Carbon Letters最新文献

This study explores the electrochemical modification of reduced graphene oxide (rGO) by incorporating 1,10-phenanthroline groups prior to the electrodeposition of silver nanoparticles (Ag NPs), aiming to enhance the performance on the oxygen reduction reaction (ORR). The introduction of 1,10-phenanthroline onto the rGO surface significantly improved its ability to coordinate metallic cations, compared to unmodified rGO. This enhanced coordination capacity led to a more efficient deposition of Ag NPs. Notably, increasing the amount of 1,10-phenanthroline groups grafted onto the rGO further boosted the number of deposited Ag NPs, substantially improving ORR performance. These results demonstrate that increasing the number of coordination units on rGO sheets prior to metal incorporation can significantly enhance the electrocatalytic efficiency of the resulting nanocomposites. This work emphasizes the importance of functionalizing rGO surfaces to optimize their catalytic properties for energy conversion and storage applications. This modification of rGO also paves the way for broader potential applications across various fields.

Microorganisms perform a crucial function in the biogeochemical processes that maintain soil quality. Nonetheless, the influence of biochar on soil microbial communities and their ecological functions remains poorly understood in black soils. To investigate this, a 2-year field experiment was conducted with four biochar application treatments: 0 t ha⁻¹ (CK), 6 t ha⁻¹ (BC6), 12 t ha⁻¹ (BC12), and 24 t ha⁻¹ (BC24). Microbial diversity and community composition under each treatment were assessed using high-throughput sequencing techniques. PICRUSt2 and FUNGuild were employed to predict microbial functional profiles. Compared to the control (CK), biochar addition led to notable shifts in both bacterial and fungal community structures. It also significantly enhanced bacterial α-diversity, as reflected by increased Shannon index, OTU counts, and Chao1 richness. However, a gradual decline in bacterial diversity was observed with rising biochar application rates. Taxonomic analysis revealed that biochar treatment significantly elevated the relative abundances of specific bacterial groups—such as Acidobacteria, Chloroflexi, Candidatus_Solibacter, and Bryobacter—as well as fungal groups such as Ascomycota, Zygomycota, Mortierella, Penicillium, and Fusarium. These effects were most evident under the moderate application rate (BC6). These microbial community changes may contribute to maintaining agroecological functions and soil health in biochar-amended soils. Regarding ecological functions, biochar application enhanced soil bacterial metabolic potential and saprotrophic fungal abundance, with more significant effects in the BC6 treatment, while reducing plant pathogenic fungi. This suggests beneficial effects on soil health maintenance and elemental cycling. Therefore, from the perspective of soil microbial community characteristics, biochar application positively influences black soil quality improvement. Considering environmental and economic benefits, a lower biochar application rate (6 t ha^⁻1) may represent an optimal strategy for carbon sequestration, soil quality enhancement, and agroecological function maintenance in the studied system.

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The slow cathodic oxygen reduction rate (ORR) of microbial fuel cells (MFCs) is still one of the main bottlenecks in its industrialization. As an ORR catalyst, metal oxides are expected to significantly enhance ORR efficiency by providing active sites, regulating reaction pathways, and enhancing stability. In this paper, four bimetallic oxide catalysts, CuO/Co₃O₄, CuO/MnO₂, CuO/NiO, and CuO/Fe₂O₃, were synthesized by sol–gel method, and their structural characteristics were characterized. The results showed that CuO/Co₃O₄ exhibited the largest specific surface area and optimized pore structure, and the synergistic effect of Cu and Co significantly improved the electrochemical performance. As the cathode catalyst of MFCs, CuO/Co₃O₄ shows high ORR catalytic activity, low charge transfer resistance, and good stability. In MFCs application, CuO/Co₃O₄ catalyst achieved the maximum power density of 227 mW m⁻². In the five-cycle test, the output voltage is stable at about 240 mV, and the COD removal rate reaches 91.9%, which shows great application potential in wastewater treatment.

