Carbon Letters最新文献

Ibuprofen (IBU), a common pharmaceutical and personal care product (PPCP), is a pervasive water pollutant with adverse ecological and human health effects after transformation and accumulation. In this study, we synthesized Fe, N-doped carbon quantum dots (Fe, N-CQDs) using pig blood and FeCl₃ as a precursor via a one-step hydrothermal method. TEM, XRD, XPS, and UV–Vis were used to characterize the physical and chemical properties of Fe, N-CQDs. We investigated the feasibility of Fe, N-CQDs in activating peroxymonosulfate (PMS) for IBU degradation under visible light. The experimental results revealed that Fe in Fe, N-CQDs predominantly formed a stable complex through Fe–N and Fe-OH, with a high degree of graphitization and a sp²-hybridized graphitic phase conjugate structure. The Fe, N-CQDs/Light/PMS system exhibited strong activity, degrading over 87% of IBU, maintaining a wide pH range (3–10) adaptability. Notably, Fe, N-CQDs acted as visible-light catalysts, promoting Fe³⁺/Fe²⁺ cycling and PMS activation, generating both free radicals (SO₄^•–, ·OH) and non-radicals (¹O₂, h⁺) to effectively degrade IBU. This study presents an innovative approach for the sustainable utilization of pig blood as a biomass precursor to synthesize Fe- and N-doped carbon materials. This study provides a new approach for the sustainable and value-added utilization of natural wastes and biomass precursors of Fe- and N-doped carbon materials, which can be used to treat pollutants in water while treating discarded pig blood.

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The increasing presence of antibiotics in aquatic ecosystems has raised serious concerns about their ecological and human health impacts. In response, extensive research has focused on the degradation and removal of these stubborn pollutants. Among various approaches, heterogeneous photocatalysis has gained prominence due to its effectiveness in eliminating diverse contaminants from water. This method stands out for its cost-efficiency, environmental friendliness, and high performance, making it a practical solution for pollutant mitigation. Graphitic carbon nitride (g-C₃N₄) has attracted significant attention for developing advanced photocatalysts. Its non-metallic nature, robust stability, suitable electronic configuration, and favorable 2.7 eV band gap make it an excellent candidate. However, g-C₃N₄ faces challenges such as limited visible-light absorption, rapid charge recombination, low oxidation power, and poor texture, which hinder its photocatalytic efficiency. These issues can be addressed by developing g-C₃N₄-composite-based magnetic semiconductor photocatalysts possessing compatible energy bands. Integrating magnetic materials with g-C₃N₄ photocatalysts offers new possibilities for easy separation and recyclability, enhancing practical use. While previous studies have also detailed various modification methods for g-C₃N₄-based materials, the structure-performance relationships of g-C₃N₄, particularly for detecting and degrading antibiotics, need further exploration. This review critically examines the utilization of g-C₃N₄-based magnetic photocatalysts for antibiotic removal, exploring fabrication techniques, physical properties, and performance metrics. Various strategies to optimize their efficiency, including doping, heterojunction formation, and surface modification, are also covered. It also delves into the mechanisms of photocatalytic antibiotic degradation, addressing challenges and opportunities in developing these materials. Ultimately, we propose that the synergy of magnetic components into g-C₃N₄ not only represents a significant advancement in photocatalyst design but also opens new avenues for sustainable wastewater treatment technologies, demonstrating a high level of novelty in the field. The review provides valuable insights into current research and potential advancements in antibiotic remediation.

