Production Of Carbon Nanofibers Research Articles

Effect of stabilization and carbonization treatment on the chemical and physical transformation of polyacrylonitrile (PAN) based electrospun carbon nanofibers

The present study delves into the production of carbon nanofibers (CNFs) utilising electrospun polyacrylonitrile (PAN) nanofiber mats, with a specific focus on the influence of oxidative stabilisation and carbonisation treatments. This research aims to thoroughly understand how variations in stabilisation time and temperature, as well as carbonisation temperature, impact the CNFs properties. These properties include fiber size, morphology, chemical and crystal structure transformation, thermal behaviour, and surface characteristics. Our methodology involved a detailed examination of the thermal treatment processes, where we observed a significant decrease in fiber size, though the surface morphology of the fibers remained largely unaffected. We employed Fourier-transform infrared (FTIR) spectroscopy to track the transformation of nitrile groups in PAN to imine groups, which indicated the progression of cyclisation reactions. Complementary analyses through differential scanning calorimetry (DSC) confirmed a high degree of these reactions, particularly at stabilisation temperatures extending to 250 °C and beyond. The cyclisation process was found to be complete during the carbonisation phase, at temperatures reaching 450 °C and above. Further, x-ray diffraction (XRD) patterns offered insight into the changes in the crystal structure, particularly in the packing of the d(002) spacing because of the stabilisation and carbonisation processes. This findings from this study not only elucidate the intricate process of CNFs production from electrospun PAN nanofiber mats but also highlight the critical factors that influence their final properties. These insights are invaluable for the development of advanced CNFs with tailored properties suitable for a range of applications, including but not limited to energy storage, electronics, and as supporting materials in various technological domains.

Unveiling the potential of cellulose, chitosan and polylactic acid as precursors for the production of green carbon nanofibers with controlled morphology and diameter

Carbon nanofibers (CNFs) are very promising materials with application in many fields, such as sensors, filtration systems, and energy storage devices. This study aims to explore the use of eco-friendly biopolymers for CNF production, finding novel, suitable and sustainable precursors and thus prioritising environmentally conscious processes and ecological compatibility.Polymeric nanofibers (PNFs) using cellulose acetate, polylactic acid, and chitosan as precursors were successfully prepared via electrospinning. Rheological testing was performed to determine suitable solution concentrations for the production of PNFs with controlled diameter and appropriate morphology. Their dimensions and structure were found to be significantly influenced by the solution concentration and electrospinning flow rate. Subsequently, the electrospun green nanofibers were subject to stabilisation and carbonisation to convert them into CNFs. Thermal behaviour and chemical/structural changes of the nanofibers during stabilisation were investigated by means of thermogravimetric analysis and Fourier-transform infrared spectroscopy, while the final morphology of the fibers after stabilisation and carbonisation was examined through scanning electron microscopy to determine the optimal stabilisation parameters. The optimal fabrication parameters for cellulose and chitosan-based CNFs with excellent morphology and thermal stability were successfully established, providing valuable insight and methods for the sustainable and environmentally friendly synthesis of these promising materials.

Zero-emission hydrogen production by CH4 pyrolysis over Ni/Ferrierite catalyst: Examination of the deactivated catalysts for electrical conductivity and H2 storage properties

An economic route for the generation of hydrogen and utilization of carbon nanofibers (CNFs) was achieved by CH4 cracking over 20 wt%Ni/FER catalyst. The deactivated catalyst demonstrated electrical conductivity and hydrogen storage properties. TEM images displayed open mouths of CNFs and XRF data showed nearly 70% of nickel was recovered from the deactivated catalyst. Impedance studies of the CNFs exhibit prominence as battery electrodes due to their significant conductivity in the presence of nickel. While the hydrogen storage capacity was around 0.151 mmol (gcat)−1 of H2 on the obtained CNFs, it was increased to 0.361 mmol (gcat)−1 upon Ni recovery from the CNFs. A seven-fold increase in the H2 storage of ∼0.862 mmol (gcat)−1 was obtained upon Li doping, exhibiting its distinct property as a hydrogen storage material. The fresh, reduced, used, and deactivated catalysts were characterized by BET-SA, H2-TPR, XRD, Raman spectroscopy, TEM, and H2 pulse chemisorption and Ni/FER was established as an economically viable catalyst for high rates of H2 and CNF production.

