Synthesis Of Carbon Nanofibers Research Articles

Electrospun carbon nanofibers embedded with heterostructured NiFe2O4/Fe0.64Ni0.36 nanoparticles as an anode for high-performance lithium-ion battery

Binary transition metal compounds exhibit promising application potential as anode materials in the field of lithium-ion batteries (LIBs) due to their high theoretical specific capacity. However, their poor electrical conductivity and drastic volume expansion during charge and discharge pocesses limit their high-performance applications. Herein, we have synthesized carbon nanofibers (CNFs) loaded with heterostructured NiFe based nanoparticles (NiFe2O4/Fe0.64Ni0.36@CNFs) using electrospinning, and explore their cyclic stability and rate performances. By subjecting the electrospun membranes to thermal treatment at different annealing temperatures, three distinct phases of NiFe compounds embedded in CNFs, i.e., NiFe2O4 (400 °C), NiFe2O4/Fe0.64Ni0.36 (500 °C) and Fe0.64Ni0.36 (800 °C), are obtained. When they are used as anode materials, the electrochemical properties are investigated. The NiFe2O4/Fe0.64Ni0.36@CNFs anode material exhibits the best cycling and rate performances, with a capacity of 431.1 mAh g−1 achieved after 200 cycles at a current density of 0.2 A g−1. Moreover, its specific capacities are 558.9, 400.1, 272.4, 178.1 and 89.5 mAh g−1 at current densities of 0.1, 0.2, 0.5, 1.0 and 2.0 A g−1, respectively. As the current density returns to 0.1 A g−1, its specific discharge capacity can reach 527.5 mAh g−1. The excellent cycling and rate performances of NiFe2O4/Fe0.64Ni0.36@CNFs are mainly attributed to the following reasons: i) the carbon fibers can effectively alleviate volume expansion and structural stress during cycling; ii) Fe0.64Ni0.36 alloy can inhibit the formation of lithium dendrites and effectively reduce the nucleation overpotential of metallic lithium, thereby improving the electrochemical stability; iii) the heterostructure can improve electrochemical properties through the synergistic interaction between NiFe2O4 and Fe0.64Ni0.36. The catalytic Fe0.64Ni0.36 not only facilitate the conversion reaction of NiFe2O4, resulting in the high capacity, but also increase the conductivity of the material. This work offers a feasible strategy to significantly improve the electrochemical performance of binary metal compounds, paving the way for their practical applications in the high-performance LIBs.

Energy-efficient sintering-free Chemically synthesized carbon nanofibers for high-performance supercapacitors

This work introduces a cost-effective method to synthesize carbon nanofibers (CNFs) at a lower temperature (∼100 °C), addressing the synthesis cost and precursor selection challenges associated with traditional methods requiring temperatures of ⁓3000 °C. Acid-etched banana fibers served as sustainable precursors, while KClO3 acted as a liquid carbonization medium. The resulting CNFs (referred MCCNFs), exhibited hollow structures with intertwined tubular morphology (OD ∼20–40 nm and ID∼ 5–10 nm). They possessed a hexagonal porous structure (P63/mmc) with a high specific surface area (152.09 m2g-1), significant pore volume (0.459 ccg−1), and impressive tensile strength exceeding 2.71 TPa. Smaller intensity ratio of D and G bands (0.396) confirmed their purity and structural integrity. MCCNFs displayed semi-metallic behaviour with superior electrical conductivity (0.0386 S-m−1), validated by ab initio electronic band structure calculations. UV–vis absorption spectra revealed a linear band structure. Notably, MCCNFs displayed a record-breaking capacitance of 1412.5 Fg-1 at 5 Ag-1, making them promising for supercapacitor electrode applications. Furthermore, these CNFs were used to fabricate a flexible all-solid-state supercapacitor, successfully powering 6 LEDs for 10 s. Hence, this work set a pave for low-cost, low-temperature synthesis of CNFs having superior physical and chemical properties and immense promise for advancing energy storage applications.

