Carbon Letters最新文献

To explore the heating characteristics of activated carbon in a microwave field, the effects of microwave irradiation power, the radius and physical properties of activated carbon, and a symmetrical waveguide on the heating characteristics of activated carbon in a microwave field were studied by experiments and simulation. This study distinguishes itself from previous works by focusing on high-power microwave heating (up to 800 W) and providing a comprehensive analysis of key parameters such as radius, thermal conductivity, magnetic conductivity, and dielectric constant. Additionally, the use of symmetrical waveguides and their impact on heating efficiency represents a novel contribution to the field of microwave-assisted flue gas desulfurization. According to the results, with the increase in microwave irradiation power, the heating rate of activated carbon in the microwave field increases, and the final temperature also rises. Waveguides significantly influence the heating characteristics of activated carbon. When multiple waveguides act on the same microwave field, electromagnetic waves interfere with each other and affect the distribution and intensity of the electromagnetic field. With an increase in the imaginary part of the relative permittivity, the real part of the relative magnetic permeability, and the thermal conductivity of the heated material, the heating characteristics of activated carbon in the microwave field are improved. This study provides a theoretical model for the heating characteristics and temperature distribution of activated carbon in a microwave field under high irradiation power.

Water contamination caused by heavy metal pollutants from industrial activities remains a pressing environmental concern. This study reports the development of a novel carbon paste electrode (CPE) modified with ethylenediaminetetraacetic acid (EDTA), polyvinyl alcohol (PVA), and multi-walled carbon nanotubes (MWCNTs) using a mechanochemical method for the electrochemical detection of Cu(II) ions. The modified electrode was thoroughly characterized to evaluate its functional groups, morphology, crystallinity, elemental composition, and electrochemical properties. Electrochemical measurements were performed using cyclic voltammetry (CV) and square-wave anodic stripping voltammetry (SWASV) under optimized conditions in 0.1 M NH₄Cl at pH 5. The EDTA/PVA/MWCNT-CPE exhibited a low detection limit (0.0457 µM), a wide linear range (0.1–2.7 µM), and excellent reproducibility (RSD = 0.51%), repeatability (RSD = 0.43%), and stability (95% retention after six days). Selectivity tests demonstrated high recovery for Cu(II) (99.7%) and Hg(II) (99.89%) with minimal interference. This simple, cost-effective sensor offers high sensitivity and selectivity, making it a promising candidate for Cu(II) detection in environmental monitoring applications.

This study investigates the sustainable synthesis of biobased graphene (BG) derived from coconut husk waste and its application in eco-friendly water-based drilling muds (WBM). The BG was prepared through thermal exfoliation of lignin and utilized as a fluid loss additive, while benzimidazole (BI) was incorporated to serve as a corrosion inhibitor. To optimize performance, the Taguchi method was combined with Grey Relational Analysis (GRA), targeting three key parameters: viscosity, fluid loss, and corrosion resistance. Structural characterization revealed that BG synthesized at 1000 °C exhibited improved graphitic ordering, with an average flake diameter of around 20 nm and an interlayer spacing (d-spacing) of 3.49 Å. In terms of performance, incorporating 0.5 wt% BG reduced fluid loss by 50%, while 5 wt% BI delivered an impressive corrosion inhibition efficiency of 96.9%. The optimal mud formulation was achieved using 0.5 wt% BG, 5 wt% BI, 60 min of mixing time, and 8 wt% bentonite. Altogether, this work highlights a sustainable pathway for drilling fluid formulation by valorizing agricultural waste and minimizing additive loadings—without compromising on performance or environmental compatibility.

