Carbon Letters最新文献

Electrochemical capacitors predominantly rely on porous carbon materials with high specific surface areas; however, precise control over pore size distribution remains a critical challenge in optimizing electrode performance. In this study, we present a two-step activation strategy for fabricating hierarchical porous carbon derived from Monoon longifolium seed biomass (HPC-MS), which enables systematic tuning of the pore architecture. The optimized carbon material demonstrated a high specific surface area of 898 m² g⁻¹ with well-developed hierarchical porosity. When evaluated in a two-electrode symmetric configuration, the HPC-MS electrode delivered an impressive specific capacitance of 368 F g⁻¹ at a current density of 1 A g⁻¹, along with outstanding cycling stability, retaining 97.2% of its capacitance after 5000 charge–discharge cycles. These results demonstrate the potential of waste biomass as a sustainable carbon source and provide a promising pathway for developing high-performance supercapacitors through rational pore structure engineering.

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The synthesis of the hierarchical porous carbon derived from Monoon longifolium seed (HPC-MS) biomass involves a two-step process comprising chemical activation and carbonization. The activation step promotes the development of a hierarchical pore network featuring interconnected micropores, mesopores, and macropores. This multiscale architecture facilitates efficient ion transport, enhances electrolyte accessibility, and significantly improves the electrochemical performance of the resulting electrode material for high-performance supercapacitor.

A facile and scalable thermal exfoliation–deposition method was developed to synthesize 2D g-C₃N₄/CuO heterojunction photocatalysts with controlled morphology. By tuning the g-C₃N₄ loading, the carbon nitride morphology transitions from dispersed two-dimensional (2D) nanosheets to bulk-like three-dimensional (3D) structures, which significantly influences the optical properties and photocatalytic performance of the composites. The photocatalysts were evaluated under solar irradiation for the degradation of carbendazim (CBZ) and methylene blue (MB). The g-C₃N₄/CuO composites exhibited significantly enhanced photocatalytic activity compared to individual g-C₃N₄ and CuO, due to efficient charge separation at the heterojunction. Optimal photocatalytic performance was achieved at 15% g-C₃N₄ loading, achieving up to 98% degradation of CBZ and MB within 80 min. Radical scavenging experiments identified superoxide radicals (O₂•⁻) as the primary reactive species. The 15% g-C₃N₄/CuO composite also showed excellent stability over multiple cycles. These results highligh the importance of interfacial engineering and compositional optimization for efficient, durable, and scalable solar-driven photocatalysts.

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Thermoelectric materials enable direct heat-to-electricity conversion. They have gained increasing interest in sustainable and wearable energy-harvesting systems. However, progress in flexible thermoelectric devices remains limited by the shortage of high-performance n-type organic materials, hindering the development of efficient p–n complementary modules. Laser-induced graphene (LIG) has attracted considerable attention for thermoelectric applications due to its high electrical conductivity, scalable fabrication, and compatibility with flexible substrates. However, LIG produced from polyimide typically exhibits p-type behavior, which limits its applicability in thermoelectric modules requiring complementary n-type materials. In this study, we address this limitation by introducing a simple and scalable urea-assisted strategy to convert p-type LIG into n-type LIG through nitrogen doping during the laser-induced graphitization process. First, we have fabricated LIG by direct laser writing on polyimide and subsequently treated with 5 and 10 wt% urea solutions, followed by mild annealing. Subsequent structural and chemical characterizations confirmed effective nitrogen incorporation, dominated by graphitic-N species, while preserving the porous 3D LIG network. Thermoelectric measurements revealed enhanced electrical conductivity (up to 1120 S/m) and a clear p-to-n transition, as evidenced by negative Seebeck coefficients in urea-treated films. The optimized LIG-10 N sample delivered the highest thermoelectric performance, reaching a power factor of 0.136 µW m⁻¹ K⁻² at 60 °C. Overall, this work provides a practical route for engineering n-type LIG, supporting the development of flexible thermoelectric modules for wearable and low-power energy-harvesting applications.

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NiO/rGO nanocomposites have been synthesized by the hydrothermal method. The various amounts of prepared NiO/rGO nanocomposite were incorporated with perovskite material for fabricating the perovskite solar cells (PSCs). The structure of NiO/rGO-CH₃NH₃PbI₃ based PSC is FTO/c-TiO₂/m-TiO₂/NiO/rGO-CH₃NH₃PbI₃/Carbon. The present NiO/rGO-CH₃NH₃PbI₃ based PSC obtained a power conversion efficiency (PCE) of 15.27 % with a short circuit current (J_sc) of 23.90 mA/cm², an open circuit voltage (V_oc) of 0.94 V and a fill factor (FF) of 0.68. In contrast, the pristine CH₃NH₃PbI₃-based PSC exhibited a PCE of only 8.57 %. The incorporation of NiO/rGO enhanced the charge recombination resistance and improved the interfacial contact, which remarkably facilitated the charge separation, charge transfer and charge collection and effectively suppressed the charge recombination in the PSCs. NiO/rGO-CH₃NH₃PbI₃ based PSCs preserved 93.27 % of their initial PCE after 600 h, which endorses that the stability of the CH₃NH₃PbI₃ layer is secured from moisture by the incorporation of NiO/rGO nanocomposite. The obtained power conversion efficiency and stability of NiO/rGO-CH₃NH₃PbI₃ based PSCs is higher than that of the pristine CH₃NH₃PbI₃ based PSC. The current work clearly demonstrates that the incorporation of NiO/rGO nanocomposite improves the performance and stability of PSCs, simplifies the device fabrication process and reduces the fabrication cost.