Molten Carbonate Transformation of the Green House Gas CO2 to Graphitic Nanomaterials

CO2 is a highly stable molecule. This stability had been considered an insurmountable barrier to Its transformative removal from its role as a greenhouse case. The C2CNT® (CO2 To Carbon Nanomaterial Technology) process breaks through this barrier by using an energetic (high temperature), carbon rich (molten carbonate), transition metal nucleated environment, electrolytically splitting of CO2 to graphitic carbon nanomaterials (and O2). Built from the same fundamental graphene structure as graphite, which has a geologic lifetime, these nanocarbons can permanently bind the transformed CO2 to mitigate global warming. Their value arises from the properties of graphene such as high strength and conductivity, solid lubrication, electronic and catalytic activity tuned by distinctive 0D, 1D and 2D morphologies.The value of these nano graphitic carbons arises from the unique properties of graphene such as exceptional strength, high conductivity, solid lubrication, electronic and catalytic activity as modified by their distinctive 0D, 1D and 2D shapes. These nanocarbons are useful in a range of applications in the carbon fiber, polymer, electronic, medical, transportation, steel, cement and power sectors.The C2CNT® technology received the 2021 Carbon XPRIZE XFactor award for producing the most valuable product from CO2. and builds out the C2CNT technology into a Genesis Device® CCUS (Carbon Capture, Utilization and Storage) plant. A Genesis Device® CCUS demonstration plant has been built at the in Calgary, and a large-scale Genesis Device® CCUS plant, the GC3 project, is scheduled in Edmonton, producing 7,500 tonnes of carbon nanotubes transforming the CO2 emission at the Genessee power plant. Some of the 30 C2CNT® related publications are presented at: https://carboncorp.org/climate-change-solutionThese publications include:“STEP generation of energetic molecules: A solar chemical process to end anthropogenic global warming” Licht, J. Phys. Chem, C, 113, 16283, 2009. "Efficient Solar-Driven Synthesis, Carbon Capture, and Desalinization, STEP: Solar Thermal Electrochemical Production of Fuels, Metals, Bleach" Licht, Advanced Materials,47, 5592 (2011).The discovery of the electrochemical nucleated growth of graphitic nanocarbons in:"One-pot synthesis of carbon nanofibers from CO2",Ren, Li, Lau, Urbina, LichtNano Letters, 15, 6142, 2015.CO2 isotopic tracking to the electrolytic splitting products: “Tracking airborne CO2 mitigation and low cost transformation into valuable carbon nanotubes,” Ren, Licht,Scientific Reports,6, 27760-1, 2016."Carbon Nanotube Wools Made Directly from CO2 By Molten Electrolysis: Value Driven Pathways to Carbon Dioxide Greenhouse Gas Mitigation," Materials Today Energy, Johnson, Ren, Lefler, Licht, Vicini, Liu, Licht, 5, 230,2017.“Recent Advances in Solar Thermal Electrochemical Process (STEP) for Carbon Neutral Products & High Value Nanocarbons,” Ren, Yu, Peng, Lefler, Li, Licht, Accounts of Chemical Research, 52, 3177(2019).“Amplified CO2 greenhouse gas removal with C2CNT carbon nanotube-material composites”,Licht, Xinye, Licht, Wang, Swesi, Chan, Materials Today Sustainability, 6, 100023(2019). Wang, Sharif, Liu, Licht, Lefler, Licht,“Magnetic carbon nanotubes: Carbide nucleated electrochemical growth of ferromagnetic CNTs from CO2,” Wang, Sharif, Liu, Licht, Lefler, Licht, Journal of CO2 Utilization, 40, 101282020.“The green synthesis of exceptional braided, helical carbon nanotubes and nanospiral platelets made directly from CO2,” Liu, Licht, Licht, Materials Today Chemistry , 22, 100529 (2021).Figure top: SEM of nanocarbon allotropes. Top row (from left to right): conical CNF, nano-bamboo, nano-pearl, Ni coated CNT, nano-flower, nano-dragon. Middle row: nano-rod, nano-belt, nano-onion, hollow nano-onion, and nano-tree. Bottom row carbon nanotube, nano-scaffold, nano-platelet, graphene, nano-helices. From: Control of the electrochemical conditions tuning C2CNT® to selectively produce 17 unusual nanocarbons is described in: “Controlled Growth of Unusual Nanocarbon Allotropes by Molten Electrolysis of CO2”, Liu, Licht, Wang, Licht, Catalysts, 12, 125, 2022:Figure Bottom: TEM and HAADF of high purity, high yield carbon nanotubes synthesized by electrolytic splitting of CO2 in 770°C Li2CO3. TEM; scale bars left to right top: 20 nm & 1 nm. 2nd row 100, 5, 5 & 1 nm. 3rd row 100 or 50 nm. Bottom row 20, 1 & 1 nm. From “Controlled Transition Metal Nucleated Growth of Carbon Nanotubes by Molten Electrolysis of CO2”, Liu, Licht, Wang, Licht, Catalysts, 12, 137, 2022: Figure 1

