Chemical Vapor Decomposition Research Articles

Upcycling Plastic Waste into Valuable Carbon Nanomaterials

AbstractThe global issue of plastic waste accumulation is now widely acknowledged as a significant environmental challenge that affects all aspects of life, economies, and natural ecosystems worldwide. Hence, it is crucial to develop sustainable solutions to traditional disposal methods. One promising solution involves upcycling plastic waste into valuable carbon nanomaterials such as carbon nanotubes, graphene, and carbon nanofibers, among others. This critical review provides an overview of the problems associated with plastics, including their various types and properties, as well as their significant impact on the environment and the methods currently employed for waste management. Furthermore, it delves into recent advancements in upcycling plastic waste into carbon nanomaterials through four state‐of‐the‐art methods with the potential for scaling up and enabling industrial applications: thermal decomposition, flash joule heating (FJH), chemical vapor decomposition (CVD), and stepwise conversion. For each method, highly influential and seminal papers were selected, and their research approaches and observed results were thoroughly analysed. This upcycling approach transforms plastic waste into valuable resources, promoting a waste‐to‐value concept that reduces environmental impact and supports the circular economy. By creating new materials from discarded plastics, it addresses waste management challenges while generating economic value.

Advanced Composite for sp3‐Carbon‐Based Gas Sensing Application from Gold Organometallic Single Nanolayering on Diamondoids

AbstractThe assembly of hybrid materials combining a pure sp3‐C platform from nano‐and microcrystals of molecularly‐defined nanometer‐sized functionalized diamondoids (nanodiamonds) coated with a gold transition metal nanolayer is conducted from the gas phase, following a two‐steps vapor phase dry construction process. By using first the controlled vapor phase self‐assembly of primary phosphine diamantane derivatives, followed by a chemical vapor decomposition of a suited gold organometallic complex the synthesis of the nanocomposite Au@H2P–DiamOH 2 is achieved. The gold deposit surface analysis reveals the formation of a Au–P covalent bonding, which excludes the formation of phosphine oxide, as confirmed at higher depth into the nanocomposite by Hard X‐ray Photoelectron Spectroscopy analysis (HaXPES). The thickness d of the gold layers deposited onto the surface of diamondoids is estimated to be around d = 0.8 ± 10% nm from XPS data, which allows combining the composite Au@H2P–DiamOH 2 with ITO interdigitated electrodes, to produce a long‐life, highly stable and reproducible, n‐type behavior sensor for ammonia detection. A relative response (RR) of 150% at 30 ppm and a limit of detection of 6 ppm are measured at room temperature (20 to 25 °C) and at 45% of relative humidity.

Interface engineering and impedance matching strategy to develop core@shell urchin-like NiO/Ni@carbon nanotubes nanocomposites for microwave absorption

It is well recognized that interfacial effect and/or impedance matching play a great impact on microwave absorption. Herein, we proposed a facile strategy to take full advantage of interface engineering and impedance matching for boosting microwave absorption performance (MAPs). Three-dimensional (3D) hierarchical urchin-like core@shell structured NiO/Ni@CNTs multicomponent nanocomposites (MCNCs) were elaborately constructed and produced in high efficiency through a facile continuous chemical bath deposition, thermal treatment, and catalytic chemical vapor decomposition process. By controlling the pyrolysis time, the NiO/Ni@CNTs urchin-like MCNCs with different lengths and aggregation degrees of CNTs could be selectively synthesized. The obtained results revealed that the enhanced CNT contents provided abundant interfaces and effectively aggrandized their interfacial effects, which resulted in improved polarization loss, conductivity loss, and comprehensive MAPs. Impressively, the interfaces and impedance matching in the designed NiO/Ni@CNTs urchin-like MCNCs could be optimized by regulating the pyrolysis temperature, which further improved the comprehensive MAPs. And the designed NiO/Ni@CNTs urchin-like MCNCs could simultaneously display strong absorption capabilities, broad absorption bandwidths, and thin matching thicknesses. Therefore, our findings not only provided a simple and universal approach to produce core@shell structured magnetic carbon-based urchin-like MCNCs but also presented an interface engineering and impedance matching strategy to develop the tunable, strong absorption, broadband, lightweight high-efficiency microwave absorbers.

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.

