Carbon Composite Materials Research Articles

Preparation of natural N/O/S co-doped biomass-derived carbon materials for supercapacitors using multistage gas self-exfoliation effect

High-value utilization of biomass provided a feasible way to solve the energy shortage and environmental problems. The preparation of micro-mesoporous composite carbon materials from biomass waste as feedstock using a multistage gas self-exfoliation mechanism (CH3COOK and Ca2(C2H5COO)2) was a feasible approach. Among them, the N, O and S co-doped carbon materials were obtained in this paper by using forestry waste (bamboo) as raw material, spiral algae as green heteroatom dopant, Ca2(C2H5COO)2 as multifunctional template agent, and CH3COOK as gentle activator. The results indicated that BC-SA-0.5CP exhibited 324.85 F/g at 0.5 A/g. The symmetric supercapacitor (BSC-0.5//BSC-0.5) achieved 96.02% capacitance retention after 10,000 cycles, indicating excellent rate performance and charge/discharge stability. At a power density of 162.5 W/kg, the BSC-0.5//BSC-0.5 had an energy density of 14.67 Wh/kg. In addition, it was deeply analyzed the growth mechanism of heteroatoms, the formation mechanism of porous carbon and the electron transfer routes, which provided a theoretical basis for the preparation of biomass-derived carbon materials. Overall, this study demonstrated that the multistage gas self-exfoliation mechanism was beneficial in promoting the formation of micro-mesoporous composite structures and the growth of heteroatom functional groups, which ultimately provided a new route for the synthesis of natural heteroatom-doped porous carbon.

Synthesis of natural oxygen-doped bamboo-derived hierarchical micro-mesoporous composite carbon materials using a green activation strategy

Utilizing biomass waste to synthesize hierarchical micro-mesoporous composite carbon materials for application in the field of supercapacitors realized green and sustainable energy development. This paper efficiently synthesized natural O-doped carbon materials using bamboo as biomass material by simple air pre-oxidation and secondary carbonization methods. Among them, KCl acted as a recyclable templating agent and flame retardant, facilitating the construction of mesoporous structures. The green activator CH3COOK promoted the generation of micropores. The combination of dual activation strategies (physical and chemical) contributed to the conversion of bamboo to hierarchical micro-mesoporous composite carbon materials. During pre-carbonization, air was used as a natural dopant which etched the carbon material and promoted the creation of oxygenated functional groups. The best carbon material exhibited an excellent electrochemical capacity of 321.65 F/g in 6 M KOH electrolyte. Furthermore, the symmetric supercapacitor exhibited high cycling stability (95.52 %) and outstanding power density. This work provided a new idea for preparing controllable biomass-derived carbon materials, while offering a reference for applying dual activation strategies in carbon material synthesis.

CHAMBER FURNACE FOR SIMULATION OF CARBON MATERIALS HEAT TREATMENT IN ELECTROTHERMAL FLUIDIZED BED

Existing laboratory furnaces for high-temperature heat treatment of materials at around 3000°C, which have graphite heaters, allow samples to be heated at a rate two orders of magnitude lower than in electrothermal fluidized bed furnaces. This makes it impossible to use them in the research into the heat treatment of carbon materials because they do not meet the conditions of shock heating and do not allow to keep accurate residence time. The paper presents the research into the use of low-density composite carbon materials as heaters. Based on the results obtained, a high-temperature chamber furnace was designed, studied, and the temperature field in the heater was simulated. As a result, a high-temperature laboratory furnace was created with a sample heating rate of 20 °C/s - 100 °C/s, which made it possible to use it to simulate the heating process in the electrothermal fluidized bed furnace. Comparison of energy consumption in the furnace with a traditional graphite heater and a low-density carbon composite heater showed that heat loss in the furnace is reduced by 1.7 to 1.8 times.