Nano-scaled polyacrylonitrile for industrialization of nanofibers with photoluminescence and microbicide performance

Nanofibers are investigated to be superiorly applicable in different purposes such as drug delivery systems, air filters, wound dressing, water filters, and tissue engineering. Herein, polyacrylonitrile (PAN) is thermally treated for autocatalytic cyclization, to give optically active PAN-nanopolymer, which is subsequently applicable for preparation of nanofibers through solution blow spinning. Whereas, solution blow spinning is identified as a process for production of nanofibers characterized with high porosity and large surface area from a minimum amounts of polymer solution. The as-prepared nanofibers were shown with excellent photoluminescence and microbicide performance. According to rheological properties, to obtain spinnable PAN-nanopolymer, PAN (12.5–15% wt/vol, honey like solution, 678–834 mPa s), thermal treatment for 2–4 h must be performed, whereas, time prolongation resulted in PAN-nanopolymer gelling or rubbering. Size distribution of PAN-nanopolymer (12.5% wt/vol) is estimated (68.8 ± 22.2 nm), to reflect its compatibility for the production of carbon nanofibers with size distribution of 300–400 nm. Spectral mapping data for the photoluminescent emission showed that, PAN-nanopolymer were exhibited with two intense peaks at 498 nm and 545 nm, to affirm their superiority for production of fluorescent nanofibers. The microbial reduction % was estimated for carbon nanofibers prepared from PAN-nanopolymer (12.5% wt/vol) to be 61.5%, 71.4% and 81.9%, against S. aureus, E. coli and C. albicans, respectively. So, the prepared florescent carbon nanofibers can be potentially applicable in anti-infective therapy.

Effect of Iron Chloride Addition on Softwood Lignin Nano-Fiber Stabilization and Carbonization.

This study presents the effect of iron chloride addition on the production of nanocarbon fibers from softwood Organosolv lignin. It was shown that adding 2% FeCl3 to the lignin solution before electrospinning to produce lignin nanofibers increased the thermal resistance of lignin fibers during stabilization. FTIR and XPS analyses of the lignin fibers stabilized with and without FeCl3 revealed that the temperature rate could be increased in the presence of FeCl3 from 1 to 3 °C/min. The optimal temperature to stabilize the lignin fibers was found to be 250 °C, as higher temperatures led to thermal degradation. Also, carbon fibers were successfully produced from pure softwood Organosolv lignin fibers. Carbonization tests were conducted under nitrogen and the best parameters were determined to be a ramp of 10 °C/min until 600 °C with a holding time of 2 h. Furthermore, the effect of 2% FeCl3 addition in the lignin solution was investigated during these processes. XPS analysis showed a 93% carbon content for fibers carbonized with and without FeCl3 addition, while SEM images revealed some surface roughness in fibers with FeCl3 after carbonization. These results confirm that FeCl3 addition influences the carbon nanofiber production.

Boosting effect of single-atom Sn on catalytic activity of Ni towards synthesis of carbon nanofibers from ethylene

Nickel and its alloys are widely used for the synthesis of carbon nanofibers via catalytic chemical vapor deposition of various hydrocarbons. In the present research, a series of Ni-Sn alloys with tin loading varied in a range from 0.1 to 25.0 at% were prepared and characterized. Alloying of nickel with a small amount of tin was found to accelerate significantly the catalytic process of ethylene decomposition accompanied by carbon deposition. For the NiSn(0.25) sample, the carbon yield reaches 195 g/gcat after 30 min at 550 °C. At the highest Sn loading (25.0 at%), the process is completely suppressed. A new mechanism explaining the observed interaction of ethylene with Ni-Sn alloys was proposed. Single-atom Sn species are responsible for the increased catalytic activity. A single-atom Ni-Sn alloy is considered an efficient catalyst with enhanced stability for the production of carbon nanofibers.

Effect of sodium promoters on Ni/Al2O3 catalyst for CO2 hydrogenation: The carbon fixation as carbon nanofiber and reverse-water gas reactions