Temperature Dependence of Thermal Conductivity of Giant-Scale Supported Monolayer Graphene.

Past work has focused on the thermal properties of microscale/nanoscale suspended/supported graphene. However, for the thermal design of graphene-based devices, the thermal properties of giant-scale (~mm) graphene, which reflects the effect of grains, must also be investigated and are critical. In this work, the thermal conductivity variation with temperature of giant-scale chemical vapor decomposition (CVD) graphene supported by poly(methyl methacrylate) (PMMA) is characterized using the differential transient electrothermal technique (diff-TET). Compared to the commonly used optothermal Raman technique, diff-TET employs joule heating as the heating source, a situation under which the temperature difference between optical phonons and acoustic phonons is eased. The thermal conductivity of single-layer graphene (SLG) supported by PMMA was measured as 743 ± 167 W/(m·K) and 287 ± 63 W/(m·K) at 296 K and 125 K, respectively. As temperature decreased from 296 K to 275 K, the thermal conductivity of graphene was decreased by 36.5%, which can be partly explained by compressive strain buildup in graphene due to the thermal expansion mismatch.

In situ synthesis of highly stable FeCo alloy encapsulated in carbon from ethanol

– FeCo alloy nanoparticles encapsulated in carbon were synthesized in situ via chemical vapor decomposition using ethanol as carbon precursor at temperatures of 400, 500, 600 and 700 °C. The study was carried out in order to obtain a material with high chemical and thermal resistance. The materials were characterized by X-Ray Diffractometry (XRD), Magnetometry, Mössbauer Spectroscopy (ME), Raman Spectroscopy, Thermogravimetric Analysis (TGA), Temperature Programmed Reduction (TPR-H2), Temperature Programmed Desorption (TPD-NH3 and TPD-CO2), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Gas Chromatography (GC). The results indicated that an increase in the synthesis temperature directly influences the amount of carbon deposited on the alloy and, consequently, on its encapsulation. The increase in the synthesis temperature also provided chemical stability against pH variations between 3 and 11, greater resistance against oxidation, greater thermal stability, as well as an increase in the graphitization degree. SEM and TEM images confirmed the presence of carbon nanotubes whose organization is greater for the sample synthesized at higher temperature; the tip of nanotubes showed the encapsulated FeCo alloy nanoparticle. Methylene blue (MB) adsorption was performed as a model to evaluate the encapsulation degree for the alloy, which is favored at higher temperatures.

Comparison of carbon nanotube deposition on HfB2, ZrB2, and TiB2 by chemical vapor decomposition

CNTs were successfully synthesized on refractory metal diborides (HfB2, ZrB2, and TiB2) via CVD, with Ni as the catalyst at about 850–1200 °C. The obtained powders were densified via SPS at 1400–1700 °C to obtain a composite. The microstructures of the grown CNTs were characterized. The mechanical performances of the as-received materials were tested to evaluate the enhancing impact of CNTs grown in situ. Phase analysis of the final materials was conducted by XRD to eliminate the effects of impurities. The optimal strength and toughness, respectively, were 1013 ± 48 MPa and 10.7 ± 0.5 MPa·m1/2 for TiB2-Ni-CNT composites; 988 ± 47 MPa and 9.4 ± 0.4 MPa·m1/2 for ZrB2-Ni-CNT composites; and 912 ± 43 MPa and 8.5 ± 0.3 MPa·m1/2 for HfB2-Ni-CNT composites. The CNTs grown in the boride matrix exhibited uniform dispersion, resulting in further enhancement.

Studies on Compatibility of Sodium 4,5-Dicyano-2-(trifluoromethyl)Imidazolate Based Electrolytes with Novel Cathode Active Materials for Sodium-Ion Batteries