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The feeder pipes of the primary cooling system in a pressurized heavy water reactor (PHWR) are composed of carbon steel SA 106 GR.B. On the surface of this structural material, corrosion oxide layers including radionuclides are formed due to the presence of active species from water decomposition products caused by radiation, as well as the high temperature and high-pressure environment. These oxide layers decrease the heat transfer efficiency of the primary cooling system and pose a risk of radiation exposure to workers and the environment during maintenance and decommissioning, making effective decontamination essential. In this study, we simulated the formation of the corrosion oxide layer on the surface of carbon steel SA 106 GR.B, characterized the formed corrosion oxide layer, and investigated the dissolution characteristics of the corrosion oxide layer using oxalic acid (OA), a commercial chemical decontamination agent. The corrosion oxide layer formed has a thickness of approximately 4 µm and consists of hematite (Fe₂O₃) and magnetite (Fe₃O₄). The carbon steel coupons with formed oxide layers were dissolved in 10 mM and 20 mM OA solutions, resulting in iron ion concentrations of 220 ppm and 276 ppm in the OA respectively. In 10 mM and 20 mM OA, the corrosion depths of the coupons were 8.93 µm and 10.22 µm, with corrosion rates of 0.39 mg/cm²·h and 0.45 mg/cm²·h, respectively. Thus, this demonstrates that higher OA concentrations lead to increased dissolution and corrosion of steel.

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This study examines the effects of the TiO₂ content and TiO₂ position in the core or shell within tubular carbon nanofibers on the photocatalytic activity under visible light. Core–shell tubular carbon nanofiber composites whose cores are filled with TiO₂ nanoparticles (PMTi(10)P) are fabricated through coaxial electrospinning and subsequent heat treatment. The PMTi(10)P composites with well-preserved TiO₂ nanoparticles in the core part induce more oxygen vacancies, Ti³⁺ species, chemisorbed oxygen species, and anatase phases, significantly improving the photocatalytic performance. They act as photoelectron traps, allowing more photoelectrons and holes to participate in the photocatalytic reaction and extending the absorbance of TiO₂ to the visible light region. The resulting PMTi(10)P photocatalyst exhibits excellent performance of 100% removal of methylene blue within 30 min and maintains nearly 100% removal of 15 ppm methylene blue over 10 regeneration cycles, indicating consistent and stable photocatalytic performance.

This study explores the development and characterization of hard carbon anodes for sodium-ion batteries produced from waste coffee grounds, synthesized at both 1000 °C and 1500 °C. Importantly, this work highlights the potential of using biomass-derived hard carbons as sustainable and effective material for anode for sodium-ion batteries, contributing to the advancement of energy storage systems with increasing global demands for environmentally friendly and cost-effective technologies. The research focuses on the electrochemical performance of these hard carbons, examining how different carbonization temperatures impact their structural and electrochemical properties. Utilizing advanced analytical methods, the structural changes correlating with temperature increase were identified, including modifications in carbon atom arrangements, which significantly influence the electrochemical behaviors of the hard carbons. Our research specifically focuses on how the structural differences affect the division of capacity contribution from sloping region (above 0.1 V) and plateau regions (below 0.1 V). Electrochemical test results revealed that hard carbon with higher degree of order and reduced microstructural defects, demonstrated improved capacity values. At the same time, the highly ordered hard carbon exhibits drastic capacity loss upon increasing of current densities. The results from this study not only advance our understanding of hard carbons but also open pathways for the future exploration of hard carbons for additional improvements.

Activated carbon fibers (ACFs) have emerged as promising adsorbents for environmental applications in the removal, separation, and modification of organic compounds in liquid and gas phases. Recent research has focused on enhancing the effectiveness of ACFs via precursor and surface modification, aiming to enhance their affinity for specific pollutants. Hence, the present review reports recent research advances in this area, focusing on ACF production and modification techniques, along with their respective advantages and disadvantages. After a brief description of ACFs, their state-of-the-art surface modification techniques are systematically summarized, divided into two categories: (i) type of precursor [e.g., polyacrylonitrile (PAN), pitch, phenolic resin (e.g., novoloid), biomass] and (ii) type of surface modification (wet or dry). In short, this review presents recent advances in the preparation and modification of ACFs for the removal of organic compounds from aqueous and gas phases; various fabrication techniques and the adsorption mechanisms of organic compounds are also discussed in detail.