Reducing CO2 emissions has become a critical priority in addressing the environmental impact of carbon dioxide. Technologies for CO2 fixation primarily involve carbon capture storage and utilization (CCSU) and chemical conversion, typically pursued along independent tracks. In our research, we have focused on developing a catalytic reaction for CO2 hydrogenation that integrates the benefits of both CCSU and chemical conversion. The use of sodium-promoted Ni/Al2O3 catalyst (NiNax/Al2O3) in the CO2 hydrogenation process exhibits a synergistic effect, leading to the simultaneous production of CO, CH4, and carbon nanofibers (CNFs). Notably, the conversion of CO2 into CNFs represents a novel approach for carbon fixation, in addition to the formation of CO and CH4. Importantly, the formation of CNFs on the NiNax/Al2O3 catalyst does not compromise its catalytic activity for CO2 hydrogenation to CO and CH4, which is a noteworthy finding. This bifunctional catalyst has the potential to offer significant advantages, including high CO production and the generation of valuable carbon materials. The CNFs are predominantly formed at the interfacial sites between NiNax and Al2O3. The formation process involves the reaction between H2 bound to Ni and adsorbed CO2, leading to the formation of hydrogen carbonate species, which subsequently give rise to CNFs. The reduction of CO2 to CNFs is facilitated by the transfer of electrons from Al3+ species to the interfacial sites between NiNax and Al2O3.

Large-scale solution blow spinning of flexible carbon nanofibers for the separation applications

Massive production of carbon nanofibers with low thermal conductivity and excellent properties has remained as an extremely challenging. Herein, solution blow spinning technology and textile post-treating technic were introduced to achieve the mass production of carbon nanofibers and its derivative products. Different types of materials (polyacrylonitrile and lignin) were utilized as the spinnable agent and carbon source. A comprehensive investigation was conducted into the influences of raw material components, blow spinning process, and high-temperature pyrolysis process on the performance of carbon nanofibers. Through controlling the solution flow rate (10–50 mL·h−1), different needle diameters (21–25 G) and high pressure airflow (0.2–0.4 MPa), organic solution could be effectively spined into organic fiber precursor. Importantly, with the assistant of textile rearrange and needle punching technics, loose organic sponge can be transformed into blanket with designed thicknesses and shapes. These SBS spined carbon fiber products exhibited ideal compressional resilience ability (up to 60 %), adsorption of toluene, and thermal insulation performance (0.037 W·(m·K)-1).

Effect of Cu on Performance of Self-Dispersing Ni-Catalyst in Production of Carbon Nanofibers from Ethylene

The development of effective catalysts for the pyrolysis of light hydrocarbons with the production of carbon nanomaterials represents a relevant direction. In the present work, the influence of copper addition on performance of a self-dispersed Ni-catalyst and structural features of the obtained carbon nanofibers (CNFs) was studied. The precursors of Ni and Ni-Cu catalysts were prepared by activation of metal powders in a planetary mill. During contact with the C2H4/H2 reaction mixture, a rapid disintegration of the catalysts with the formation of active particles catalyzing the growth of CNFs has occurred. The kinetics of CNF accumulation during ethylene decomposition on Ni- and Ni-Cu catalysts was studied. The effect of temperature on catalytic performance was explored and it was shown that introduction of copper promotes 1.5–2-fold increase in CNFs yield in the range of 525–600 °C; the maximum CNFs yield (100 g/gcat and above, for 30-min reaction) is reached on Ni-Cu-catalyst at 575–600 °C. A comparative analysis of the morphology and structure of CNF was carried out using electron microscopy methods. The growth mechanism of carbon filaments in the shape of “railway crossties” on large nickel crystals (d > 250 nm) was proposed. It was found that the addition of copper leads to a decrease in the bulk density of the carbon product from 40–60 to 25–30 g/L (at T = 550–600 °C). According to the low-temperature nitrogen adsorption data, specific surface area (SSA) of CNF samples (at T < 600 °C) lies in the range of 110–140 m2/g, regardless of the catalyst composition; at T = 600 °C the introduction of copper contributed to an increase in the specific surface of CNF by 100 m2/g.

Decomposition of light hydrocarbons on a Ni-containing glass fiber catalyst

The work is devoted to the study of the novel process of catalytic decomposition of light hydrocarbons on a catalyst at temperatures of 550 °С and 600 °C at various pressures. The CVD process is a new COx-free approach for hydrogen production. A glass fiber fabric was used as a catalyst, which was preliminarily modified by the application of additional outer layers of NiO and porous silica. A technical mixture of propane and butane was used as feedstock. The main purpose is to investigate the effects of pressure and temperature on the production of hydrogen and carbon nanofibers over a glass-based catalyst. As a result of the decomposition of the mixture, the yield of hydrogen was 266–848 L/gcat, and that of carbon nanofibers was 3–10 g/gcat. Increasing the pressure of propane-butane mixture decomposition led to an increase of the catalyst lifetime. The highest yield of hydrogen and carbon nanofibers was achieved at 1 bar and 600 °C.