Sodium-ion batteries are promising alternative to lithium-ion batteries and a case of study of many researchers. Researches from Warsaw University of Technology are constantly working on modern electrolytes, including NaPDI and NaTDI, that are promising for application in Na-ion batteries due to the easy synthesis path [1]. Also the new methods of electrodes’ active materials synthesis is essential topic of researches. The modification of the conditions of synthesis using wet impregnation method and different way of introduction of Li+ into active material by using various precursors in synthesis leads to changes of properties of the electrodes [2]. A huge issue for Na-ion batteries is finding a suitable anode. A novel idea is using Microwave Plasma Chemical Vapour Decomposition of SbxOy/C to achieve stable anode [3].Presented research data is based on electrolytes containing imidazole salts and modern cathodes for Na-ion batteries. Due to the conducted measurement, the conductivity of the electrolytes containing NaTDI salt differ due to the used solvents in 0.75 M concentration solutions: 6.61 mS cm-1 in PC, 11.87 mS cm-1 in EC:DMC (1:1) and 15.56 mS cm-1 in EC:DME (1:1) [4]. The knowledge based on many years of experience in research on Li-ion batteries was essential for sodium analogues synthesis, which has promising properties. The optimization of the electrolytes compositions and adjustment of the cells work parameters with the new type of electrodes were a key issue during electrochemical tests. The presentation will be enriched by the determining parameters of the metallic sodium electrode. Also possible application of electrolytes and electrodes will be shown. Studies were funded by ENERGYTECH-1 project granted by Warsaw University of Technology under the program Excellence Initiative: Research University (ID-UB). [1] New Tailored Sodium Salts for Battery Applications, Anna Plewa-Marczewska, Tomasz Trzeciak, Anna Bitner, Leszek Niedzicki, Maciej Dranka, Grażyna Z. Żukowska, Marek Marcinek, and Władysław Wieczorek, Chem. Mater. 2014, 26, 17, 4908–4914[2] Different strategies of introduction of lithium ions into nickel-manganese-cobalt carbonate resulting in LiNi0.6Mn0.2Co0.2O2 (NMC622) cathode material for Li-ion batteries, Magdalena Zybert,, Hubert Ronduda, Anna Szczęsna, Tomasz Trzeciak, Andrzej Ostrowski,Elżbieta Żero, Władysław Wieczorek, Wioletta Rarog-Pilecka, Marek Marcinek, Solid State Ion. 2020, 348, 115273[3] Microwave Plasma Chemical Vapor Deposition of SbxOy/C negative electrodes and their compatibility with lithium and sodium Hückel salts—based, tailored electrolytes, A. Bitner-Michalska, K. Michalczewski, J. Zdunek, A.Ostrowski, G. Żukowska, T. Trzeciak, E. Żero, J. Syzdek M.Marcinek, Electrochim. Acta 2016, 210, 395-400[4] Liquid electrolytes containing new tailored salts for sodium-ion batteries, A. Bitner-Michalska, A. Krztoń-Maziopa, G. Żukowska, T. Trzeciak, W. Wieczorek, M. Marcinek , Electrochim. Acta 2016, 222, 108-115

Cu3Si enhanced crystallinity and dopamine derived nitrogen doping into carbon coated micron-sized Si/Cu3Si as anode material in lithium-ion batteries

A chemical vapor decomposition (CVD) enhanced carbon coated Si/Cu3Si composite aggregate (C-Si/Cu3Si@C) is prepared as anode material to alleviate volume expansion and improve the electrochemical performance for lithium-ion batteries (LIBs). In this work, micron-sized C-Si/Cu3Si@C is fabricated through self-assembling of dopamine as first carbon precursor on irregularly shaped and sub-micron-sized Si/Cu3Si composite, followed by CVD with ethylene (C2H4) as second carbon precursor. Besides, dopamine not only self-assembles on the surface of Si/Cu3Si composite but also grows into sheet-like film that supports and connects Si/Cu3Si composite into micron-sized aggregate. In addition to CVD, Cu3Si induces catalytic chemical vapor deposition (CCVD), which enhances integrality of the carbon shell as well as reinforce nitrogen doping into carbon shell to enhance conductivity. Therefore, the C-Si/Cu3Si@C composite performs in optimum condition when the cycle is stable, attaining delithiation capacity of 2101 mAh g−1, coulombic efficiency of 84.7% for the 1st cycle and achieves capacity retention of 82.9% after 100 cycles.