Enhancing the supercapacitive performance of a carbon-based electrode through a balanced strategy for porous structure, graphitization degree and N,B co-doping

Regarding carbon-based electrodes, simultaneously establishing a well-defined meso-porous architecture, introducing abundant hetero-atoms and improving the graphitization degree can effectively enhance their capacitive performance. However, it remains a significant challenge to achieve a good balance between defects and graphitization degree. In this study, the porous structure and composition of carbon materials are co-optimised through a ‘dual-function’ strategy. Briefly, K3Fe(C2O4)3 and H3BO3 were hybridised with a gelatin aqueous solution to form a homogeneous composite hydrogel, followed by lyophilisation and carbonisation. Owing to the dual functionality of raw materials, the graphitization, activation and hetero-atom doping processes can occur simultaneously during a one-step high-temperature treatment. The resultant carbon material exhibits a high graphitization degree (ID/IG = 0.9 ± 0.1), high hetero-atom content (N: 9.0 ± 0.3 at.%, B: 6.9 ± 0.5 at.%) and a large specific area (1754 ± 58 m2/g). The as-prepared electrode demonstrates a superior capacitance of 383 ± 1F g−1 at 1 A/g. Interestingly, the cyclic voltammetry (CV) curves exhibit a distinctive pair of broad redox peaks, which is uncommon in KOH electrolyte. Experiment data and density functional theory (DFT) simulation verify that N-5, B co-doping enhances the activity of the faradic reaction of carbon electrodes in KOH electrolyte. Furthermore, the fabricated Zn-ion hybrid supercapacitor (ZHSC) based on this carbon electrode delivers a high-energy density of 140.7 W h kg−1 at a power density of 840 W kg−1.

Redox transformation of bismuth active units encapsulated on carbon nanorods for efficient fluoride Electrosorption: Synergistic roles of Faradaic effect and EDL capacitance

Remediation of fluoride in groundwater through electrosorption to cope with its high charge density and the smallest anion radius remains a promising strategy. Composite carbon materials obtained by calcining metal–organic frameworks contribute to the performance of conventional fluoride electrosorption systems. This study provides a redox-active electrode (MBiC@tE) that incorporates the Faradaic ion trapping effect for fluoride removal. Under potential control, MBiC@tE reversibly traps/releases fluoride anions from the aqueous solution through the combined roles of Faradaic pseudocapacitance and electrical double layer capacitance, with an electrosorption capacity of approximately 37.9 mgF- gelectrode-1. The target contaminant anions are directly involved in the Faradaic reaction on the bismuth sites, with the formation of Bi-F bond excited by an electric field, thus resulting in the removal of fluoride as a consequence of the generation of insoluble substance (BiF3). Furthermore, as expected (Bi0 + 3F- ⇌ BiF3 + 3e-), the working electrode exhibits good reversibility and maintains a high fluoride removal capacity even after multiple cycles. This study presents a comprehensive elucidation on the synergistic roles of Faradaic effect and electrical double layer capacitance induced by the electric field, and offers profound insights into the phase transition of bismuth and its affinity for fluoride during the electrosorption.

Investigation of the Durability and Performance of Gears Made of Glass Fiber, Carbon and Bronze-Reinforced Polytetrafluoroethylene Matrix Composite Material

Polymer gears are often used in power transmission due to their numerous advantages. Heat accumulates on polymer gears during operation. Over time, this accumulated heat leads to damage; and shortens the service life of the gears. To prevent this, various fillers are added to the polymer materials. These fillers help to dissipate the heat generated on the gears. In this study, 25% glass fibers, 35% carbon powder, and 60% bronze particles were added to the polytetrafluoroethylene (PTFE) matrix to determine the wear behavior of gears. The properties of the matrix and the filler mainly influence the wear behavior of PTFE composites. The study showed that all composite gears with filler have better wear resistance than pure PTFE gears due to their better thermal stability. After the tests, it was found that the gears made of PTFE + 35% carbon additive had about 12 times better wear rates than those made of pure PTFE. Based on the average temperature values of the experiment, it was found that the mass temperature of gears made of 35% carbon-doped PTFE is about 38-39% lower than that of pure PTFE. This study contributes to the standard studies on heat build-up, thermal damage, and wear of gears made of polymers with different fillers and ratios.

