Carbon Letters最新文献

A hierarchical porous carbon/silicon composite material (CSCM) was prepared through KOH activation and acid leaching using coal gasification fine slag (CGFS) as the raw material. The KOH dosage, activation temperatures, and HCl acid amount were optimized. The obtained CSCMs showed higher pore volume in the range of 0.62–0.96 cm³/g, and hierarchical porous structure with V_micro./V_meso. ratio in the range of 1.54–3.31. The influence of V_micro./V_meso. ratio of CSCM on CO₂ adsorption at 0 °C was higher than that at 25 °C. Under higher specific area and pore volume, hierarchical pores with V_micro./V_meso. ratio in the range of 2.81–2.91 were benefit for CO₂ adsorption at 0 °C. The optimized CSCM demonstrated excellent CO₂ adsorption capacities of 2.96 and 4.60 mmol/g at 25 and 0 °C, respectively. CO₂ adsorption on CSCM was a heterogeneous physical process, and the cycle stability was excellent. Meanwhile, CSCM was mixed with Fe-based catalyst (Fe-K/CS) for CO₂/H₂ catalysis. The hierarchical porous structure of CSCM improved the CO₂ adsorption and H₂ adsorption around the active sites, promoting CO₂ conversion. The combination method of Fe-K and CSCM affected the distribution of CO₂ hydrogenation products, and reasonable V_micro./V_meso. ratio in CSCM effectively inhibited C–C chain growth, leading to higher olefins selectivity. The Fe-0.1K/CS-P catalyst achieved a CO₂ conversion rate of 21.6% and a C₂⁼-C₄⁼ selectivity of 47.7%. This study presented a promising approach for effectively utilizing CO₂ and for the sustainable valorization of industrial solid waste.

Graphical Abstract

It is addressed that the challenges of poor cyclic stability and low conductivity in metal–organic frameworks (MOFs) hinder their application in energy storage. Here, we synthesized binary metal MOFs through a one-step hydrothermal process, subsequently calcined to produce Co–Mn/reduced graphene oxide (rGO). This approach not only carbonized the organic framework but also enhanced its electrical conductivity and stability. Our findings demonstrated that the synergistic effects of Co and Mn within the assembled electrode resulted in remarkable performance, achieving a specific capacitance of 3558.65 F g⁻¹ at 1 A g⁻¹ and a rate capability of 1000 F g⁻¹ at 30 A g⁻¹. The Co–Mn/rGO anode in the asymmetric supercapattery exhibited a broadened operating potential window of 1.5 V, delivering an energy density of 54.65 W h kg⁻¹ at a power density of 125 W kg⁻¹, and maintaining 11.375 W h kg⁻¹ at a high power density of 12,500 W kg⁻¹. Notably, the capacitance retention rate reached 99.99% after 10,000 cycles at a current density of 10 A g⁻¹. These results suggest that the developed Co–Mn/rGO composite represents a promising candidate for advanced energy storage systems, offering both high performance and stability.

Hard carbon's excellent performance and affordability made it an ideal anode material for sodium-ion batteries. However, hard carbons derived directly from lignin often exhibit poor performance. Optimizing the synthesis process presents a valuable strategy for enhancing performance. In this study, we optimize the synthesis process to minimize costs while integrating green chemistry principles to mitigate environmental impact. Sodium lignosulfonate-formaldehyde resin-derived hard carbon is produced using a simple, low-cost pyrolysis technique involving multiple temperature stages. This process enhances the material's structural stability and electrochemical performance. X-ray diffraction (XRD) and Raman spectroscopy analysis show that higher pyrolysis temperatures lead to a distinct peak, which improves electronic conductivity. In contrast, lower temperatures result in chaotic structural formations. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) image analyses reveal that the resulting material has a porous structure with unique chemical properties. Tested for 200 cycles at a current density of 50 mA g⁻¹, the materials exhibited specific capacities of 332.24 mAh g⁻¹, 180.3 mAh g⁻¹, and 105.6 mAh g⁻¹, respectively, for LSHC-1400, LSHC-1200, and LSHC-1000. The promising results can be attributed to the unique porous structure and inherent chemical properties of the lignosulfonate precursor, which enhance the transport and storage of sodium ions. This study highlights the critical role of the synthesis method in determining the sodium storage capacity of the carbon anode in sodium-ion batteries, encouraging further exploration and optimization in this area.