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In this work, the novel FeNi-LDH/NF and (Fe-Ni)O_x/NF were prepared using facile hydrothermal and calcination methods. The electrocatalyst FeNi-LDH/NF ((Fe-Ni)O_x/NF) exhibits excellent HER catalytic activity, and produced an overpotential of 147 (210) mV at 10 mA cm⁻² with a small Tafel value of 97 (100) mV dec⁻¹ in 1.0 M KOH electrolyte. Due to the high-density active centers exposed on the surface of FeNi-based hydroxides, their electrical conductivity, and the synergistic effect between the metals, the catalytic activity of FeNi-based hydroxides is superior to that of FeNi-based oxides. The overall experimental findings showcase a feasible approach for exploring the potential of the nonprecious metal-based FeNi-LDH/NF ((Fe-Ni)O_x/NF) nanoelectrocatalyst towards alkaline HER.

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The growing global water crisis necessitates innovative solutions that are both cost-effective and environmentally sustainable. Atmospheric water harvesting (AWH) has emerged as a promising avenue of research to address this pressing challenge. Here, we present a novel approach that re-purposes low-value petroleum feedstocks for AWH through their conversion to porous carbon (PC). Utilizing a potassium carbonate-assisted carbonization process, we develop PC from heavy and light cycle oils, and vacuum residue. While all sources yield materials with near superhydrophilic surfaces, only the cycle oils produce PC with high surface area and micoporous architectures. These engineered carbons demonstrate great water adsorption capacities of up to 23 wt% at 60% relative humidity (RH), surpassing commercially available carbon materials.

Achieving a superior combination of strength and electrical conductivity in carbon nanotubes (CNTs) reinforced Cu matrix composites remains a significant challenge, primarily due to CNTs agglomeration and poor interfacial bonding. This study introduces a systematic integrated processing route combining Cu powder morphology control with a two-stage ball milling process. By rationally integrating validated powder processing steps and optimizing key process parameters, we directly address the long-standing strength–conductivity trade-off in CNTs/Cu composites. Dendritic Cu powder was first transformed into flake-shaped particles via pre-ball milling, increasing its specific surface area to enhance subsequent CNTs adhesion. A secondary ball milling step was applied to the CNTs/Cu flake mixture, effectively embedding CNTs into the matrix. Compared to composites prepared using dendritic or flake-shaped Cu powder alone, the composite subjected to the two-stage ball milling process exhibited a more homogeneous CNTs dispersion, reduced agglomeration, and enhanced interfacial bonding. Consequently, this optimized composite demonstrated a superior balance of tensile strength and electrical conductivity, offering a scalable pathway for fabricating high-performance CNTs/Cu composites.

Expanding dye use elevates ecological risks by increasing dye-contaminated wastewater discharge. Cationic dyes resist removal owing to high stability and toxicity, but activated carbon adsorption remains an efficient and economical treatment. In this study, we examine methylene blue (MB) removal using activated carbon prepared from petroleum pitch through KOH activation, followed by nitrogen plasma treatment for 5, 10, 15, and 30 min. To characterize the surface chemistry and porosity of the nitrogen-functionalized carbon, we employed elemental analysis (EA), X-ray photoelectron spectroscopy (XPS), and N₂ adsorption–desorption (Brunauer-Emmett-Teller, BET) measurements. Batch adsorption tests were conducted at MB concentrations of 100, 200, 300, 400, and 500 mg L⁻¹. The nitrogen plasma treatment increased the surface nitrogen content (from 0.44% to 1.94% depending on the treatment conditions) and enhanced MB adsorption performance. Equilibrium data were fitted using the Langmuir and Freundlich isotherm models; the Freundlich model showed a better correlation, indicating multilayer adsorption on a heterogeneous surface and suggesting that plasma-introduced nitrogen sites provided additional adsorption sites.

The present work demonstrates a comprehensive experimental and molecular modeling study of fixed bed adsorption of CO₂ over commercial activated carbon (AC-RBAA-3). The AC-RBAA-3 was characterized using Brunauer-Emmett-Teller (BET) surface area analyzer, Scanning Electron Microscope (SEM), and Raman analyses. The lower temperature (or 298 K) remained best for CO₂ capture over AC-RBAA-3 and allowed robust adsorption up to 1140 s compared to the higher temperatures (328 K; 878 s). The breakthrough profile of CO₂ decreased with increasing feed gas flow rate because of lower residence time, especially at higher flow rates. Interestingly, the lower initial CO₂ concentration showed a better breakthrough profile compared to the higher one. The maximum CO₂ uptake of 1.18 mmol/g was accomplished at 298 K with a flow feed rate of 5 L/min and C_in=5%. The minimal length of mass transfer zone (L_MTZ) nearly equal to 1.77 cm was determined with an improved capacity utilization factor (i.e., 0.965 at 298 K). The maximum usable bed height was 23.39 cm, with an improved efficiency of 93.57%. Additionally, the experimental results were verified by Density Functional Theory (DFT) calculations, describing that CO₂ adsorbed weakly on perfect graphite surfaces, CO₂ adsorbed weakly mainly via van der Waals interaction, with the binding energy of -21.5 kJ/mol, while the adsorption energy of CO₂ in the pores of graphite is exothermic. However, at the amorphous site of the activated carbon, CO₂ adsorbed more strongly with the energy of -41.5 kJ/mol, suggesting that this should be considered for further enhancement in the CO₂ adsorption efficiency of activated carbon. Charge density plots revealed that the charge transfer between CO₂ and the amorphous carbon sites was the factor contributing to the enhanced affinity of CO₂ on activated carbon, justifying its effectiveness in capturing CO₂ obtained in our experiments.

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