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.

Carbon Nanowalls as Anode Materials with Improved Performance Using Carbon Nanofibers.

In this paper, a new synthesis of carbon nanofibers (CNFs)/carbon nanowalls (CNWs) was performed to improve the characteristics of anode materials of lithium-ion batteries by using the advantages offered by CNWs and CNFs. Among the carbon-based nanomaterials, CNWs provide low resistance and high specific surface area. CNFs have the advantage of being stretchable and durable. The CNWs were grown using a microwave plasma-enhanced chemical vapor deposition (PECVD) system with a mixture of methane (CH4) and hydrogen (H2) gases. Polyacrylonitrile (PAN) and N,N-Dimethyl Formamide (DMF) were stirred to prepare a solution and then nanofibers were fabricated using an electrospinning method. Heat treatment in air was then performed using a hot plate for stabilization. In addition, heat treatment was performed at 800 °C for 2 h using rapid thermal annealing (RTA) to produce CNFs. A field emission scanning electron microscope (FE-SEM) was used to confirm surface and cross-sectional images of the CNFs/CNWs anode materials. Raman spectroscopy was used to examine structural characteristics and defects. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and constant current charge/discharge tests were performed to analyze the electrical characteristics. The synthesized CNFs/CNWs anode material had a CV value in which oxidation and reduction reactions were easily performed, and a low Rct value of 93 Ω was confirmed.

Çevre Dostu Karbon Nano Fiberlerin Kimyasal Buhar Biriktirme Tekniği Kullanılarak Metanol ile Sentezlenmesi

This study aims to investigate the suitability of methanol as a carbon source for the synthesis of carbon nanofibres (CNFs), currently used in wastewater, water, and air purification systems, by chemical vapor deposition (CVD) in the presence of NiO catalyst. Experimental studies were carried out in a tube furnace under isothermal conditions. Catalyst particles were loaded onto silicon wafers with orientation by dip coating to grow CNFs. The reduction behavior of nickel oxide powder at 1000 K under non-isothermal and isothermal conditions was investigated before CNF synthesis studies. The percentage reduction of nickel oxide powder under non-isothermal conditions was 82.03%. The percentage reduction under isothermal conditions for 30 min was 78.03%. The experimental result obtained is very close to the theoretical value (78.57%). During CNF synthesis experiments, it was observed that CNF formation was not achieved at temperatures of 1000 - 1100 K due to the poor thermal decomposition of methanol. Pyrolysis of methanol increased with increasing synthesis temperature (1200 K), which promoted the synthesis of CNFs. SEM analysis revealed morphologically dense CNF formation under isothermal conditions for 20 min at 1300K synthesis temperature.