Development of multi-walled carbon nanotubes obtained from recycled plastics by single stage pyrolysis process

The development of nanofillers from plastic waste plays a significant role as an alternative plastic waste managing method. Multi-walled carbon nanotubes were produced by a single stage chemical vapor decomposition using polypropylene as carbon source in the presence of bimetallic catalyst. A mixture of Ar/H2 gas was used as a reducing agent for catalyst and at a later stage N2 was used to supply inert conditions for the pyrolysis product. Fe-Mn/Al2O3 catalyst was reduced at a temperature of 700 °C and PP waste was introduced at the same temperature to decompose at the surface of the catalyst to form the nanofillers. Tramission Electron Microscopy (TEM) and Raman characterization techniques were used to determine the properties of the nanofillers. The results showed that the developed nanofillers have a maximum diameter of 19.09 nm. TEM micrographs displayed lattice fringes at the magnitude of 20 nm indicating that the morphology of these nanofillers is crystalline. The Raman spectra showed the defect mode, D at the frequency of 1346 cm−1 and the tangential mode, G is at the frequency of 1588 cm−1. The intensity ratio ID/IG is 0,84 and signifies the quality of the nanofillers, as the ratio is the direct measure of the sample purity.The diameter obtained from the TEM analysis and the absence of the Radial Breathing Mode (RBM) on Raman spectra concluded that the nanofillers produced can be classified as Multi-Walled Carbon Nanotubes (MWCNT).

Synthesizing of helical-single walled carbon nanotubes by chemical vapour decomposition for engine

The captivating interest on carbon nanotubes (CNTs) has kindled the research activity after its discovery in 1991. It is due to its fabulous properties which have opened numerous applications like high weight to strength ratio, field emission transistors, and catalysis. Irrespective of the stunning technological development there is still much struggle in the synthesis aspect, which is a great drawback in compliance of these unique materials in the commercial application. Apart from various known method catalytic chemical vapor deposition (CCVD) is more advantages, where SWCNTs can be produced with varying diameters, large scale production, with high purity, variable temperature and most importantly it can be produced economically. In CCVD technique, We have used magnesium metal as a substrate with transition metal like Fe, and Ni, to prepare combustion catalyst. SWCNTs synthesized from FeaNibMg1-(a + b)O (FNM) catalyst had a higher yield than other catalysts with helical structure in the single layer of graphitic carbon (h-SWCNTs). The morphology of the synthesized h-SWCNTs was identified by Field Emission Scanning Electron Microscope and many others. Environmental damage from industries is looking for a prominent candidate to sort out the issues such as high catalytic activity, reusability, and stability norms. With the obtained result a comparative study was done against combustion catalyst, purified and pristine SWCNTs. It is found that the pristine h-SWCNTs had a good photo catalytic activity with this result we have confirmed SWCNTs synthesized from solution combustion technique can be utilized for commercial application.

Robust Design of Silicon/Graphite Composite Via Atomic-Scale Rearrangement for High Performance Lithium Ion Batteries

State-of-the-art lithium-ion battery (LIB) technology are still challenged with many other requirements, including high-energy density, long cycle life, safety and cost by the increasing demand of the electric vehicle energy-storage market. Moreover, key to success for commercialization of EVs is reducing the charging time of the batteries. In general, the conventional graphite has shown not only low electrochemical performance but also safety problems arisen from the metallic lithium plating at the surface of the anode electrode at the high current density (4mA/cm2) due to a sluggish kinetics during intercalation reaction and working voltage potential neighboring almost 0V (versus Li/Li+). Alternatively, among the alloy-type anodes, silicon is considered as promising anode material due to the high gravimetric capacity of 3572 mAh g-1 and proper lithium-alloying potential (0.22 V vs. Li/Li+) to prevent unwanted lithium plating. However, to the best of our knowledge, the majority of previously reported Si anodes do not demonstrate the rate capabilities at high electrode density (g/cc) due to the large volume changes (>300%) and low electrical conductivity of Si anodes. Herein, we have proposed a composite consisting of a nanoscale silicon coating layer on graphite/carbon nanofibers through nickel-catalyzed-CNF growth on the graphite by chemical vapor decomposition (CVD) using both ethylene (C2H4) and silane (SiH4) gas. The chemical Si-C bonding by atomic rearrangement of CNF and a-Si layer prevents the exfoliation of the active Si layer from the surface of CNF during cycles. For practical viability, all electrochemical tests were performed in the full-cell as well as in the half-cell configurations with high energy density (> 1.6g cc-1), high areal capacity (3.3 mAh cm2) and limited binder composition (< 4wt %). As a result, by increasing electrical conductivity of silicon/graphite composite and existing high stability of ultrathin Si layer, our composite shows remarkable improvement in electrochemical performances even at high current density with those of the conventional graphite.