Zirconium-based metal–organic frameworks/porous carbon hybrids as high-performance anode materials for highly stable lithium- and potassium-ion batteries

Metal-organic framework (MOF)-derived carbon materials have been widely investigated as advanced electrode materials. However, post-synthetic modifications suffer from certain limitations in morphology, surface area, and pore size control. Herein, we report a simple strategy to synthesize surface-confined Zirconium(Zr)-based MOF UiO-66-NH2 carbon hybrids (Zr-MOF@C; denoted as Zr-MOF, Zr-MOF@C10, Zr-MOF@C25, and Zr-MOF@C50) through a covalent assembly/amide linkage between the MOFs and hierarchical porous carbon (PC) in various proportions under solvothermal conditions. Zr-MOF@C hybrids have been utilized as the anode materials for lithium- (LIBs) and potassium-ion batteries (KIBs). In LIBs, the Zr-MOF@C10, Zr-MOF@C25 and Zr-MOF@C50 anodes delivered the discharge capacities of 126, 65 and 94 mA h g−1 at 100 mA g−1 after 100 cycles, respectively. In KIBs, the Zr-MOF@C10 and Zr-MOF@C25 exhibited the high discharge capacities of 78 and 70 mA h g−1 at 100 mA g−1 over 100 cycles. In addition, the Zr-MOF@C25 and Zr-MOF@C50 anodes exhibited an outstanding rate capability with a reversible capacity of ∼166 mA h g–1 vs. K/K+ and 176 mA h g–1 for Li/Li+, respectively, while well-maintained long-term cyclic stabilities of ∼57 mA h g–1 (Zr-MOF@C25 vs. K/K+) and ∼140 mA h g–1 (Zr-MOF@C50 vs. Li/Li+) at 1 A g–1 over 1000 cycles. The electrochemical kinetics studies revealed that Li+ and K+ storage efficiencies of all anodes were dominated by a surface-charge capacitive effect and diffusion-driven charge storage mechanism, respectively. These findings provide new insights for designing high-performance surface-confined MOF-based carbon composite materials for next-generation high-energy storage devices.

Innovative design of silicon-core mesoporous carbon composite for high performance anode material in advanced lithium-ion batteries

Silicon is widely recognized as an exceptionally auspicious anode material for lithium−ion batteries due to its remarkable specific capacity, suitable operational potential, and ecologically innocuous characteristics. This study presents a novel silicon@void@FC (fibrous carbon) composite anode material for lithium-ion batteries. Utilizing a one-step synthesis approach, the resulting hollow core–shell structure, combined with a mesoporous carbon shell, demonstrates exceptional electrochemical performance. The Si@Void@FC electrode exhibits remarkable cycle stability and rate performance, maintaining structural integrity over 500 cycles without observable degradation. The outer carbon shell acts as a protective layer and accommodates silicon volume expansion during cycling, preventing excessive contact with the electrolyte. The rich mesoporous structure facilitates efficient lithium-ion diffusion, enhancing lithiation and delithiation processes. The simplified one-step synthesis method further streamlines the preparation process, eliminating the need for complete silica template formation. This innovative Si@Void@FC composite material holds promise for advancing lithium-ion battery technology, addressing challenges associated with silicon-based anode materials, and offering insights into the design and synthesis of high-performance energy storage materials.

Ferrite doped sucrose-derived porous carbon composites inspired by Pharaoh's Serpent for broadband electromagnetic wave absorption

This paper presents a straightforward and intriguing approach for designing wide bandwidth, lightweight, and tunable electromagnetic wave (EMW) absorbing materials. Drawing inspiration from the "Pharaoh's Snake", biomass carbon source and sucrose were used to fabricate Fe/Fe3O4@porous carbon (PC) composite materials through combustion experiments. Subsequently, high-temperature calcination was applied to enhance the microwave absorbing properties of the materials. The as-prepared composites demonstrate an impressive 6.62 GHz effective bandwidth and an excellent absorption ability of −51.54 dB at a matched thickness of 2.2 mm. Moreover, by tuning the content of magnetic particles and controlling the thickness of the composite material, comprehensive coverage across C, X, and Ku bands can be achieved. The outstanding performance suggests that the synthesized Fe/Fe3O4@PC porous materials hold significant potential for applications in electromagnetic wave absorption. It opens up a novel, straightforward, and cost-effective approach to acquiring broadband absorbing materials.