Methane conversion to H2 and carbon nanofibers over supported Ni catalysts: A sustainable process through utilization of deactivated catalysts

AbstractThe renewable resource such as rice husk has been utilized to synthesize Hβ zeolite as a support for Ni catalysts for the production of clean hydrogen and carbon nanofibers (CNFs) by CH4 cracking at 550°C without any CO or CO2 formation. Hydrogen production rates and area of surface Ni are in good correlation, implying the optimum Ni loading of 25 wt % that demonstrated better hydrogen yields and CNFs. The electrochemical properties of the deactivated catalysts indicated that they were near semiconducting in nature, showing future prospects as carbon electrode materials. The physicochemical characteristics of the fresh, reduced, and used catalysts were rationalized by BET surface area, p‐X‐ray diffraction, temperature programmed reduction using H2, SEM, TEM, H2‐pulse chemisorption, and Raman spectroscopic analyses in conjunction with hydrogen rates.

Synthesis and structure of NiCu and NiAl electroexplosive nanoparticles for production of carbon nanofibers

Synthesis and structure of NiCu and NiAl electroexplosive nanoparticles for production of carbon nanofibers

Efficient Production of Segmented Carbon Nanofibers via Catalytic Decomposition of Trichloroethylene over Ni-W Catalyst.

The catalytic utilization of chlorine-organic wastes remains of extreme importance from an ecological point of view. Depending on the molecular structure of the chlorine-substituted hydrocarbon (presence of unsaturated bonds, intermolecular chlorine-to-hydrogen ratio), the features of its catalytic decomposition can be significantly different. Often, 1,2-dichloroethane is used as a model substrate. In the present work, the catalytic decomposition of trichloroethylene (C2HCl3) over microdispersed 100Ni and 96Ni-4W with the formation of carbon nanofibers (CNF) was studied. Catalysts were obtained by a co-precipitation of complex salts followed by reductive thermolysis. The disintegration of the initial bulk alloy driven by its interaction with the reaction mixture C2HCl3/H2/Ar entails the formation of submicron active particles. It has been established that the optimal activity of the pristine Ni catalyst and the 96Ni-4W alloy is provided in temperature ranges of 500-650 °C and 475-725 °C, respectively. The maximum yield of CNF for 2 h of reaction was 63 g/gcat for 100Ni and 112 g/gcat for 96Ni-4W catalyst. Longevity tests showed that nickel undergoes fast deactivation (after 3 h), whereas the 96Ni-4W catalyst remains active for 7 h of interaction. The effects of the catalyst's composition and the reaction temperature upon the structural and morphological characteristics of synthesized carbon nanofibers were investigated by X-ray diffraction analysis, Raman spectroscopy, and electron microscopies. The initial stages of the carbon erosion process were precisely examined by transmission electron microscopy coupled with elemental mapping. The segmented structure of CNF was found to be prevailing in a range of 500-650 °C. The textural parameters of carbon product (SBET and Vpore) were shown to reach maximum values (374 m2/g and 0.71 cm3/g, respectively) at the reaction temperature of 550 °C.

Correlation on synthesis design and surface modification towards properties and applications of carbon nanofibers and carbon nanofibers based nanocomposites

AbstractWith the recent advancement in nanoscience and nanotechnology, carbon nanomaterials have achieved great attention owing to their unique physico‐chemical, mechanical, thermal, and electrical properties. Amongst carbon nanomaterials, carbon nanofibers (CNF) depict a high surface‐to‐volume ratio, enhanced porosity, high mechanical strength, and low weight (light). Carbon nanofibers‐based nanocomposites (CNFN) have been developed for diverse applications. This review illustrates the recent progress in (a) the CNF synthesis via chemical vapor deposition (CVD) or electrospinning, (b) their functionalization with metals and metal oxides nanoparticles, polymers, alloys, and (c) their applications in environmental, industrial, and biomedical domains. Moreover, this study will be helpful for readers to understand CNF production, including the latest trends and fabrication techniques to obtain efficient, cost‐effective, eco‐friendly CNFN, having enhanced surface area with maximum selectivity, reproducibility, and multi‐potential applications.

Preparation of Ni–Cu Catalyst for Carbon Nanofiber Production by the Mechanochemical Route

Preparation of Ni–Cu Catalyst for Carbon Nanofiber Production by the Mechanochemical Route

Porous Co-Pt Nanoalloys for Production of Carbon Nanofibers and Composites.

