT-CS showed higher cell viability than MWCNT, suggesting improved biocompatibility after CS modification. The results of this study suggest that CS-modified MWCNTs could be promising materials for applications in dentin bonding, dentin mineralization, bone scaffolding, implants, and drug delivery systems.
        4,000원
        5.
        2023.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Flexible supercapacitors (FS) are ideal as power backups for upcoming stretchable electronics due to their high power density and good mechanical compliance. However, lacking technology for FS mass manufacturing is still a significant obstacle. The present study describes a novel method for preparing FS based on reduced graphene oxide (RGO) using the N+ plasma technique, in which N+ reduces graphene oxide on the surface of a cotton/polyester substrate. The effect of aloe vera (AV) as a natural reducing & capping agent and carbon nanotubes (CNT) as nanoconductors on the electrochemical performance of the electrodes is studied. FESEM and XPS were employed to investigate the electrodes' structural and chemical composition of electrodes. The galvanostatic charge–discharge curves of electrodes revealed the enhancement of the electrochemical activity of the as-prepared electrode upon additions of AV and CNT. The areal capacitance of the RGO, RGO/AV, and RGO/ AV/CNT supercapacitors at 5 mV/s was 511, 1244.5, and 1879 mF/cm2, respectively. The RGO electrode showed capacitive retention of 80.9% after 2000 cycles enhanced to 89.7% and 92% for RGO/AV and RGO/AV/CNT electrodes, respectively. The equivalent series resistance of the RGO electrode was 126.28 Ω, decreased to 56.62 and 40.06 Ω for RGO/AV and RGO/ AV/CNT electrodes, respectively.
        4,000원
        6.
        2023.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Nitrogen and phosphorous dual-doped carbon nanotubes (N,P/CNT) have been grown in a single-step direct synthesis process by CVD method using iron-loaded mesoporous SBA-15 support, as an electrode material for the energy storage device. For comparison, pristine nanotubes, nitrogen and phosphorous individually doped nanotubes were also prepared. The basic characterization studies clarify the formation of nanotubes and the elemental mapping tells about the presence of the dopant. Under three-electrode investigations, N,P/CNT produced a maximum specific capacitance of about 358.2 F/g at 0.5 A/g current density. The electrochemical performance of N,P/CNT was further extended by fabricating as a symmetric supercapacitor device, which delivers 108.6 F/g of specific capacitance for 0.5 A/g with 15 Wh/kg energy density and 250 W/kg power density. The observed energy efficiency of the device was 92.3%. The capacitance retention and coulombic efficiency were 96.2% and 90.6%, respectively, calculated over 5000 charge–discharge cycles.
        4,500원
        7.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, gold nanoparticles (AuNPs) were synthesised using green chemistry to decorate multi-walled carbon nanotubes (MWCNTs) made from walnut shells transmission electron microscopy, field-emission scanning electron microscopy (FESEM), atomic force microscopy and fourier transforms infrared spectroscopy were used to diagnose MWCNTs and AuNPs. MWCNT-COOAu, MWCNT-COO and MWCNT-Au were diagnosed by Raman, energy dispersive X-ray analysis and FESEM. The effect of AuNPs, MWCNT-COO, MWCNT-COOAu and MWCNT-Au on pure and serum alkaline phosphatase (ALP) enzyme activity was studied in vitro using the enzyme-substrate 4-nitrophenyl disodium orthophosphate. For pure enzymes, Vmax slightly increased as the concentration of MWCNT-Au, MWCNT-COOAu and MWCNTCOO increased, whereas the Vmax values decreased as the concentration of AuNPs increased. The inhibition type for all NPs varied. For serum ALP enzyme, the Vmax values for Au-based NPs decreased as the concentration of NPs increased. The Vmax values exceeded the standard value at the concentrations of 25, 50 and 75 ppm for MWCNT-Au and MWCNT-COOAu, whereas the Vmax values increased over the standard value for all concentrations of AuNPs.
