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        검색결과 1,994

        161.
        2023.05 구독 인증기관·개인회원 무료
        Instead of using expensive platinum, carbon anodes could potentially be utilized in the process of reducing oxides in LiCl-Li2O molten salt at a high cell potential. However, this high potential leads to the generation of a mixture of anodic gases containing toxic and corrosive gases such as chlorine (Cl2), oxygen (O2), carbon monoxide (CO), and carbon dioxide (CO2). To better understand this gas mixture, we conducted real-time analyses of the gases generated on the carbon anode during the TiO reduction reaction in the molten salt at 650°C, using a MAX-300-LG gas analyzer. Our results indicate that the ratio of CO/O2/CO2/Cl2 in the gas mixture is significantly influenced by the composition of the salt, and that removing the sources of oxygen ions in the salt increases the likelihood of generating toxic and corrosive Cl2 gas.
        166.
        2023.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This study assessed the influences of fluorine introduced into DLC films on the structural and mechanical properties of the sample. In addition, the effects of the fluorine incorporation on the compressive stress in DLC films were investigated. For this purpose, fluorinated diamond-like carbon (F-DLC) films were deposited on cobalt-chromium-molybdenum substrates using radio-frequency plasma-enhanced chemical vapor. The coatings were examined by Raman scattering (RS), Attenuated total reflectance Fourier transform infrared spectroscopic analysis (ATR-FTIR), and a combination of elastic recoil detection analysis and Rutherford backscattering (ERDA-RBS). Nano-indentation tests were performed to measure hardness. Also, the residual stress of the films was calculated by the Stony equation. The ATR-FTIR analysis revealed that F was present in the amorphous matrix mainly as C-F and C-F2 groups. Based on Raman spectroscopy results, it was determined that F made the DLC films more graphitic. Additionally, it was shown that adding F into the DLC coating resulted in weaker mechanical properties and the F-DLC coating exhibited lower stress than DLC films. These effects were attributed to the replacement of strong C = C by feebler C-F bonds in the F-DLC films. F-doping decreased the hardness of the DLC from 11.5 to 8.8 GPa. In addition, with F addition, the compressive stress of the DLC sample decreased from 1 to 0.7 GPa.
        4,000원
        167.
        2023.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 농식품 소비자패널을 대상으로 설문조사를 실시하여 소비자의 소비성향에 따른 저탄소인증농산물의 소비행태를 살펴본다. 소비자의 소비성향을 윤리적 소비성향과 합리적 소비성향으로 구분하여 집단을 구성하였고, 집단 간 소비행태 차이를 분석하였다. 윤리적 소비성향 집단과 합리적 소비성향 집단 간에 저탄소 농산물 인증제의 인지도, 탄소발생 감소를 위한 노력, 탄소중립 개념 인지도 및 저탄소인증농산물에 대한 구매의도 는 유의미한 차이가 있는 것으로 나타났다. 따라서 저탄소인증농산물의 소비활성화를 위해서 합리적 소비성향을 가진 소비자들의 저탄소인증농산물 구매를 유도할 수 있는 방안을 마련할 필요가 있다.
        4,000원
        175.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Renewed interest in the reinforced carbon graphite composites has intrigued the community in the advanced materials fields. In this work, we present a simple carbon nanofibers reinforced carbon graphite composites synthetic method by incorporating mixture of coal tar pitch, synthetic graphite, pitch coke and the dispersion liquid of carbon nanofibers via liquid-phase mixing process. The impact of carbon nanofiber utilization on the microstructures and mechanical properties of carbon graphite composites are studied systematically. The covalent surface modification of carbon nanofibers effectively improves its microstructure and thereby promotes the carbon graphite composites’ dispersion behavior. We propose that a small amount of carbon nanofibers could promote the carbonization process of carbon graphite composites, facilitating the densification of carbon graphite composites and reducing the undesired open porosity. The amount of 0.7 wt % of carbon nanofiber concentration allows the enhancement of bend and compressive strength of carbon graphite composites up to 36.50 MPa and 60.46 MPa, increased by 167.9% and 146.9% compared with the pure carbon graphite composite, respectively. Our findings can be rationalized due to the improvement in the mechanical strength of carbon graphite composites could be attributed due to pull-out of carbon nanofibers from the matrix and bridging effect across the crack pores within the matrix.