Low-temperature Synthesis of Carbon Nanofibers/graphite Felt Composites Under Contactless Induction Heating

In this report induction heating was used for the catalytic chemical vapor decomposition synthesis of carbon nanofibers (CNFs) on Ni-based catalyst. The CNFs were produced with a high yield at a relatively low temperature compared to that observed for conventional heating through convection and conduction. The process also occurred in the absence of secondary toxic organic compounds, formed through side reaction in the high temperature gas-phase or through decomposition on the hot wall of reactor as encountered with traditional Joule heating mode. The improved CNFs yield under induction heating was attributed to the high reaction temperature control thanks to the high temperature regulation rate provided by the induction heating coil. The local heating of the nickel nanoparticles by the electromagnetic field could also contribute to the improvement of the CNFs yield. The results obtained indicate that inductive heating mode could be of great interest for improving the heat transfer in catalytic processes and also to reduce the problem of gradient temperature occurring inside the catalyst bed during the operating of highly exothermic or endothermic processes. It is expected that such electricity-driven heating mode could have contributed in an efficient way toward the electrification of different catalytic processes in order to reduce the associated carbon footprint.

Synthesis of Ilmenite Nickel Titanite-Supported Carbon Nanofibers Derived from Polyvinylpyrrolidone as Photocatalyst for H2 Production from Ammonia Borane Photohydrolysis.

The present study involves the synthesis of photocatalytic composite nanofibers (NFs) comprising ilmenite nickel titanite-supported carbon nanofibers (NiTiO3/TiO2@CNFs) using an electrospinning process. The photocatalytic composite NFs obtained were utilized in hydrogen (H2) production from the photohydrolysis of ammonia borane (AB). The experimental findings show that the photocatalytic composite NFs with a loading of 25 mg had a good catalytic performance for H2 generation, producing the stoichiometric H2 in 11 min using 1 mmol AB under visible light at 25 °C and 1000 rpm. The increase in catalyst load to 50, 75, and 100 mg leads to a corresponding reduction in the reaction time to 7, 5, and 4 min. The findings from the kinetics investigations suggest that the rate of the photohydrolysis reaction is directly proportional to the amount of catalyst in the reaction system, adhering to a first-order reaction rate. Furthermore, it was observed that the reaction rate remains unaffected by the concentration of AB, thereby suggesting a reaction of zero order. Increasing the reaction temperature results in a decrease in the duration of the photohydrolysis reaction. Furthermore, an estimated activation energy value of 35.19 kJ mol-1 was obtained. The composite nanofibers demonstrated remarkable and consistent effectiveness throughout five consecutive cycles. The results suggest that composite NFs possess the capacity to function as a feasible substitute for costly catalysts in the process of H2 generation from AB.

Sustainable and Green Synthesis of Carbon Nanofibers from Date Palm Residues and Their Adsorption Efficiency for Eosin Dye

This work investigates the prospective usage of dried date palm residues for eosin Y and eosin B (ES-Y and ES-B) dye removal from an aqueous solution. A green synthesis route is utilized to prepare carbon nanofibers (CNFs) from date palm residues. We study the characteristics of carbon nanomaterials based on their composition and morphology. The characterization includes different types of instruments such as a Fourier-Transform Infrared Spectroscopy (FTIR), Brunauer Emmett Teller (BET), and Scanning Electron Microscopy (SEM). Batch mode experimentations are conducted and studied utilizing various significant factors such as the dose of the adsorbent, solution pH, contact time, and the initial quantity of eosin molecules as a pollutant. The dye adsorption capability improves with an increasing adsorbent dose of up to 40 mg of CNFs. The adsorption of dyes onto CNFs achieves equilibrium in around 60 h, whereas the optimal starting dye concentration in this study is 50 ppm. Further, to study the under-investigated toxic molecules’ adsorption process mechanism on the nanomaterials’ active sites, we introduce kinetic models involving pseudo-first-order, pseudo-second-order, and models based on intra-particle diffusion. Langmuir and Freundlich’s isotherms are considered to study the equilibrium isotherms, and the Langmuir isotherm model deals considerably with the attained experimentation results.