Determining the Most Efficient Method of Strengthening the Reinforced Concrete Columns under Different Loading Levels

Introduction. The method of strengthening the reinforced concrete structures is chosen depending mainly on the cost and timeframe of the performed work. In each specific case, the decision is made depending on the load, type of defects, operational features, etc. Apart from the direct costs of inspection, strengthening project design, materials, lifting and transport services and the cost of strengthening works proper, there is a number of additional costs related to the technological features of the work performed. Among the new methods of strengthening, the method of external strengthening with the composite carbon materials can be particularly emphasised. Compared to the previously developed methods of strengthening with the reinforced concrete and metal, the composite systems are easily transportable and do not incur additional costs. The aim of this study is to determine the method of strengthening most rational for the compressed structures.Materials and methods. The authors have examined three methods of strengthening the compressed reinforced concrete structures. In the frame of the research a numerical experiment has been carried out, in which a reinforced concrete column was strengthened at different strengthening coefficients from 1.1 to 2.0, i.e., from 10 to 100% of strength increase. The estimations of the cost of strengthening the column by three methods of strengthening have been carried out: jacketing using the reinforced concrete, metal and composite materials. After carrying out thirty variants of calculation, a table presenting all specifications and quantities of the materials has been drawn up. At the final stage of the research, the total cost of each method under investigation has been estimated based on the prices of the selling companies.Results. The analysis of strengthening with the reinforced concrete revealed that at most of the strengthening coefficients the achieved structural reinforcement is minimal. Under the high loading levels strengthening with the metal is not economically expedient, as it implies the use of the large-section angles. The composite material systems of external strengthening are very material-consuming at all load increasing coefficients. Taking into account the high cost of materials, this method is basically the least economically expedient.Discussion and conclusion. Based on the results obtained, the efficiency of three most common methods of strengthening the reinforced concrete compressed columns was analysed. Proposals on the rational design of the strengthening systems for the eccentrically compressed reinforced concrete poles under the different eccentricities of load applied have been developed.

Aging of Adhesives of External Reinforcement Systems of Building Structures. Part 1. Investigation of the Significance of Influencing Factors

External reinforcement systems using carbon composite materials are one of the modern methods of strengthening building structures. As the results of existing scientific research show, the component most susceptible to external factors in these systems is an epoxy adhesive. In the present work, experimental studies have been carried out in order to obtain data for the development of a standard method for accelerated assessment of the durability of building structures reinforced with external reinforcement systems with polymer composites. The importance of influencing factors such as: UV radiation; temperature; moisture and alkaline solution on the aging rate of adhesives for external reinforcement systems has been revealed. A step stress method is proposed to predict the creep of the initial and aged adhesive samples.

A magnetic metal composite biomass carbon material with high efficiency and broadband wave absorbing property

A magnetic metal composite biomass carbon material with high efficiency and broadband wave absorbing property

A cellulose derived nanofibrous nitrogen-doped carbon/TiO2/SnO2/carbon composite anodic material for lithium storage

SnO2 with high theoretical specific capacity is regarded as a desirable anodic material for lithium storage. However, the serious volume variation during discharge/charge cycling and poor conductivity significantly constrain the electrochemical performance. Herein, nanofibrous nitrogen-doped carbon (NC)/TiO2/SnO2/carbon composite was fabricated through layer-by-layer assembly of SnO2 and TiO2-gel layers alternately using cellulosic filter paper as the structural scaffold, followed by deposition of polypyrrole on the surface by chemical polymerization method, and subsequent calcination of the as-obtained matter in inert atmosphere. The achieved composite possesses a typical three-dimensional fibrous porous network structure inherited from the cellulosic substrate, and complete NC nanolayer coating on each nanofiber by adjusting the amount of pyrrole, which can alleviate the volume change and increase the conductivity of SnO2. Furthermore, the interlaced TiO2 multilayer can enhance the cycling stability during cycling, as well as facilitate the lithium-ion transfer through abundant interface. The optimal NC/TiO2/SnO2/carbon composite delivers an initial discharge capacity of 1492.6 mAh g−1 at a current density of 100 mA g−1, and retains a reversible capacity of 680.8 mAh g−1 after 200 discharge/charge cycles. This work provides an efficient strategy for design and construction of metal-oxides/carbon composite anodic materials with hierarchical microstructure that hold great potential in lithium storage.