        4,200원
        176.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Biomass carbon materials with high rate capacity have great potential to boost supercapacitors with cost effective, fast charging– discharging performance and high safety requirements, yet currently suffers from a lack of targeted preparation methods. Here we propose a facile FeCl3 assisted hydrothermal carbonization strategy to prepare ultra-high rate biomass carbon from apple residues (ARs). In the preparation process, ARs were first hydrothermally carbonized into a porous precursor which embedded by Fe species, and then synchronously graphitized and activated to form biocarbon with a large special surface area (2159.3 m2 g− 1) and high degree of graphitization. The material exhibited a considerable specific capacitance of 297.5 F g− 1 at 0.5 A g− 1 and outstanding capacitance retention of 85.7% at 10 A g− 1 in 6 M KOH, and moreover, achieved an energy density of 16.2 Wh kg− 1 with the power density of 350.3 W kg− 1. After 8000 cycles, an initial capacitance of 95.2% was maintained. Our findings provide a new idea for boosting the rate capacity of carbon-based electrode materials.
        4,300원
        177.
        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
        178.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Carbon dots (CDs) were synthesized from phloroglucinol (PG) by simple heat treatment at 220–230 °C in the atmosphere without catalysts and solvents. PG-CDs heated at 220–230 °C could be completely dissolved in environmentally friendly water and exhibited a photoluminescence (PL) peak at 485 nm with 85 nm of the full width at half maximum (FWHM). The water-soluble polymer-dot-like PG-CDs were estimated to be 1.6–3.2 nm in size, and exhibited a wide range of PL wavelength at 370–630 nm. Since the PG-CDs are water-soluble materials, PG-CDs could be homogeneously mixed with a polymer such as polyvinylpyrrolidone (PVP) in water as a solvent, and PG-CDs/PVP films were prepared. The films exhibited PL characteristics that convert ultraviolet light at 350 nm to visible light above 400 nm. Thus, using PG as the raw material which has widely been produced industrially, the water-soluble fluorescent PG-CDs/PVP films could be prepared at a low cost by environmentally friendly methods.
        4,000원
        179.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Supercross-linked polymers are widely used as carbon precursor materials due to their abundant carbon sources and low cost. In this paper, a supercross-linked polymer was prepared by the solvothermal method. The supercross-linked polymer as a precursor and the PPyC-800-A was synthesized by activating this with KOH. The microstructure, structure, and electrochemical performances of porous carbon PPyC-800-A were studied at different of temperature and carbon alkali ratio. According to the results, the porous carbon PPyC-800-1:2 is mainly composed of a stack of spherical particles with a high surface area of 1427.03 m2 g− 1, an average pore diameter of 2.32 nm, and a high specific capacitance of 217.7 F g− 1 at a current density of 1.0 A g− 1 in a 6 M KOH electrolyte. It’s retention rate is 97.58% after 5000 constant current charges and discharges. With a specific capacitance decay rate of 21.91 percent, an energy density of 11.96 Wh kg− 1, and a power density of 500.0 W kg− 1, the current density rises from 1.0 A g− 1 to 10.0 A g− 1, exhibiting remarkable electrochemical properties, cycling stability, and energy production performance This study contributes experimental ideas to the field of supercrosslinked polymer-derived carbon materials and energy storage.
        4,300원
        180.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, hollow carbon spheres (HCS) have aroused great interests in the field of energy storage and conversion owing to their unique morphology, structure and other charming properties. Nevertheless, unsatisfactory electrical conductivity and relatively poor volumetric energy density caused by inevitable gaps between discrete carbon spheres greatly impede the practical application of HCS. In this work, for the first time we propose a novel dual-template strategy and successfully fabricate interconnected 3D hollow N-doped carbon network (HNCN) by a facile and scalable pyrolysis process. By systematical characterization and analysis, it can be found that HNCN is assembled by HCS and lots of mesoporous carbon. Compared to the counterparts, the obtained HNCN exhibits unique 3D interconnected architecture, larger specific surface area, hierarchical meso/macropore structure, higher structure defects, higher N doping amount and more optimized N configurations (especially for pyridinic-N and graphitic-N). As a result, these advantageous features endow HNCN with remarkably promoted electrochemical performance for supercapacitor and oxygen reduction reaction. Clearly, our proposed dual-template strategy provides a good guidance on overcoming the intrinsic shortcomings of HCS, which undoubtedly broadens their application in energy storage and conversion.
        4,000원