Carbon Letters最新文献

Biomass-derived porous carbons are increasingly examined as practical electrode materials for supercapacitors because they combine low cost with adaptable structural features. In this study, black-eyed pea peels, a widely available agricultural residue, is used as the precursor and activated with either K₂CO₃ or KMnO₄, which resulted in noticeable differences in pore development and electrochemical behaviour. Thermogravimetric analysis showed that the derived carbons retain good thermal stability. X-ray diffraction, X-ray photoelectron spectroscopy, and Raman measurements indicated a largely disordered carbon framework with only limited graphitic domains, offering numerous defect sites that support ion adsorption. Scanning electron microscopy revealed thin carbon walls and an ultra-microporous network with a considerable proportion of mesopores, which was further supported by Brunauer–Emmett–Teller analysis. The material obtained using K₂CO₃ delivered a capacitance of around 236 F g^− 1, sustained almost 99% of its performance during long cycling, and responded better at high current. The KMnO₄ activated sample exhibited additional pseudocapacitive contributions but lower stability. Overall, these results underline the role of activation chemistry in governing pore architecture and surface functionality and show that agricultural residues can be transformed into viable electrode materials for high-power energy-storage applications.

Although porous SiC ceramics have been applied across various industries, their high cost limits broader and more extensive utilization. In this study, porous reaction-formed SiC ceramics were fabricated using waste fabric and discarded silicon wafer waste as carbon and silicon sources, respectively. Three types of porous carbon preforms with ∼77% porosity were prepared by varying the initial ratios of waste fabric and furfuryl alcohol. The influence of waste fabric content on the microstructure and mechanical properties of the porous carbon preform was systematically investigated. Higher waste fabric content led to the formation of a more uniform, network-like microstructure, free of large, dense carbon residues. This microstructural refinement enhanced the conversion efficiency of carbon to SiC during the infiltration process. The optimal performance was achieved with a preform containing 75 wt% waste fabric, infiltrated with molten silicon at 1500 °C for 1 h. The resulting SiC ceramics exhibited a compressive strength of 51.4 MPa at 59.4% porosity, surpassing that of porous reaction-bonded SiC ceramics. This approach, involving molten Si infiltration into waste-derived, low-cost carbon preforms, offers a cost-effective and environmentally sustainable route for fabricating high-performance porous carbon structures and porous SiC ceramics for diverse industrial applications.

Carbon nanotubes (CNTs), as one-dimensional carbon nanomaterials, exhibit exceptional electrical conductivity, mechanical strength, and chemical stability, making them highly suitable for applications in energy storage and wearable devices. Despite Floating catalyst chemical vapor deposition (FCCVD) is a scalable, one-step method capable of fabricating CNT aerogels, fibers, and sheets. A key advantage of FCCVD lies in its tunability of CNT properties such as aspect ratio, crystallinity, wall number, and chirality during synthesis, which are critical parameters for optimizing electrochemical performance. However, as-synthesized CNTs typically contain impurities such as residual catalysts, graphitic impurities and amorphous carbon, necessitating post-synthesis purification and functionalization to improve their compatibility with polymer matrices and composite systems. CNTs are widely used as active materials and conductive networks in batteries and supercapacitors, contributing to enhanced both energy and power density. Despite these advantages, CNT based devices still face challenges including variability in properties, cost, scalability, and integration issues such as structural non-uniformity, and inconsistent assemblies that limit cycle life and reproducibility. Various purification and functionalization strategies have been developed to improve the CNT quality for device integration. This review outlines FCCVD-based CNT synthesis, purification and functionalization methods, and highlights the critical roles CNTs play in advancing next-generation lithium-ion batteries and supercapacitors.

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Porous hard carbon has recently gained attention as an anode material for KIB because of its superior potassium ion storage performance. In this study, an efficient method for producing polyethylene-based hollow porous carbon is presented. Partial sulfonation was applied, and the porosity of the resulting carbon material was regulated by the sulfonation time. A hollow structure with the high specific surface area of 173.3 m²/g was achieved via partial sulfonation and carbonization without additional activation. Using polyethylene (PE)-based porous carbon as an anode material for KIB, a high specific discharge capacity of 187 mAh/g and excellent rate capability  at 1000 mA/g were achieved. Moreover, potassium-ion storage mechanisms were identified and compared with those of non-porous PE-based carbon anodes. This study provides an effective method for preparing porous PE-based carbon with superior energy storage performance.