In this study, GNPs/FeCoNiCuAl particles synergistically reinforced aluminum matrix composites are developed by friction stir processing (FSP) to explore the effects of different GNPs contents (1, 3, and 5%) on the microstructure, mechanical performance, and wear resistance of the materials. The results show that the incorporation of GNPs affects the formation of the diffusion layer between the FeCoNiCuAl particles and the aluminum matrix. As the content of GNPs increases, the thickness and integrity of the diffusion layer between FeCoNiCuAl particles and aluminum matrix gradually decrease. In addition, the introduction of GNPs is beneficial in enhancing the proportion of high-angle grain boundaries in the composites, but the grain size of the specimen increases slightly to about 5.5 μm at a content of 5% GNPs. When the content of GNPs is 1%, the composites achieve the highest microhardness and the lowest specific wear rate (0.1459 × 10⁻⁶ mm³/N·m), with the wear mechanism dominated by abrasive wear. Nonetheless, when the GNPs content in the composite increases to 5%, the thickness and integrity of the diffusion layer are minimal, causing the tensile strength of the composite to be reduced to 250 MPa, and the specific wear rate increased to 0.4244 × 10^–6 (mm³/N·m), with the wear mechanism transformed to abrasive–adhesive mixed wear. This study demonstrates that the appropriate ratio of GNPs and FeCoNiCuAl particles can effectively enhance the mechanical and wear resistance properties of aluminum matrix composites, providing a theoretical basis for the design and development of high-performance aluminum matrix composites.

Recent advancements in 2D graphene materials highlight their versatile applications in electronics, clean energy, medicine, and other fields due to their exceptional properties and ease of fabrication. The current study investigates the preparation of reduced graphene oxide (RGO) through the thermal exfoliation of graphite oxide under an air atmosphere at varying temperatures (200–500 °C) and further examines its suitability as an anode for lithium-ion (Li-ion) batteries. The extent of reduction of functional groups, exfoliation, and other physical changes is analyzed by XRD, SEM, XPS, BET, and Raman studies, which show that the reduction of functional groups and surface area increases with increasing exfoliation temperature. The RGO electrodes are subjected to electrochemical studies, including cyclic voltammetry and charge–discharge cycling at various current densities, which demonstrate varying discharge capacities for RGO samples prepared at different temperatures. The RGO exfoliated at 400 °C delivered the maximum capacity, indicating that this temperature is optimal for the thermal preparation of RGO. This material shows potential for use as an anode in Li-ion batteries.

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Bimetallic sulfides, as high-performance anode materials, exhibit high theoretical capacity. However, their practical application is hindered by inherent limitations, such as low electrical conductivity, sluggish charge transfer kinetics, and severe volume expansion. Interface-engineered heterostructures have emerged as a universal strategy to synergistically enhance conductive networks and suppress mechanical degradation. Carbon-based composites serve as optimal substrates due to their high conductivity and structural flexibility. In this study, we leverage the hierarchical porous architecture of expanded graphite (EG) to confine the self-assembly of Zn/Co precursors via a thiourea-assisted hydrothermal method, enabling in situ growth of Zn_0.76Co_0.24S nanoparticles within EG interlayers. Interfacial S–C covalent bonding, induced by π–π conjugation, establishes robust nanoscale coupling between Zn_0.76Co_0.24S and the carbon framework. The resulting “sandwich” heterostructure demonstrates exceptional cyclability (1086.9 mAh·g⁻¹ after 500 cycles at 1.0 A·g⁻¹) and rate capability (541.7 mAh·g⁻¹ at 2.0 A·g⁻¹). This work provides a generalizable design paradigm for high-performance multimetallic sulfide anodes through atomic-scale interface engineering.

Graphite crystals consist of a layered structure with stacked graphene sheets, and exhibit self-lubricating properties due to the facile sliding of graphene layers in the horizontal direction, facilitated by weak Van der Waals bonds along the c-axis. When this graphite material is impregnated with a lubricating liquid, it forms a solid and stable lubricating layer, and effectively reduces damage to the counter material from friction-induced wear under conditions of high-load reciprocating motion. This study investigates how oxidation-induced pore expansion and the silane treatment of graphite affect lubricating oil impregnation behavior, the friction coefficient of impregnated graphite, frictional stability, and microstructural changes at the friction surface. It was found that graphite oxidation within the chemical reaction temperature range enhanced porosity and increased the rate of lubricating oil impregnation. The functionalization of the graphite surface with hydrophobic silane coupling agents also significantly enhanced oil uptake, with a pronounced observed improvement when utilizing hydrophobic oils. Under a vertical load of 360 kgf and a surface pressure of 3 MPa, the graphite surface treated with hydrophobic silane and impregnated with oil exhibited the lowest average friction coefficient of 0.192 over 600 cycles. During the friction and wear process, a lubricating layer formed on the graphite surface, which contributes to stable wear performance. This surface modification strategy offers high applicability in industries such as automotive, aerospace, and heavy machinery, with the potential to significantly enhance component performance and extend service life under high-load, low-speed reciprocating conditions.