        4,500원
        8.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Single-walled carbon nanotube (SWNT) has gained significant interest as a transducer in various electrochemical sensing devices due to their unique structure, compatibility with biomolecules, and excellent electronic properties. As-prepared SWNTs are usually a mixture of semiconducting and metallic ones. Despite of the higher content of semiconducting components in mixed SWNTs, metallic properties are predominantly expressed due to the bundling issue of the SWNT during the fabrication process, limiting the applicability to bio-transistor application. Here, we present a multi-scale semiconducting electronic film of SWNTs as a transducing platform for electrochemical field-effect-transistor (eFET) suitable for the sensitive detection of subtle biological modulation. A genetically engineered filamentous M13 phage showing strong binding affinity toward SWNTs on its body surface was used as a biological material, allowing us to fabricate a large-scale transparent semiconducting nanocomposite. As the relative ratio of SWNT to M13 phage decreases, the on–off ratio of SWNT electronic film increases by 1200%. To show broad applicability, the multi-scale SWNT nanomesh-based eFET is applied for monitoring a variety of biological reactions in association with enzymes, aptamers, and even cyanobacteria. The biomimetic electronic material system with the capability of transducing biological responses at a large scale over a broad dynamic range holds excellent promise for biosensors, biofuel cells, and environment monitoring.
        4,000원
        9.
        2023.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Mass production of high-quality carbon nanotubes (CNTs) remains a challenge, requiring the development of new wetimpregnated catalyst suitable for the catalytic chemical vapor deposition (CCVD) of CNTs in a fluidized bed reactor. For the successful development of a new catalyst, a highly robust system to synthesize CNTs must be established. Here, we systematically investigated the robustness of CNT synthesis by CCVD using a wet-impregnated catalyst. We statistically tested four factors that could potentially affect the robustness of CNT synthesis system, focusing on carbon yield and IG/ID. First, we tested the effect of vacuum baking before CNT growth. F test and CV equality test concluded that vacuum baking recipe did not significantly reduce the variability of the CNT synthesis. Second, we tested the batch-to-batch variation of catalysts. The results of t test and one-way analysis of variance indicate that there is significant difference in carbon yield and IG/ID among catalysts from different batches. Third, we confirmed that there is spatial non-uniformity of wet-impregnated catalysts within a batch when they are produced in large scale. Finally, we developed a multi-step heating recipe to mitigate the temperature overshooting during the CNT synthesis. The multi-step recipe increased the mean of carbon yield, but did not influence the variability of CNT synthesis. We believe that our research can contribute to the establishment of a robust CNT synthesis system and development of new wet-impregnated catalysts.
        4,000원
        11.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To investigate the effect of the catalyst and metal–support interaction on the methane decomposition behavior and physical properties of the produced carbon, catalytic decomposition of methane (CDM) was studied using Ni/SiO2 catalysts with different metal–support interactions (synthesized based on the presence or absence of urea). During catalyst synthesis, the addition of urea led to uniform and stable precipitation of the Ni metal precursor on the SiO2 support to produce Ni-phyllosilicates that enhanced the metal–support interaction. The resulting catalyst upon reduction showed the formation of uniform Ni0 particles (< 10 nm) that were smaller than those of a catalyst prepared using a conventional impregnation method (~ 80 nm). The growth mechanisms of methane-decomposition-derived carbon nanotubes was base growth or tip growth according to the metal–support interaction of the catalysts synthesized with and without urea, respectively. As a result, the catalyst with Ni-phyllosilicates resulting from the addition of urea induced highly dispersed and strongly interacting Ni0 active sites and produced carbon nanotubes with a small and uniform diameter via the base-growth mechanism. Considering the results, such a Ni-phyllosilicate-based catalyst are expected to be suitable for industrial base grown carbon nanotube production and application since as-synthesized carbon nanotubes can be easily harvested and the catalyst can be regenerated without being consumed during carbon nanotube extraction process.
        4,300원
        12.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The inclusion of conductive carbon materials into lithium-ion batteries (LIBs) is essential for constructing an electrical network of electrodes. Considering the demand for cells in electric vehicles (e.g., higher energy density and lower cell cost), the replacement of the currently used carbon black with carbon nanotubes (CNTs) seems inevitable. This review discusses how CNTs can contribute to the development of advanced LIBs for EVs. First, the reason for choosing CNTs as a conducting agent for the cathode is discussed in terms of energy density. Second, the reinforcing effect of CNTs on the anode is described with respect to the choice of silicon as the active material. Third, the development of water-based cathode fabrication as well as dry electrode fabrication with aid of CNTs is discussed. Fourth, three technical hurdles, that is, the price, dispersion issue, and entrapped metal impurities, for widespread use of CNTs in LIBs are discussed.