A dual-template strategy assisted synthesis of porous coal-based carbon nanofibers for supercapacitors

The electrospun carbon nanofibers (ECNFs) with the advantages of facile preparation method, excellent electrical conductivity and ease compounding are expected to be excellent electrode materials for supercapacitors. However, the tiny specific surface area and low specific capacitance prevent the further development of carbon nanofibers. In this work, the porous coal-based carbon nanofibers (PCCNFs-2) are fabricated via a facile dual-template method, which can be directly employed as a flexible electrode material for supercapacitors without the addition of any conductive agents and binders. As a result, the flexible self-supporting electrode (PCCNFs-2) achieves a specific capacitance of 262.0 F g−1 at a current density of 1 A g−1, excellent rate performance (81.0 % capacitance retention at a current density of 20 A g−1) and excellent cycling stability (after 10,000 cycles, 124 % capacity retention at 2 A g−1). Furthermore, the aqueous symmetrical supercapacitors (SCs) assembled with melamine foam as the storage electrolyte at an operating voltage of 1.2 V achieved an energy density of 18.5 Wh kg−1 at a power density of 150.5 W kg−1. The effective construction of this porous carbon nanofiber assures the structural integrity and achieves excellent electrochemical performance of the electrode material, which develops a new strategy for efficient utilization of porous coal-based carbon nanofibers in supercapacitors.

Facile synthesis of nickel-decorated multidimensional carbon nanofibers via oxygen plasma activation for non-enzymatic acetaminophen sensing

Acetaminophen (AMP), the most commonly used drug for pain and fever, has very low side effects. However, due to its widespread use, emissions from manufacturing plants and daily life adversely affect various animals and plants, so it is necessary to precisely monitor the concentration. This research suggests the manufacture of composite carbon nanofibers with carbon nanotubes containing nickel particles (Ni–CNT@CNF), and applying the material as an electrochemical sensor electrode material that is capable of measuring AMP. In detail, an oxygen functional group is introduced into the PVP layer by using an O2 vacuum plasma process in a polymer fiber formed by electrospinning a mixed solution of PAN and a PVP including a nickel precursor. The carbon nanotubes are then induced to grow by the catalytic reaction of nickel and decomposed PVP during the carbonization. The Ni–CNT@CNF-based sensor electrode has a low detection limit (0.5 nM), and a wide detection range of (1 nM–70 μM) for AMP molecules. In addition, comparison of sensitivity with other biologically active metabolites demonstrated the excellent selectivity of the sensor electrode.

Characteristics and electrochemical performances of nickel@nano‐silicon/carbon nanofibers composites as anode materials for lithium secondary batteries

AbstractSi is a next‐generation ideal anode material for Li‐ion batteries (LIBs) because of its high‐theoretical capacity (4200 mAh/g) and natural abundance. However, severe volume expansion and unstable solid electrolyte interface (SEI) film formation during lithiation/delithiation, and poor electron conductivity have significantly restricted the commercial application of Si. In this study, transition metal‐coated Si was synthesized and used as the anode material of LIBs. The transition metal salt of Ni was dissolved in an aqueous solution and used to coat the metal surface of Si nanoparticles. The coating was achieved by dropwise addition of metal solutions into Si dispersions. Thereafter, carbon nanofibers (CNFs) were grown on the transition metal‐coated Si nanoparticles via chemical vapor deposition method. The morphologies, compositions, and crystal quality of transition metal@Si/CNFs composites were characterized by transmission electron microscopy, scanning electron microscopy, x‐ray diffraction, Raman spectroscopy, and thermogravimetric analysis. The electrochemical characteristics of the hybrid anodes were investigated using a coin cell and battery tester. Voltage profile measurements at 0.1 A/g of 0.02 M‐Ni@Si/CNFs composite showed satisfactory initial Coulombic efficiency of 85.6%; 0.01 M‐Ni@Si/CNFs composite exhibited high initial capacity of 1300.9 mAh/g retained to 828.4 mAh/g after 100 cycles, corresponding to 63.7% capacity retention. Even at high current densities, the 0.02 M‐Ni@Si/CNFs composite delivered 342.78 mAh/g of capacity at 5 A/g. This work realizes a Si‐based hybrid anode from Ni‐coated Si catalyst used for direct CNFs synthesis with a stable SEI layer, superior initial Coulombic efficiency with satisfactory cycle and rate performance suitable for commercialized advanced battery applications.