Surface wetting gradient design plays a crucial role in enhancing liquid transportation in smart devices. However, achieving Janus wetting interfacial design to manage high-efficient ion transport paths remains a great challenge in textile electrodes. Herein, a porous polyvinyl alcohol (PVA) gel layer was constructed on one side of the composite electrode, while a polydimethylsiloxane (PDMS) solution was sprayed onto the opposite side of electrode to obtain an asymmetric Janus-wettability textile electrode. Furthermore, the design of asymmetric wettability gradient and multilevel structure has been facilitated to directional liquid self-drive and ion transmission in a Janus-wettability textile electrode. Compared with the charge transfer resistance (Rct) of pure PDMS superhydrophobic electrode (1.58 Ω), the Rct of Janus-wettability electrode was 1.31 Ω, which reveals that the porous PVA layer is beneficial to promoting a rapid electron transfer. For solid-state supercapacitors (FSCs) with Janus-wettability electrode, the Rct of Janus-FSCs (0.5 Ω) was reduced by 90% compared to the composite FSCs (4.6 Ω) without PDMS coating, confirming a faster ionic diffusion after the introduction of stable PDMS superhydrophobic surface for wettability gradient. Moreover, the Janus-wettability FSCs also achieved a specific energy density of 0.104 mWh cm⁻² at 1.2 mW cm⁻², and cycle stability (96.8% after 10,000 cycles). These insights demonstrate the effectiveness of interface coordination in textile electrodes for enhancing electrochemical performance.

To improve the proton conductivity of the proton exchange membranes (PEM), an amino derivative with sulfonic acid groups was used to modify graphene oxide (GO), resulting in sulfonated graphene oxide (S-GO), which was then incorporated into a perfluorinated sulfonic acid (PFSA) matrix to fabricate a PFSA/S-GO composite membranes. Elevating the doping concentration of S-GO within the composite membrane has resulted in enhanced proton conductivity, outperforming the baseline PFSA membrane across a range of temperatures. Notably, this conductivity ascended to 291.89 mS/cm when measured at 80 °C under conditions of 100% RH. Furthermore, the strong interface interaction between sulfonated graphene oxide and perfluorinated sulfonic acid polymer endowed the composite proton exchange membrane with excellent thermal stability and mechanical strength.

Bisphenol F (BPF) is a substitute agent for bisphenol A and is widely used in the production of materials such as epoxy resins and plastics. BPF accumulates in surface water because of its nonbiodegradable and recalcitrant nature, making it difficult to remove. In this study, the removal of BPF through a photocatalytic process was evaluated using zinc oxide (ZnO)/reduced graphene oxide (RGO) microspheres. A spray drying method was used to prepare the ZnO/RGO microspheres, which combine the photocatalytic efficiency of ZnO with the high electron mobility and large surface area of RGO, achieving a bandgap of 2.53 eV. Structural and morphological analyses confirmed the successful hybridization of the ZnO/RGO microsphere composite. The photocatalytic activity of the ZnO/RGO microspheres was evaluated under various light sources, with the highest degradation efficiency achieved under ultraviolet C irradiation. The optimal catalyst dosage of the ZnO/RGO microspheres was determined to be 0.1 g/L for BPF removal (BPF initial concentration = 5 mg/L). Scavenger tests revealed the dominance of superoxide radicals (O₂^·−) in the degradation process. The effects of pH (3.52–9.59), ions (Cl⁻, NO₃⁻, and SO₄²⁻), and natural organic matter were also examined to assess the practical applicability of the ZnO/RGO microsphere photocatalytic system. High pH levels and the presence of NO₃⁻ (> 10 mM) were found to enhance BPF removal. This research highlights the potential of the ZnO/RGO microspheres as efficient photocatalysts for the removal of BPF in aqueous solutions.

Efficient energy conversion technologies require cost-effective and durable catalysts for water oxidation. This study presents SnS₂/C composite synthesized via solvothermal method to enhance electrocatalytic performance in water splitting. Morphological analysis reveals that carbon incorporation disrupts the flower-like SnS₂ nanosheets, increasing active site accessibility and improving charge transfer efficiency. Three different electrolytes (KOH, PBS and H₂SO₄) are systematically employed to evaluate the material’s electrocatalytic activity comprehensively. The electrochemical tests indicate that pure SnS₂ exhibits an overpotential (η) of 410 mV at 10 mA/cm² for oxygen evolution reaction (OER) in 1 M KOH. Integration of carbon significantly lowers this value to 180 mV with a tafel slope of 103 mV/dec for SSC12 (1:2 SnS₂/C) composite. For hydrogen evolution reaction (HER) in acidic media, SSC12 achieves an η of 275 mV at 500 mA/cm² with a tafel slope of 121 mV/dec. The catalyst further demonstrates strong durability for OER in 1 M KOH but shows diminished HER activity in 0.5 M H₂SO₄. This study demonstrates the synergistic role of carbon in enhancing SnS₂ catalytic attributes, emphasizing the potential of these composites for sustainable energy conversion applications.