        4,000원
        13.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Owing to their simplicity and ease of synthesis, carbon nanotubes (CNTs) have captivated attention of researchers. Many engineering applications have investigated the new features of nanostructured carbon nanotubes, such as large surface area, stiffness and durability. CNTs have opened up new opportunities for environmental improvement, pollution management and application in a variety of fields. Multiple types of pollution are produced as a result of population growth, urbanization and industrialization. CNTs are used to solve a variety of challenges, including environmental difficulties, water pollution, biomedical applications, and so on. It becomes an unavoidable present and future material. Different applications of CNTs have been presented in this review paper. CNTs are potential material having number of uses, including water purification, drug delivery, preservatives, catalysis, genetic engineering and artificial implants which are reviewed in this review article. This paper is presenting an explicit and systematic progress of CNTs for water treatment, medicinal uses drug delivery, artificial implants and so on, and a multitude of CNT applications in broad disciplines and their purification methods have been covered. The issues related to synthesis technologies, purification technology, bio-medicinal application and catalytic property of CNTs within the framework of different engineering applications and environmental impact are discussed in this study.
        7,800원
        14.
        2023.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Lead sulfide ( PbS ) nanocrystals anchored on nitrogen-doped multiwalled carbon nanotubes ( CNx ) have been synthesized employing an environmentally friendly and inexpensive wet chemistry process. CNx∕PbS composites have been examined by scanning electron microscopy, X-ray diffraction and Raman spectroscopy. Theorical ab initio calculations have been developed to determine the samples structural, morphological and optical properties to explain the experimental evidences. The PbS nanoparticles exhibit of 4 nm to 27 nm particle size with a face-centered cubic crystal structure and are homogeneously distributed along the carbon nanotubes. The nitrogen-doped CNTs acts as binding sites for the PbS clusters as ab initio theoretical study suggests.
        4,000원
        15.
        2023.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Hydroxyl radical (OH radical) is the most harmful free radical amongst the Reactive Oxygen Species (ROS) responsible for numerous diseases of DNA damage like mutagenesis, carcinogenesis and ageing. Therefore, it is important to find a suitable scavenger for OH radical. In the present contribution, we aim to investigate the ability of pristine armchair-SWCNT and B/N/P-doped armchair-SWCNT to scavenge OH radicals using DFT calculations. The calculations reveal that the B/Pdoped armchair-SWCNTs can act as a better scavenger for OH radical compared to pristine armchair-SWCNT but N-doped armchair-SWCNT does not act as a better scavenger for OH radical compared to pristine armchair-SWCNT. Furthermore, the developed scavenger is examined in terms of large-scale availability, biocompatibility, conductivity, stability and reactivity. For both in vivo and in vitro studies, the work is found to useful for enhancing SWCNT as a free radical scavenger.
        4,800원
        16.
        2023.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Hydrogen energy is a promising source of renewable and clean energy for various industries, such as chemical, automobile, and energy industries. Electrolysis of water is one of the basic methods for the production of hydrogen energy. However, the high overpotential of the oxygen evolution reaction (OER) in water electrolysis has hindered the effective production of hydrogen using this method. Thus, the development of high-efficiency non-precious metal-based electrocatalysts for OER is extremely significant. In this study, we adopted a one-step hydrothermal method to fabricate Ni-based catalysts with N/Sdual doped graphene oxide/carbon nanotube (GO/CNT) supports using thiourea ( CH4N2S) and urea as the S source and the N source. It was observed that the amount of thiourea utilized in the synthesis of the catalyst affected the morphology, composition, and the electrochemical properties of the catalyst. For a GO/CNT-to-thiourea mass ratio of 1:10, the catalyst exhibited the highest activity, where the OER overpotential was 320 mV at a current density of 10 mA/cm2. This was attributed to the high specific surface area, high conductivity, and fast electron transport channels of the N/S-dual doped GO/ CNT composite. Furthermore, sulfurization of the Ni particles to form nickel sulfide played a significant role in enhancing the catalytic performance.