The controllable synthesis of carbon nanofibers (CNF) and composites based on CNF (Metals/CNF) is of particular interest. In the present work, the samples of CNF were produced via ethylene decomposition over Co-Pt (0-100 at.% Pt) microdispersed alloys prepared by a reductive thermolysis of multicomponent precursors. XRD analysis showed that the crystal structure of alloys in the composition range of 5-35 at.% Pt corresponds to a fcc lattice based on cobalt (Fm-3m), while the CoPt (50 at.% Pt) and CoPt3 (75 at.% Pt) samples are intermetallics with the structure P4/mmm and Pm-3m, respectively. The microstructure of the alloys is represented by agglomerates of polycrystalline particles (50-150 nm) interconnected by the filaments. The impact of Pt content in the Co1-xPtx samples on their activity in CNF production was revealed. The interaction of alloys with ethylene is accompanied by the generation of active particles on which the growth of nanofibers occurs. Plane Co showed low productivity (~5.5 g/gcat), while Pt itself exhibited no activity at all. The addition of 15-25 at.% Pt to cobalt catalyst leads to an increase in activity by 3-5 times. The maximum yield of CNF reached 40 g/gcat for Co0.75Pt0.25 sample. The local composition of the active alloyed particles and the structural features of CNF were explored.

Effect of hydrogen flow rate on the synthesis of carbon nanofiber using microwave-assisted chemical vapour deposition with ferrocene as a catalyst

Carbon nanostructure materials are becoming of considerable commercial importance, with interest growing rapidly over the decade since the discovery of carbon nanofibers. In this study, a new novel method is introduced to synthesize the carbon nanofibers by gas-phase, where a single-stage microwave-assisted chemical vapour deposition approach is used with ferrocene as a catalyst and acetylene and hydrogen as precursor gases. Hydrogen flow rate plays a significant role in the formation of carbon nanofibers, as being the carrier and reactant gas in the floating catalyst method. The effect of process parameters such as microwave power, radiation time and gas ratio of C2H2/H2 was investigated statistically. The carbon nanofibers were characterized using scanning and transmission electron microscopy and thermogravimetric analysis. The analysis revealed that the optimized conditions for carbon nanofibers production were microwave power (1000 W), radiation time (35 min) and acetylene/hydrogen ratio (0.8). The field emission scanning electron microscope and transmission electron microscope analyses revealed that the vertical alignment of carbon nanofibers has tens of microns long with a uniform diameter ranging from 115 to 131 nm. High purity of 93% and a high yield of 12 g of CNFs were obtained. These outcomes indicate that identifying the optimal values for process parameters is important for synthesizing high quality and high CNF yield.

Carbon nanofibers derived from cellulose via molten-salt method as supercapacitor electrode

Carbon nanofibers (CNFs) have been paid much attention as supercapacitor electrode due to outstanding chemical stability, high electron transfer rate and large specific surface area. However, the preparation process of CNFs is always stalemated in electrospinning, heat stabilization and carbonization. The problems of solvent pollution in the electrospinning process, complex process and high energy consumption in conventional carbonization process can't be solved. Herein, CNFs have been innovatively prepared from nanofibrillated cellulose by the molten-salt method (NaCl/NaOH). Molten salt penetrates between the fibers, separates and activates the fibers. The obtained carbon nanofibers remain developed branching structures and have a large specific surface area (899 m2 g−1). The electrical properties are tested in a symmetrical two-electrode system. The specific capacitance is 150 F g−1 at the current density of 1 A g−1. Low equivalent series resistance (1.13 Ω) indicates that it has high electrode conductivity. This study has taken into account energy conservation, environmental protection, recyclability and simplified preparation process, which has a very far-reaching significance for the industrial production of CNFs.

Technology for Producing Hydrogen and Carbon Nanofibers from Natural Gas

Technology for Producing Hydrogen and Carbon Nanofibers from Natural Gas

The Production of Carbon Nanofiber on Rubber Fruit Shell-Derived Activated Carbon by Chemical Activation and Hydrothermal Process with Low Temperature.

Recently, the conversion of biomass into carbon nanofibers has been extensively studied. In this study, carbon nanofibers (CNFs) were prepared from rubber fruit shell (RFS) by chemical activation with H3PO4, followed by a simple hydrothermal process at low temperature and without a vacuum and gas catalyst. XRD and Raman studies show that the structure formed is an amorphous graphite formation. From the thermal analysis, it is shown that CNFs have a high thermal stability. Furthermore, an SEM/TEM analysis showed that CNFs’ morphology varied in size and thickness. The obtained results reveal that by converting RFS into an amorphous carbon through chemical activation and hydrothermal processes, RFS is considered a potential biomass source material to produce carbon nanofibers.