Inductively coupled plasma spectroscopy for heteroatom-doped carbonaceous materials: Limitations and acid choice for digestion

Heteroatom-doped carbonaceous materials have garnered significant attention in the fields of catalysis, energy conversion and storage, and pollutant recovery. However, accurately determining the doping extent remains a delicate task in a number of cases (e.g. phosphorus, boron, selenium), often leading to conflicting data from different characterization techniques. Inductively Coupled Plasma (ICP) spectroscopy stands out as a routine technique; nevertheless, reliable results necessitate appropriate digestion protocols. In this study, we demonstrate on a series of P-doped samples, with P contents ranging from 2 to 14 wt%, how the choice of acids (HCl, HNO3, H2SO4) and oxidizing compounds (H2O2) for digestion drastically affects the results, with variations of up to 620 %. Though commonly used, aqua regia proved highly unreliable, particularly for P-doped carbon nitrides, while piranha solution appeared as a promising alternative, with a precision, i.e. a coefficient of variation, ca. 5.0 %. The contents deriving from piranha solution digestion were subsequently comforted through X-ray Photoelectron Spectroscopy. We finally put in perspective the use of ICP in terms of sensitivity and accuracy with the main analytical techniques employed in literature to determine the element composition of carbon materials.

Continuous Supercritical Water Impregnation Method for the Preparation of Metal Oxide on Activated Carbon Composite Materials

Metal oxide (MexOy) nanomaterials are used as catalysts and/or sorbents in processes taking place in supercritical water (scH2O), which is the “green” solvent needed to obtain energy-relevant products. Their properties are significantly influenced by the synthesis method used to prepare active MexOy. In addition, the use of supported MexOy nanoparticles is more practical and cost-effective in terms of their performance maintenance. Within this context, the present study reports on the preparation of carbon-supported ZnO and CuO composites using an innovative scH2O impregnation method. Metal oxides were impregnated on a carbon (C) support using a continuous-flow tubular reactor. The results show that impregnation in scH2O is a promising approach for the preparation of ZnO/C and CuO/C composite materials. This one-step synthesis method, in a continuous flow, uses neither a seed layer nor a mineralizer, and it needs substantially lower preparation times than conventional impregnation methods.

Shape-stabilized nanosilver-modified grapefruit peel-based porous carbon composite phase change material with high thermal conductivity, photothermal conversion performance and thermal management capability

Polyethylene glycol (PEG) is greatly limited in the fields of phase change heat storing and solar energy absorption due to its low thermal conductivity, poor thermal stability and weak photo-thermal effect. Aiming at solving the above concerns, this work structures a new composite phase change material (PCM)(PEG/BPC@Ag) with biomass grapefruit peel-based porous carbon foam (BPC) as the backbone material and Nano-Ag as a surface-modified component, and the phase change medium PEG by simple vacuum immersion method. The test findings revealed that the modified carbon foam with Nano-Ag has excellent three-dimensional structure and photo-thermal effect, which makes the prepared composite PCM(CPCM) have enhanced photo-thermal transformation capacity, an enhanced thermal conductivity and excellent thermal stability. Among them, the thermic conductivity of the PEG/BPC@Ag was increased by 2.1 folds to 0.68 W/Mk. similarly, its enthalpy efficiency λ and was increased from 82.0 % to 83.7 %, and the photo-thermal transformation performance θ was increased from 76.8 % to 91.2 %. As well, the PEG/BPC@Ag has exceptional reusability and thermic robustness performance. Comprehensively, the PEG/BPC@Ag prepared in this work has a wide potential for application both in waste heat recovery and solar energy absorption, as well as in thermal management of electronic components, as well as providing a feasible solution for solid waste recycling in utilization.