        4,000원
        17.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We report the use of face mask materials as a carbon precursor for the synthesis of multi- and single-walled carbon nanotubes (CNTs) in an open-loop chemical recycling process. Novel surgical mask precursors were suspended in toluene and injected into a chemical vapor deposition reactor previously optimized for CNT production using liquid injection. The CNTs were collected and characterized using resonant Raman spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) before being turned into fibrils that were tested for electrical conductance. Once confirmed and repeated for statistical accuracy, a CNT-based Ethernet cable was manufactured and tested using iPerf3 for uplink and downlink speeds exceeding broadband standards worldwide. Radial breathing modes from Raman spectroscopy indicate single walled CNTs (SWCNTs) with diameters ranging from 0.8 to 1.55 nm and this matches well with TEM observations of SWCNTs with 1.5 nm diameter. This work pushes the horizon of feedstocks useful for CNT and SWCNT production in particular; this work demonstrates upcycling of materials fated for disposal into materials with positive net value and plenty of real-world applications.
        4,000원
        18.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Different materials have been shown to "catalyze" carbon nanotube (CNT) growth in chemical vapor deposition (CVD) when they become nano-sized particles. Catalysts, which act as a kind of "seed" for CNT growth, show two types of behavior in the CVD method; precipitation of carbon atoms from the eutectic alloy forming a kind of alloy with carbon; the fact that the catalyst remains as a solid phase and forms a carbon surface layer during the CVD process. This study examines the relationship between the iron-group and non-iron-group catalyst types and the catalyst concentration and growth time of CVD-based CNT growth via emphasizing growth mechanisms. The novelty of this work is to compare and evaluate the effects of catalyst type, concentration, and growth time, which are three critical CVD parameters, on the final nanotube morphology. It was utilized five different catalysts ( Fe2O3, Fe3O4, Nb2O5, Au, and Pt), three different growth durations (3, 5, and 7 min), and three different catalyst concentrations (2, 4, and 6 wt%) to explore the morphological differences on CNT synthesis by CVD under the same process parameters. The results demonstrated that catalyst type is the most influential parameter in CVD-based CNT synthesis, while catalyst concentration and growth time are indispensable elements for the uniformity and small diameter in the final morphology.
        4,800원
        19.
        2022.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        An electrical double-layer capacitor is fabricated with biomass-derived activated carbon (AC) and multi-walled carbon nanotubes (MWCNTs), which are synthesized from Pongamia pinnata fruit shell and its seed oil, respectively. The activated carbon is produced by the chemical activation process at varying carbonization temperatures from 600 to 900 °C for 5 h at a rate of 10 min in an N2 atmosphere. The surface area of activated carbon and MWCNTs is 1170 m2 g− 1 and 216 m2 g− 1, respectively. The total pore volumes of activated carbon and MWCNTs are 1.51 cm3 g− 1 and 0.5907 cm3 g− 1, respectively. The as-prepared AC and MWCNTs are characterized by surface area analysis Brunner–Emmett–Teller method (BET), X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopic analysis, field emission scanning electron microscopy, high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy. The electrochemical performances of AC-AC, MWCNTs-MWCNTs and AC-MWCNTs (25:75) symmetric electrodes are studied by cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy. The AC-MWCNTs (25:75) single electrode performance is also studied in two different electrolytes, such as 0.5 M Na2SO4 and 0.5 M H2SO4. The fabricated AC-MWCNTs (25:75) symmetric supercapacitor cell exhibits excellent electrochemical performance in 0.5 M Na2SO4. It shows a specific capacitance of 55.51 Fg− 1, energy density 4.852 Wh Kg− 1 and power density of 199.18 W Kg− 1 at a current density of 1 Ag− 1 in the voltage window of 0–1.8 V. The AC-AC and AC-MWCNTs (25:75) symmetric supercapacitor electrodes show outstanding performance.
        6,300원
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