Temperature optimization in a gas reactor for the synthesis of carbon nanofibers: A numerical approach

The synthesis of carbon nanofibers (CNF) in a gas reactor requires specific thermal conditions. The temperature at which the process is carried out determines the final structure of the CNF, being 600 °C (873.15 K) the optimal temperature. In this work we address the modeling and numerical simulation of flow and temperature for a mixture of gases in a 0.09 m of diameter and 1 m long reactor to optimize the temperature inside it. The study is focused on determining appropriate temperatures at the reactor shell, to assure optimal temperatures at the catalyst support device where the reaction of formation of CNF takes place. Different locations of the support device are considered: the position on the left is at 17 cm from the reactor entrance; the central position is in the middle of the reactor, at 44 cm from both, the entrance and the outlet of the reactor; and the position at the right is at 17 cm from the outlet. We show that the location on the left is not suitable as it requires an impracticable temperature at the reactor shell. Optimal temperatures at the reactor shell can be found when the support device is located at the center of the reactor or closer to the outlet, being the latter more convenient for energy efficiency, as it requires a lower temperature at the shell. Simulations are performed using COMSOL Multiphysics. Results are interesting for laboratory experiments in order to control the temperature required for the optimal formation of these important industrial nanomaterials.

BIOGENIC CARBON NANOFIBER SYNTHESIZED FROM AGRO-WASTE FOR REMOVAL OF HEAVY-METAL FROM WASTEWATER

The advent of inexorable human, and industrial activities as well as the input of nature has impacted the environment by releasing Heavy Metals into the aquatic system. Hence, the physical removal of hazardous HM remains a demand of the day. This review envisages the use of agro-waste with the incorporation of nanotechnology for the removal of HM from aquatic systems. The focus is on plant parts, plant metabolites, and plant-cellulose-derived Carbon Nanofibers (CNF) as materials used for the removal of Heavy Metals. Owing to their high surface area, high mechanical strength, greater chemical reactivity due to the presence of dangling bonds, non-toxicity, high porosity,channel-like morphology, and lower costas the precursor, energy-efficient production; makes CNF an effective adsorbent of Heavy Metals.CNF synthesized from agro-waste and plant-metabolite to adsorb Heavy Metals; as well as acts as a filtration base has been touched upon with the hope of bridging the gap between ever-increasing demand and available clean water. A brief introduction to the CNF, its structure, properties as well as common methods of synthesis of CNF is given. Moreover, Physico-Chemical and Biological methods that are being used is also touched upon. The article suggests the need for innovative, low-cost, and environmentally friendly surface modification techniques and the use of agro-waste-derived CNF for the removal of HM from water.

Rational synthesis of chitin-derived nitrogen-doped porous carbon nanofibers for efficient polysulfide confinement

Rational synthesis of chitin-derived nitrogen-doped porous carbon nanofibers for efficient polysulfide confinement

Solution Combustion Synthesis of Ni/Al2O3 Catalyst for Methane Decomposition: Effect of Fuel