Owing to its excellent properties, graphite shows great potential for applications in engineering. However, the removal mechanism of brittle materials results in the formation of randomly distributed craters of varying sizes on the machined surface of graphite during machining. The difficult machining characteristics lead to the importance of studying the cutting mechanism of graphite. In this paper, the cutting process of graphite has been numerically simulated by the finite element method. In numerical simulations, the accuracy of the simulation results depends largely on the accuracy of the selected intrinsic model parameters. To determine the parameters of the Johnson‒Holmquist II (JH-2) constitutive model, this paper presents systematic mechanical testing of graphite materials. The compressive and impact strengths of graphite were found to be 142.17 MPa and 133.6 MPa via quasistatic compression and Hopkinson compression rod experiments, respectively, and the damage patterns of graphite were obtained. The constant HEL of the equation in the Hugoniot state was measured to be 1.056 GPa using plate impact tests. Finally, the experimental data obtained were combined with the theoretical derivation to finalize the parameters of the JH-2 model. To ensure the reliability of the model parameters, the cutting simulation results were compared with the actual experimental results.

Waste materials have become a promising source for producing carbonaceous materials, that can be utilized in energy storage system as well as in wide range of applications. The growing accumulation of waste tires presents significant environmental challenges, but also offers an opportunity to convert them into valuable carbon-based materials for energy storage applications. In the present study, a facile and scalable approach has been demonstrated to synthesizing self-doped, heteroatom-enriched carbon from waste tires via catalytic pyrolysis followed by hydrochloric acid (HCl) leaching. The resulting chemically treated carbon (CTC), derived from pyrolytic carbon char (CC), exhibits a porous microstructure and is doped with multiple heteroatoms, as confirmed through comprehensive characterization techniques, including X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and N₂ adsorption desorption Brunauer-Emmett–Teller (BET) isotherm. The electrochemical performance of both CC and CTC was evaluated in a symmetric two-electrode configuration using 1 M tetraethylammonium tetrafluoroborate (TEABF₄) in acetonitrile (ACN) organic electrolyte. The CTC exhibited significantly enhanced capacitive performance compared to CC, achieving a specific capacitance of 346.67 Fg^− 1 at 1 A g^− 1, alongside excellent energy density (39 Wh kg^− 1) and power density (450 W kg^− 1). Notably, the CTC retained 90% of its initial capacitance after 10,000 charge-discharge cycles at a current density of 10 A g^− 1, demonstrating excellent cycling stability. This work presents a facile, and sustainable approach for repurposing waste tires into high-performance electrode materials for supercapacitors.

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Aiming to create electrocatalysts for the hydrogen evolution reaction (HER), this work looks at the synthesis and characterization of transition metal sulfides (FeS, NiS, and MoS2) supported on CMK-8 type mesoporous carbon (MC) materials. The synthesized catalysts were characterized using N2 adsorption-desorption, X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), scanning electron microscope (SEM), and electrochemical performance tests such as linear scanning voltammetry (LSV), cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). All the synthesized catalysts were compatible with the Type-IV isotherm, which indicates the mesoporous structure and MC exhibited the highest surface area of ​​1157 m2/g. While the crystal structure of the Ni-S catalyst consisted of NiSO4.6H2O and NiS2 compounds, only peaks belonging to FeS2 and MoS2 crystals were observed in the Fe-S and Mo-S catalysts, respectively. In MC supported catalysts, it is predominantly in the amorphous carbon structure belonging to the support. Further improvement of the support-catalyst interaction is required, as evidenced by the notably high overpotential of 460 mV displayed by the Ni-S@MC catalyst and the much lower overpotential of 232 mV by Ni-S. The charge transfer resistance values were found to vary, according to impedance analysis. Ni-S demonstrated the lowest resistances (18.5 Ω at -0.3 V), highlighting its better electron transfer capabilities over other catalysts. The larger overpotentials from MC’s enhanced surface area underscore the trade-off between maximizing kinetics and preserving low energy barriers. These results highlight the possibilities and difficulties of employing metal sulfides on MC substrates for effective and long-lasting HER applications.