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The surface treatment processes of carbon fibers is very important, because of their significant impact on fiber handling, filament protection, and interfacial properties. In this study, the effects of two different sizing agents with different molecular weights, with or without a nonionic surfactant, on the performance of a melt-spun polyacrylonitrile-based carbon fiber and carbon fiber/epoxy interfacial adhesion are investigated. The focusing property and spread-ability of a low-molecular-weight sizing agent with a surfactant show outstanding performances because of the high penetration between the fibers and high interfacial bonding with the fibers. In addition, wettability of the matrix (epoxy resin) of the low-molecular-weight sizing agent are superior to those of the high-molecular-weight sizing agent. Furthermore, the nonionic surfactant used as an assistant improves the sizing amount and wettability by forming micelles with the epoxy. The interfacial shear strength (IFSS) of the low-molecular-weight sizing agent with a surfactant is also superior to that of other sizing agents. The IFSS is closely related to the sizing amount of the coating on the carbon fiber surface and matrix wettability.

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A substantial quantity of discarded tires has inflicted harm on the environment. Microwave pyrolysis of discarded tires emerges as an efficient and environmentally friendly method for their recycling. This research innovatively utilizes the characteristics of microwave rapid and selective heating to pyrolyze waste tires into porous graphene under the catalysis of KOH etching. Moreover, this study comprehensively investigates the dielectric characteristics and heating behavior of waste tires and different proportions of waste tire–KOH mixtures. It validates the preparation of graphene through KOH-catalyzed microwave pyrolysis of waste tires, tracking morphological and structural changes under varying temperature conditions. The results indicate that optimal dielectric performance of the material is achieved at an apparent density of 0.68 g/cm³ at room temperature. As the temperature increases, the dielectric constant gradually rises, particularly reaching a notable increase around 700 °C, and then stabilizes around 750 °C. Additionally, the study investigates the penetration depth and reflection loss of mixtures with different proportions, revealing the waste tire–KOH mass ratio of 1:2 demonstrates favorable dielectric properties. This research highlights the impressive microwave responsiveness of the waste tire–KOH mixture, Upon the addition of KOH, the mixed material exhibits an augmented dielectric constant and relative dielectric constant, supporting the viability of KOH-catalyzed microwave pyrolysis for producing porous graphene from waste tires. This method is expected to provide a new method for the valuable reuse of waste tires and a technology for large-scale, efficient and environmentally friendly production of graphene.

In response to the urgent need for sustainable and environmentally friendly materials, this study focuses on enhancing the flame retardancy and mechanical properties of epoxy composites using eco-friendly, non-halogen flame-retardant hybrid fillers. These fillers are synthesized from tannic acid (TA) and upcycled carbon black derived from waste tires (WT-CB) via a mechano-fusion process. The resulting TA/WT-CB fillers exhibit a core–shell structure, with WT-CB uniformly coating the TA surface, significantly improving flame retardancy compared to TA alone. When incorporated into epoxy resin, the TA/WT-CB fillers not only enhance flame resistance but also improve the composite’s mechanical properties. Optimal performance was observed at a filler content of 5 wt.%, where the composite demonstrated superior flame retardancy and mechanical strength. This innovative approach not only addresses fire safety concerns but also promotes sustainability by utilizing upcycled waste materials, offering a promising solution for environmentally conscious flame-retardant technologies.

Considering the intrinsic activity of non-precious metal oxygen reduction reaction (ORR) catalysts is typically lower than that of precious metal catalysts, it is crucial to focus on the rational design of their micro-morphology and active site. This paper employed a simple molten salt-mediated template method to fabricate a Fe₃C composite N-doped C catalyst with a layered porous framework (Fe₃C@NC). Tannic acid was utilized to form a strong coordination with iron to limit the grain size of Fe₃C nanocrystals generated by high-temperature pyrolysis. Moreover, urea achieved nitrogen doping in tannic acid-derived porous carbon, while the graphite phase nitrogen-doped carbon (g-C₃N₄) formed by its pyrolysis, together with the molten salt-mediated environment, jointly controlled the two-dimensional sheet-like structure of the material. The optimized Fe₃C@NC-800 demonstrated efficient ORR performance, with an ORR half-wave potential of 0.883 V. Its application as a cathode catalyst in a liquid zinc-air battery (ZABs) exhibits a maximum power density of 211.5 mW cm⁻², surpassing that of a Pt/C-based ZAB and indicating the potential practical utility of this material.