The synthesis of a 90% Ni/Al2O3 catalyst via solution combustion synthesis with various fuels was studied in this work. Catalysts with a high content of the active component (i.e., nickel) were obtained as a result of the combustion of Ni(NO3)2·6H2O and Al(NO3)3·9H2O mixtures with fuel. The fuels, such as hexamethylenetetramine, glycine, urea, starch, citric acid, and oxalic acid, were investigated. The synthesis was carried out in a furnace, with the temperature being raised from room temperature to 450 °C at a rate of 1 °C per min. The paper evaluates the efficiency of fuels and their effect on the structure and properties of catalysts, as well as their catalytic activity. The catalyst was used for the synthesis of hydrogen and carbon nanofibers by methane decomposition at 1 bar and 550 °C. The catalysts were tested in a vertical flow reactor without preliminary reduction. The obtained samples of catalysts and carbon nanomaterials were studied by transmission electron microscopy, low-temperature nitrogen adsorption, and X-ray diffraction. The highest activity of the catalyst was obtained when citric acid was used as a fuel. The specific yields of hydrogen and carbon nanofibers were 17.1 mol/gcat and 171.3 g/gcat, respectively. Catalytic decomposition of methane led to the formation of cup-stacked carbon nanofibers.

In-Situ Synthesis of PN-Doped Carbon Nanofibers for Single-Atom Catalytic Hydrosilylation.

Single-atom catalysts have become a popular choice in various catalysis applications, as they take advantages of both homogeneous catalysis (e.g., high efficiency) and heterogeneous catalysis (e.g., easy catalyst recovery). The atom support plays an indispensable role in anchoring atomic species and interplaying with them for ultimate catalytic performance. Therefore, development of new support materials for superior catalysis is of great importance. Here the synthesis of carbon nanofibers based on the reaction between phosphorus pentoxide (P2 O5 ) and N-methyl-2-pyrrolidone (NMP) is reported. The underlying reaction process is systematically investigated by Fourier-transform infrared(FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. The carbon nanofibers have interesting PN units in their chemical structure, which act as anchoring sites for the single-atom catalyst. The Pt atoms anchoring carbon nanofibers exhibit high activity for hydrosilylation with a turnover frequency (TOF) of 9.2×106 h-1 and a selectivity of >99%. This research affords not only a new in situ chemical strategy to synthesize multiatom doped carbon nanofibers but also presents a potential superior support in catalysis, which opens a hopeful window in materials chemistry and catalysis applications.

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.

Synthesis of Chlorine- and Nitrogen-Containing Carbon Nanofibers for Water Purification from Chloroaromatic Compounds

Chlorine- and nitrogen-containing carbon nanofibers (CNFs) were obtained by combined catalytic pyrolysis of trichloroethylene (C2HCl3) and acetonitrile (CH3CN). Their efficiency in the adsorption of 1,2-dichlorobenzene (1,2-DCB) from water has been studied. The synthesis of CNFs was carried out over self-dispersing nickel catalyst at 600 °C. The produced CNFs possess a well-defined segmented structure, high specific surface area (~300 m2/g) and high porosity (0.5-0.7 cm3/g). The addition of CH3CN into the reaction mixture allows the introduction of nitrogen into the CNF structure and increases the volume of mesopores. As a result, the capacity of CNF towards adsorption of 1,2-DCB from its aqueous solution increased from 0.41 to 0.57 cm3/g. Regardless of the presence of N, the CNF samples exhibited a degree of 1,2-DCB adsorption from water-organic emulsion exceeding 90%. The adsorption process was shown to be well described by the Dubinin-Astakhov equation. The regeneration of the used CNF adsorbent through liquid-phase hydrodechlorination was also investigated. For this purpose, Pd nanoparticles (1.5 wt%) were deposited on the CNF surface to form the adsorbent with catalytic function. The presence of palladium was found to have a slight effect on the adsorption capacity of CNF. Further regeneration of the adsorbent-catalyst via hydrodechlorination of adsorbed 1,2-DCB was completed within 1 h with 100% conversion. The repeated use of regenerated adsorbent-catalysts for purification of solutions after the first cycle of adsorption ensures almost complete removal of 1,2-DCB.

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.