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Sugar-derived carbon fibers (SBCFs) emerge as a promising next-generation sustainable material due to their biomass origin, cost-effectiveness, and superior strength-to-weight ratio. However, industrial adoption remains hindered by inefficient optimization of complex pre-carbonization processes. Here, we present a machine learning (ML)-driven framework to address this challenge, integrating experimental data to establish quantitative correlations between pre-carbonization parameters (temperature, dwell time) and mechanical performance. Gradient Boosted Decision Trees (GBDT) achieved superior predictive accuracy (R² = 0.857 for tensile strength), enabling efficient identification of optimal conditions: 220 °C pre-carbonization temperature with 100 min dwell time. Experimental validation confirmed a 5.60% tensile strength enhancement over baseline protocols. Optimized protocols yield fibers with 874 MPa tensile strength and 76 GPa modulus, with an average diameter of 28 μm. This machine learning-driven methodology not only advances SBCF manufacturing but also establishes a generalizable paradigm for accelerating functional material development.

A dual-analyte electrochemical platform was developed using RuS₂-Fe nanodots and a multi-walled carbon nanotube (MWCNT) incorporated RuS₂-Fe composite (RuS₂/MWCNT-Fe) composites for the sensitive detection of xylazine hydrochloride (XLZ) and erythrosine B (ERY). Both the RuS₂-Fe nanodots and RuS₂/MWCNT-Fe composites were synthesized via hydrothermal method then used to develop sensors via drop casting on glassy carbon electrodes (GCE). The RuS₂-Fe nanodots and RuS₂/MWCNT-Fe composites greatly improved the redox capacity of the interfacial region and electron transfer to the surface of the electrodes. Theoretical density functional calculations also validated experimental evidence of charge redistribution within the iron centres of the complex, narrowing of the band gap, and preferential adsorption of both XLZ and ERY. In particular, RuS₂-Fe/GCE exhibited unprecedented electrodes within the context of the XLZ analyte, achieving 0.249 nM LOD and a linear range of 0.005–2500 µM. In contrasting work, RuS₂/MWCNT-Fe composites electrode obtained 36 nM LOD and ranged 0.05–100 µM towards ERY. Careful analysis of electrochemical impedance and control studies utilizing pristine RuS₂ with variable Fe concentrations, alongside extensive durability analysis, elucidated the significant influence of trace Fe concentrations on catalytic activity enhancements. In the context of recent reports on MXene, CNT, and oxide hybrids, the RuS₂/MWCNT-Fe system still exhibited ample confirmations on charge transfer resistance and sensitivity. Proposed oxidation mechanisms illustrate the influence of iron on interfacial electron-proton coupling. The versatility of RuS₂-Fe nanodots set as a carbon-based electrocatalyst has now been expanded to the dual detection of veterinary sedatives and food colorants. Such a development can be translated as a new stride toward the development of portable food safety, pharmaceutical quality control, and clinical diagnostics devices.

In this study, we upcycled waste polyethylene (PE) foam into a hard carbon anode material for sodium-ion batteries (SIBs) via sulfonation and subsequent carbonization. Following an optimized sulfonation process (100 °C, 24 h), the sample carbonized at 800℃ (PE_C800) demonstrated the best performance, showing a high reversible capacity of 180 mAh·g^− 1 at 0.1 C, excellent rate capability, and long-term cycling stability (93.3% retention after 100 cycles). Structural analysis revealed this sample possessed a hierarchical porous structure and an interlayer spacing (0.388 nm), suitable for Na⁺ insertion. Through cyclic voltammetry (CV) kinetic analysis and ex-situ Raman spectroscopy, the sodium storage was determined to follow an “adsorption-insertion model”, combining surface adsorption and interlayer insertion. This work presents a practical route for converting plastic waste into high performance energy storage materials.