Poor bonding occurs with resin due to surface inertness of carbon fiber (CF), so CF surfaces were often treated. In some common surface treatments, sizing was a simple and effective modification method. Polyurethane (PU) was used as the main component of sizing agents due to its similar structure to polyamide 6 (PA6). The CF/PA6 composites’ interfacial properties were improved using PU as a sizing agent. Meanwhile, in this paper, glycidol (GLD) was introduced into the PU emulsion so that the epoxy group reacted with the carboxyl group on the acidified CF. After testing, when the content of glycidyl in the sizing agent is 2%, the CF/PA6 composites showed an important improvement in tensile, impact, and flexural strengths, which increased by 49.4%, 94.6%, and 53.2%, respectively. In addition, the effect of modified WPU sizing agents with different GLD contents on the properties of CF/PA6 composites was investigated.

In this study, a composite material based on agricultural waste coconut shells was successfully developed as an efficient, lightweight, and sustainable electromagnetic wave (EMW) absorber. Specifically, coconut shells were used as the raw material, and a simple one-step activation charring process was employed to obtain coconut shell porous carbon (CSPC). ZnFe₂O₄ with a hollow spherical structure was then in situ grown on the surface of CSPC, resulting in a special ZnFe₂O₄/CSPC composite material. Due to its unique hollow structure, porous characteristics, and heterogeneous interfaces, the composite material achieved optimized impedance matching, leading to excellent EMW absorption performance. The fabricated ZnFe₂O₄/CSPC composite demonstrated a minimum reflection loss (RL_min) of − 37.32 dB at 10.80 GHz and an effective absorption bandwidth of 2.40 GHz at a thickness of only 2.0 mm. SEM and TEM analyses confirmed that the composite possessed a hollow and porous structure, while the BET specific surface area was measured at 133.709 m² g⁻¹. Based on the synergistic effects of ZnFe₂O₄ and CSPC, dielectric losses, magnetic losses, and impedance matching, the potential EMW absorption mechanisms were proposed. The ZnFe₂O₄/CSPC composite material prepared in this study was a novel, green, and sustainable EMW absorber.

The integration of high-capacity active materials onto flexible substrates is essential for advancing flexible sodium-ion batteries (SIBs). Herein, we report a novel strategy for fabricating high-performance, flexible SIB anodes via the immobilization of molybdenum disulfide (MoS₂) nanoparticles on carbon cloth (CC) modified with metal–organic framework-derived carbon nanotubes (MOF-derived CNTs). In this method, Co-containing zeolitic imidazolate frameworks (ZIFs) were assembled on polyaniline-coated CC, followed by CNT growth via chemical vapor deposition (CVD) and hydrothermal deposition of MoS₂. The resulting MoS₂@CNT@CC electrodes achieved significantly higher MoS₂ loading (15–20 wt%) compared to direct deposition on CC (< 5 wt%). Electrochemical evaluation revealed an initial discharge capacity of 231 mAh g⁻¹ with a Coulombic efficiency of 94.3%, outperforming MoS₂@CC (150 mAh g⁻¹, 77.8%) and bare CC (113 mAh g⁻¹, 74.3%). After 100 cycles at 50 mA g⁻¹, MoS₂@CNT@CC maintained a stable capacity of 133 mAh g⁻¹ and an average Coulombic efficiency of 99.9%. Cyclic voltammetry confirmed enhanced redox activity, while mechanical tests showed no significant degradation after 10,000 bending cycles (10 mm radius). These findings highlight the effectiveness of MOF-derived CNTs in enhancing MoS₂ loading, conductivity, and mechanical resilience, offering a promising route toward robust and efficient flexible SIB anodes.