Graphical Abstract

Wearable thermoelectric devices offer a transformative approach to energy harvesting, providing sustainable solutions for powering next-generation technologies. In pursuit of efficient, flexible, biocompatible, and cost-effective thermoelectric materials, zinc oxide (ZnO) has emerged as a distinctive candidate due to its unique combination of favorable properties. This study explores the growth and optimization of ZnO nanorods on conductive carbon fabric (CF) using a simple microwave-assisted solvothermal technique. This method circumvents traditional complex processes that typically involve high temperatures or lengthy growth times, offering advantages such as rapid, uniform, and controllable volumetric heating. By systematically varying growth parameters, including microwave power and reaction time, we established conditions that promote the vertical alignment of ZnO nanorods, essential for enhancing thermoelectric performance. Structural and morphological analyses highlight the pivotal influence of the seed layer and growth parameters in achieving dense, uniform growth of ZnO nanorods. Interestingly, at higher microwave power levels, a transformation from nanorod structures to sheet-like morphologies was observed, likely due to Ostwald ripening, where larger particles grow at the expense of smaller ones. The optimized growth conditions for achieving superior growth and thermoelectric performance were identified as 15 min of growth at 100 W microwave power. Under these conditions, ZnO nanorods exhibited enhanced crystallinity and a higher growth rate, contributing to an improved thermoelectric power factor of 777 nW/mK² at 373 K. This work underscores the importance of precise parameter control in tailoring ZnO nanostructures for wearable thermoelectric applications and demonstrates the potential of scalable, low-cost methods to achieve high-performance energy-harvesting materials.

Capacitive deionization (CDI) represents a novel technology for the desalination and purification of seawater. Selecting the appropriate electrode material is crucial, with carbon electrodes frequently employed owing to their high specific surface area, extensive porous structure, and environmentally sustainable nature. This study presents a nitrogen-doped porous carbon, derived from household waste, which demonstrates outstanding electrochemical and desalination performance. The purified chitosan was mixed with a specific ratio of CaCO₃ and carbonized at 800 °C to produce chitosan porous carbon (CPC-T). To verify the role of the templating agent, its performance was compared with chitosan porous carbon (CPC) prepared by direct carbonization. CPC-T possesses more mesoporous structures (31.25%), shortening ion transport pathways and significantly enhancing charge transfer rates. The nitrogen-rich doping (8.65 at%) provides numerous active sites and excellent conductivity, making it highly appropriate for capacitive deionization applications. Compared to CPC prepared without a templating agent, CPC-T has a higher specific capacitance (101.5 F g⁻¹ at a scan rate of 2 mV s⁻¹) and good cycling stability. The CDI cell made from it exhibits a salt adsorption capacity (SAC) of 25.8 mg g⁻¹ for 500 mg L⁻¹ NaCl solution at an applied voltage of 1.4 V, retaining 88% capacity after 50 adsorption–desorption cycles, demonstrating excellent desalination regeneration performance. Additionally, among different concentrations of salt solutions, the CPC-T material shows the best desalination performance for the test solution at a concentration of 500 mg L⁻¹. For different solute ions, the CDI cell with this material as the electrode exhibits excellent desalination performance for Ca²⁺, with a SAC value of up to 34.02 mg g⁻¹. This is a self-doped porous carbon material that significantly outperforms traditional carbon-based materials.

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Schematic representation of the transformation of diverse biomass resources into heteroatom-doped graphene derivatives through pyrolysis, hydrothermal carbonization, and chemical/physical activation processes. These advanced carbon materials exhibit enhanced properties for applications in electrochemical energy storage systems, including batteries, supercapacitors, and fuel cells.

The growing demand for clean energy and sustainable technologies has intensified the need for efficient energy storage systems (EES) that support renewable energy integration while minimizing environmental impact. Biomass, an abundant and renewable resource, presents a cost-effective and eco-friendly pathway for producing advanced carbon materials, particularly heteroatom-doped graphene derivatives. This transformation aligns with circular economy principles by converting waste streams into high-performance materials for EES applications. This review provides a comprehensive analysis of biomass-derived heteroatom-doped graphene materials, focusing on their synthesis, properties, and applications in electrochemical energy storage systems. It addresses a critical gap in the literature by systematically examining the relationship between biomass sources, doping strategies, and their impact on graphene’s electrochemical performance. The study highlights the role of heteroatom doping such as nitrogen, sulfur, phosphorus, and boron in enhancing graphene’s structural and electronic properties. These modifications introduce active sites, improve conductivity, and facilitate ion storage and transport, resulting in superior energy density, cycling stability, and charge–discharge performance in devices such as sodium/lithium-ion batteries, lithium-sulfur batteries, supercapacitors, and fuel cells. Recent advancements in green synthesis methods, including pyrolysis, hydrothermal carbonization, and chemical activation, are highlighted, focusing on their scalability and resource efficiency. By addressing both environmental and technological benefits, this review bridges the gap between laboratory research and practical applications. It underscores the critical role of biomass-derived graphene in achieving sustainable energy solutions and advancing the circular economy, offering a roadmap for future innovations in this rapidly evolving field.

Graphical abstract

Schematic representation of the transformation of diverse biomass resources into heteroatom-doped graphene derivatives through pyrolysis, hydrothermal carbonization, and chemical/physical activation processes. These advanced carbon materials exhibit enhanced properties for applications in electrochemical energy storage systems, including batteries, supercapacitors, and fuel cells.