Structural characterization of interaction between SWCNTs and 6-phenyl-2-thiouracil by molecular spectroscopic methods

Chemical vapor decomposition (CVD) method is used to synthesize single wall carbon nanotubes (SWCNTs), after purification process COOH functional group modified SWCNTs are obtained via oxidation reaction by using H2SO4/HNO3. 6-Phenyl-2-thiouracil (6P2T) molecule is bonded on the surface of functionalized SWCNTs. Raman spectroscopy was used to characterize bands of SWCNTs and differences among raw SWCNT, functionalized SWCNTs and 6P2T bonded SWCNTs are shown. FT-IR spectra have been used to determine vibrations of SWCNTs and the interaction sites between SWCNTs and 6P2T molecule. XRD and EDX methods indicate removing catalyst materials and amorphous carbon during the purification process.

Magnetic Nanoparticles for Photocatalytic Ozonation of Organic Pollutants

Magnetic nanoparticles (MNP) composed of iron oxide (or other metal–FeO cores) coated with carbon produced by chemical vapour decomposition (CVD) were used in the photocatalytic ozonation of oxamic acid (OMA) which we selected as a model pollutant. The incorporation of Ag and Cu on FeO enhanced the efficiency of the process. The carbon phase significantly increased the photocatalytic activity towards the conversion of OMA. As for the synthesis process, raising the temperature of CVD improved the performance of the produced photocatalysts. The obtained results suggested that the carbon phase is directly related to high catalytic activity. The most active photocatalyst (C@FeO_CVD850) was used in the removal of other compounds (dyes, industrial pollutants and herbicides) from water and high mineralization levels were attained. This material was also revealed to be stable during reutilisation.

Electromagnetic property of the Ni@mica sheet fabricated by chemical vapor decomposition method

The hybrid particle of Ni coated on the mica was fabricated based on the Ni(CO)4 gas decomposition. The hybrid particle structure and morphology were analyzed by the scanning electron microscopy. The crystal grain structure was characterized in X-ray diffraction (XRD) patterns. The static magnetic parameters were tested using the vibrating sample magnetometer. The complex permittivity and permeability were measured by a vector network analyzer in 2–18 GHz, and then the reflection loss (RL) was simulated as the absorber thickness was set. The morphology results indicated that the uniform Ni film existed at the mica surface and the XRD pattern showed that the Ni phase was (1 1 1). The dielectric loss and magnetic loss characteristics existed according to the complex permittivity and permeability. The dielectric loss was caused by several polarization types on the basis of Debye equation, while the magnetic loss was mainly due to the eddy current effect. As the weight fraction of Ni@mica increased, the permittivity and permeability increased, as well as the attenuation constant and impedance matching ratio. The composite with 50% Ni@mica which had the better absorption property and the minimum RL was − 14.5 dB at 18 GHz with thickness 6 mm.

A Novel Si/C Composite as a High Capacity Anode Material for Lithium-ion Batteries

Silicon based electrode materials for Li-ion battery have attracted great attention due to the high theoretical capacity of 4212 mAh/g (3.75 moles of Li per mole of Si) compared to graphite (1 mol Li per 6 mol C) used in commercial LIBs. Unfortunately, practical applications of silicon as an anode material exhibit the huge volume change (>300%) during the alloying / dealloying process with Li, which would result in the loss of electrical conductivity, dramatic pulverization of silicon, and consequently a rapid capacity fading in the cycling. To alleviate this problem, silicon nanosized or nanostructures materials have been suggested, which can increase the transport of electron and lithium ion and reduce mechanical stress during cycling, resulting in improved electrochemical performance. Among these nanostructures, the combination with carbon is becoming attractive and important material because it improves the electric conductivity and plays a role of a buffer of volume expansion. In this research, a novel composite electrode material consisting of nanocrystalline silicon and porous graphite has been developed as an anode candidate for LIB. Nanocrystalline silicon was coated onto porous graphite via chemical vapor decomposition of SiH4 gas and subsequently pitch coating was carried out, which is known for a good method for preventing the natural oxidation of silicon layer and improving capacity. We analyzed electrochemical properties of blended anode with graphite and nanocrystalline silicon­-porous graphite composite material. The capacity retention of the blending anode for nanocrystalline silicon­-porous graphite is 96% after 50 cycles with high coulombic efficiency of 90.1%, which is improved electrochemical performance compared with silicon non-porous graphite composite anode. Especially, the nanocrystalline silicon­-porous graphite composite material has lower expansion of electrode, comparing with silicon non-porous graphite composite material. The expansion of the nanocrystalline silicon­-porous graphite composite electrode is 42% after 1 cycle, while the expansion of the silicon non-porous graphite composite is 62% after 1 cycle. These improvements are attributed to the porous carbon shell, which reduces the cell expansion, prevents rupture of electrical path, stabilize the cycle performance.