This work focuses on the development of an innovative detection platform utilizing a novel ternary composite of transition metal dichalcogenide ruthenium disulfide (RuS₂), tungsten trioxide (WO₃) and multi-walled carbon nanotubes (RuS₂/WO₃/MWCNT) for the purpose of detecting hazardous pollutant catechol. An augmented current response for catechol was acquired by the synergetic effect of ternary composite. The unique combination of these materials enhances the sensor’s electrochemical performance due to the excellent catalytic activity of RuS₂, redox properties of WO₃ and the high surface area and electrical conductivity provided by MWCNTs. Morphological and structural characterizations were done using different characterization methods. The increased electroactive surface area and fast electron transfer rate resulted by the adaptation of the working electrode leads to the development of a sensitive and selective sensor. The RuS₂/WO₃/MWCNT modified electrode exhibited remarkable sensitivity towards catechol determination with a wide linear detection range of 1.0–1028.0 µM and a modest low detection limit of 0.61 µM. The sensor demonstrated consistent performance in assessing the reproducibility and repeatability trials. The fabricated sensor gave reliable results and satisfactory recovery range when application on real-time sample analysis.

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Structural design and element doping are the research hotspots in the preparation of lightweight absorbers with high absorption performance and low filling rate. This study employs different temperature carbonization and etching techniques to prepare the structure of hollow nitrogen-doped carbon flowers (HNC) and evaluate their microwave absorption performance. At an ultra-low filler loading of 5 wt.%, the microwave absorption intensity of HNC-800 remains stable at -50 dB with a thickness of 3.2 mm. It is noteworthy that the HNC-800 achieved the broadest effective absorption frequency band at a matching thickness of 2 mm, with a bandwidth of 5.36 GHz (ranging from 12.4 to 17.76 GHz). Such remarkable broadband and reflection loss performance can be attributed to the synergistic effects of the hollow porous network structure, interface polarization, and dipole relaxation mechanisms. More significantly, the reduction of the radar cross-section (RCS) amounts to as much as 31.67 dB m², and it has been attested to possess excellent adsorption efficacy in practical application scenarios. HNC-800, as an absorbing material, holds potential for broad application prospects.

Bamboo charcoal has high ecological and economic value, and is a sustainable and valuable resource for the development of advanced materials such as supercapacitors and batteries. The carbon content in bamboo-based white charcoal produced in traditional Korean kiln reaches 100% when the charcoals heat treated up to 2400℃. X-ray diffraction shows that graphite begins to form at 1500℃, becomes more pronounced at 1800℃, and crystallizes into a dense turbostratic structure at 2000℃. At 2400℃, discrete graphite peaks are confirmed in d002 and d100 planes, while carbon isotope peaks disappear. Raman spectroscopy shows that graphite crystals form at 1800℃, as indicated by a clear 2D band at 2680 cm⁻¹. At 2400℃, the height of the D band at 1350 cm⁻¹ is lower than that of the G band at 1580 cm⁻¹, indicating a high degree of graphitization. The isothermal nitrogen adsorption–desorption curves show that the monolayer value of the sample decreases up to 1300℃, accompanied by a low-pressure hysteresis phenomenon. When heat-treated at 1500℃ or higher, this phenomenon disappears and the monolayer value decreases significantly, indicating the disappearance of micropores and occurrence of graphitization. After 10 min. of heat treatment at 2400℃, the specific surface area of the graphitized charcoal becomes 8.45 m²/g, similar to that of artificial graphite, which shows promising results of 217 mAh/g at a current density of 0.02 A/g for using in Lithium ion battery electrode.

Covalent organic framework (COF) membranes have emerged as promising candidates for hydrogen purification due to their tunable pore sizes and robust structures. However, achieving high selectivity and permeability simultaneously remains a challenge due to the inherent pore size distribution of COF materials. In this study, we fabricated two distinct COF membranes, TpPa-1 and TpTG_Cl, with pore sizes of 1.8 nm and 0.39 nm, respectively, using tailored synthesis methods. The TpTG_Cl membrane, synthesized via room temperature interfacial polymerization and vacuum-assisted filtration, exhibits an ultrathin nanosheet structure with an interlayer π–π stacking distance of 0.33 nm. This unique architecture, combined with its affinity for CO₂ adsorption, enables exceptional hydrogen separation performance, achieving a H₂/CO₂ selectivity of 52.5 and a H₂ permeability of 3.49 × 10^–7 mol m⁻² s⁻¹ Pa⁻¹. Molecular dynamics simulations confirmed the steric hindrance effect as the primary mechanism for the selective permeation of hydrogen. The TpTG_Cl membrane effectively sieves larger gas molecules (CO₂, N₂, CH₄, etc.) without the need for material modification or excessive membrane thickness. This study demonstrates the potential of COF membranes with tailored pore sizes for high-performance hydrogen purification and offers valuable insights for the development of advanced separation technologies.