A clinical example of using a carbon-carbon composite to replace a femur diaphyseal defect

A separate direction in osteosynthesis is the study on the possibilities of bone union after tumor resection. In this regard, the issue of using implants made of metals, polymers, and carbon, which have a high bone binding affinity, is on the agenda for modern oncological orthopedics. Studying carbon composite materials has shown practical effectiveness of their medical use, in particular in orthopedics and traumatology, that can be applied to replace bone defects in oncological traumatology. Aim. To determine the possibility of using carbon composite materials in the femur defect replacement after tumor resection. Clinical case. A case of using an implant made of the carbon composite material for a patient with right femur osteosarcoma and a pathological femoral middle-third fracture is presented. The study was carried out in accordance with the principles of the Declaration of Helsinki. The patient signed the written informed consent form for the study. Conclusions. The results of using the implant made of the carbon composite material have shown its permeability to X-rays and potential use for bone defect replacement in oncological traumatology.

Oxalic acid-assisted preparation of LTO-carbon composite anode material for lithium-ion batteries

This study presents an oxalic acid-assisted method for synthesizing spinel-structured lithium titanate (Li4Ti5O12; LTO)/carbon composite materials. The Ag-doped LTO nanoparticles (NPs) are synthesized via flame spray pyrolysis (FSP). The synthesized material is used as a precursor for synthesizing the LTO-NP/C composite material with chitosan as a carbon source and oxalic acid as an additive. Oxalic acid improves the dissolution of chitosan in water as well as changes the composition and physical and chemical properties of the synthesized LTO-NP/C composite material. The oxalic acid/chitosan ratio can be optimized to improve the electrochemical performance of the LTO-NP/C composite material, and the electrode synthesized with a high mass loading ratio (5.44 mg cm−2) exhibits specific discharge capacities of 156.5 and 136 mAh g−1 at 0.05 C- and 10 C-rate currents, respectively. Moreover, the synthesized composite LTO-NP/C composite material exhibits good cycling stability, and only 1.7% decrease in its specific capacity was observed after 200 charging–discharging cycles at 10 C-rate discharging current.

Ni/Porous Carbon-Based Composite Derived from Poplar Wood with Ultrabroad Band Microwave Absorption Performance

Electromagnetic wave (EMW) absorbers and electromagnetic shielding materials have attracted much attention in recent years. In this paper, Ni/wood-based porous carbon (WPC) composite material was prepared via morphology genetic method by using nickel chloride and poplar as raw material, The experimental results show that the microwave absorbing properties of the materials are related to the pyrolysis temperature, when the pyrolysis temperature settle at 700 °C, the minimum reflection loss of WPC-Ni can reach-60.4 dB with the thickness of 2.93 mm. Moreover, the effective absorption bandwidth has been greatly broadened up to 7.3 GHz when the thickness is 2.63 mm. The reason for such excellent wave absorbing performance is that the introduction of magnetic particles Ni and WPC-Ni regular straight channels improve impedance matching, the heterogeneous interface of Ni/ wood increases the polarization loss of electromagnetic waves. It is believed that this work can provide a new idea for the preparation of low-cost and high-efficiency broadband microwave absorber.

Maximizing visible Raman resolution of nanodiamond grains fabricated by coaxial arc plasma deposition through oxygen plasma etching optimization

Among the nondestructive carbon material characterization tools, the prominence of visible Raman spectroscopy has surged remarkably for many years due to its ability to explore a diverse array of carbon bonding configurations. However, to fully unlock the distinctive features concealed within carbon composite materials, additional specimen treatments or precise spectroscope calibrations are necessary. In the same regard, the tiny diamond grain size (5–10 nm) and the pronounced amount of sp2 carbon in the ultrananocrystalline diamond film represent major challenges in visible light excitation. In this work, we employ calibrated oxygen plasma reactive ion etching conditions to manifest the nanodiamond visible Raman signature from ultrananocrystalline diamond/amorphous carbon composite (UNCD/a‐C) films fabricated by coaxial arc plasma deposition. Upon plasma etching, the broad defect band in the visible Raman spectra converged toward the diamond characteristic Raman peak at 1332 cm−1. A detailed explanation of band components of the Raman spectra is extracted through peak fitting procedures. The results of Raman spectroscopy are further correlated with the electrical characteristics of the nitrogen‐doped UNCD/a‐C films due to the optimized oxygen plasma etching processes.