Adsorption of Trace Phosphine in Circular Hydrogen of a Polysilicon Chemical Vapor Deposition Stove by Cu/γ-Al2O3

In our previous studies, CuCl2 showed excellent removal efficiency for trace phosphine in circular hydrogen of a polysilicon chemical vapor decomposition (CVD) stove. In this study, the investigati...

Co/C/Fe/C hierarchical flowers with strawberry-like surface as surface plasmon for enhanced permittivity, permeability, and microwave absorption properties

Co/C/Fe/C core–shell hierarchical flowers (CSHFs) with various compositions and surface morphologies were fabricated by hydrothermal–chemical vapor decomposition. Surface-dependent electromagnetic properties were investigated at 2–18 GHz. Due to the localized surface plasmon resonance and coupling, Co/C/Fe/C CSHFs with strawberry-like surface exhibit significantly enhanced permittivity, permeability, exchange resonances, and attenuation compared with Co HFs and Co/C/Fe/C CSHFs with compact particle film. Such performances enable Co/C/Fe/C CSHFs to become excellent absorbers with strong absorption, broad bandwidth, and light weight. This finding demonstrates that the surface and interface designs of plasmonic heterostructures are critical to improve microwave absorption properties for future application.

A Novel Approach to the Layer-Number-Controlled and Grain-Size-Controlled Growth of High Quality Graphene for Nanoelectronics

Thermal chemical vapor decomposition of methane on copper is the most widely employed technique for high quality and large area graphene growth. Graphene growth by this technique tends to be limited to a monolayer owing to the surface mediated self-limiting growth mechanism, and hence, it is difficult to obtain continuous bilayers and multilayers. We report the layer-controlled growth of high quality and large area polycrystalline graphene on copper foil in a hot filament chemical vapor deposition (HFCVD) reactor and demonstrate that graphene can be grown with a controlled grain size in the range of 5–16 μm. The field effect hole mobilities of the largest grain monolayer and bilayer graphene and the thickest few-layer graphene are 4310 ± 348, 2745 ± 276, and 2472 ± 185 cm2V–1s–1, respectively, which are comparable to that of high quality polycrystalline graphene and suitable for future nanoelectronics. The results of the systematic parametric study hereby presented indicate that graphene adlayers grow on ...

Catalysts on Formation of Carbon-Encapsulated Iron Nanoparticles from Kraft Lignin.

Effects of physical and chemical states of iron-based catalysts on the formation of carbon-encapsulated iron nanoparticles (CEINs) synthesized thermally from kraft lignin were investigated. Experimental results indicated that if solution-based iron nitrate (FeN) was used as an iron source for the catalyst, CEINs observed were α-Fe and γ-Fe-based cores encapsulated by few layers graphitic-carbon (mostly 1–5 layers) and the majority of these CEINs were embedded in amorphous carbon matrix. The formation of graphitic-carbon shells is believed based on the dissolution and precipitation mechanism of amorphous carbon acting as the carbon source. If solid-based iron nanoparticles (FePs) were used as the catalyst, CEINs observed were α-Fe, γ-Fe, and Fe3C-based cores encapsulated with tangled graphitic-carbon nanoribbons and carbon tubules and the majority of these CEINs were found along the edge of amorphous carbon matrix. The growth of tangled graphitic-carbon nanoribbons and carbon tubules is based on a chemical vapor decomposition process, i.e., the carbonaceous gases from kraft lignin decomposition served as the carbon source.