Carbon electrodes, renowned for their excellent moisture and air stability, present a compelling alternative to unstable hole transport materials and costly metal electrodes. In carbon electrode-based perovskite solar cells (C-PSCs), organic materials play a crucial role in optimizing the surface characteristics and electrochemical performance of carbon electrodes, thereby enhancing the photoelectric conversion efficiency. By incorporating organic material additives to modulate the pore structure and surface chemistry of carbon electrodes, the processes of photon absorption and electron transport can be effectively promoted, leading to an improvement in device performance. This article comprehensively reviews the latest research progress of organic C-PSCs, covering their device structures, working principles, as well as the modification methods, advantages, and application effects of organic materials in different layers of C-PSCs. Finally, the applications of in-situ characterization and first-principles calculations in this field are briefly introduced, providing theoretical and experimental support for in-depth research. Based on the above research and analysis, optimization strategies such as enhancing charge selectivity, improving the contact between the electrode and the perovskite layer, and enhancing the quality of the perovskite layer are proposed to drive the further development of organic C-PSCs.

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Currently, carbon nanotubes (CNTs) paper (also called Buckypaper, BP) is highly promising for application in flexible electronic materials. However, the lack of flexibility and durability of BP greatly affects the comprehensive performance. Here, we propose a simple method for manufacturing a waterborne polyurethane (WPU) toughened carbon nanotube paper (WPU-BP) with excellent overall performance through vacuum filtration. In WPU-BP, as the content of WPU increased from 0 to 48.3%, the tensile strength increased from 8.08 to 16.25 MPa, and the elongation at break increased from 2.14 to 225.04%, while the conductivity decreased from 41.34 to 20.33 S/cm. The WPU-BP with the WPU content of 18.9% (CNP8) demonstrated the optimum strain sensing performance. The gauge factor of CNP8 can reach 8.57 with a response time of 145 ms. It can detect a wide range of body movements from large joint movements to slight breathing, and exhibits high stability, maintaining high stability even after 1000 cycles. In addition, CNP8 shows excellent Joule heating performance, it can reach 186.1 °C at 5 V, with heating and cooling times of only 16 and 18 s, respectively, as well as with good reproducibility. In a word, the as-prepared WPU-BP exhibits excellent both strain sensing performance and Joule heating effect, and holds significant potential for applications in heating devices and wearable sensors.

The avenue to synthesize eco-friendly and high-performing warm-white light emitting diodes (WLEDs) using quantum-dots for color conversion is challenging. Here, the graphene quantum dots (GQDs) are synthesized from Moringa oleifera leaves without the need of any organic solvents or reducing agents by a one-pot hydrothermal method and utilized for the design of efficient warm WLEDs. The photoluminescence of the obtained GQDs is found to be red-shifted as the excitation wavelength increases. This is ascribed to an excitation of multiple transitions due to various surface traps related to surface amino and oxygen functionalized groups as revealed from X-ray-photoelectron–spectroscopy and FTIR results. Three different concentrations of GQDs are embedded in polyvinyl-alcohol matrix acting as color-converters for the design of WLED devices. By increasing the GQDs concentration, the color correlated temperatures are tuned from 3804 to 2593 K and the luminous efficacy from 39.3 to 71.69 lm/W. Moreover, the chromaticity coordinates of the devices are shifted from (0.3825, 0.3665) to (0.4807, 0.4478). The brightness of the fabricated devices based on these green-GQDs are comparable with those of warm LEDs prepared from chemically synthesized graphene and carbon dots and can be suitable for indoor lighting applications.

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