Production Of Carbon Nanotubes Research Articles

Transforming CO2 into advanced 3D printed carbon nanocomposites

The conversion of CO2 emissions into valuable 3D printed carbon-based materials offers a transformative strategy for climate mitigation and resource utilization. Here, we 3D print carbon nanocomposites from CO2 using an integrated system that electrochemically converts CO2 into CO, followed by a thermocatalytic process that synthesizes carbon nanotubes (CNTs) which are then 3D printed into high-density carbon nanocomposites. A 200 cm2 electrolyzer stack is integrated with a thermochemical reactor for more than 45 h of operation, cumulatively synthesizing 37 grams of CNTs from CO2. A techno-economic analysis indicates a 90% cost reduction in CNT production on an industrial scale compared to current benchmarks, underscoring the commercial viability of the system. A 3D printing process is developed that achieves a high nanocomposite CNT concentration (38 wt%) while enhancing composite structural attributes via CNT alignment. With the rapidly rising demand for carbon nanocomposites, this CO2-to-nanocomposite process can make a substantial impact on global carbon emission reduction efforts.

Hydrogen and carbon nanotube production from microwave-assisted catalytic decomposition of plastic waste

Plastic waste has become an alternative resource for generating carbon-free hydrogen and valuable carbon. The challenge lies in the efficient catalytic pyrolysis of plastics, the energy-intensive nature of decomposition, and reactor configuration. In a single-stage process, the presence of solid plastic with the catalyst leads to carbon block formation, inhibiting the growth of filamentous structure. We proposed a two-stage process incorporating microwave-assisted heating, encompassing thermal pyrolysis at 500 ˚C, followed by catalytic chemical vapor deposition at 800 ˚C. Transition metals, including iron, nickel, and cobalt, and their alloys were examined for catalytic performance along with assessments of catalyst-to-feed mixing ratios and catalyst stability. Comprehensive characterization techniques were employed to explore nanocrystal size, dispersion, reduction behavior, and support interaction strength. The FeNi/Al2O3 catalyst exhibited the highest yields among the selected catalysts, attributed to its optimized nanocrystalline size and interaction strength. These characteristics facilitated the production of 445 mg/gplastic of carbon nanotubes and 52.1 mmol/gplastic of hydrogen during low-density polyethylene decomposition, corresponding to the extraction of 52 % carbon and 72 % hydrogen relative to theoretical content. The catalyst exhibited a sustained efficiency over ten consecutive cycles, yielding 513 mg/gplastic of highly crystalline multiwall carbon nanotubes, with electrification demonstrating promise for sustainably converting plastic waste into carbon-free hydrogen and carbon.

Production of carbon nanotubes as composite material modifiers using nanotechnology

Modern trends in composite materials science are associated with nanotubes having a carbon framework structure. The aim of this article is to develop and produce new composite materials using nanoparticles with increased characteristics, including radiation absorption with the possibility of their use in design schemes of various kinds of industry. The structure of nanotubes is determined by synthesis methods. Moreover, the CNTs characteristics are determined by the methods of transmission microscopy. In particular, the analysis of the profile of the X-ray spectral lines was carried out using a mixed Gaussian-Lorentzian distribution function. The multilayer CNTs were obtained by the method of catalytic decomposition of propylene. As a result, the improvement of physical and mechanical characteristics by 30–40% is achieved. Thus, the efficiency of introducing carbon nanotubes into the polymer matrix to improve the physicochemical, physical-mechanical, and operational characteristics of composite nano-polymer materials is proved. Finally, it is shown that functionalized carbon-containing nanoparticles could be used as modifiers to regulate the process of curing and elastification of epoxy substances when creating polymer composite materials for structural purposes.

Stoichiometric-Ratio-Controlled Fe and Ni Non-noble Metal Catalysts Supported on γ-Al2O3 for Turquoise Hydrogen and Carbon Nanotubes Production.

Herein, we synthesized a series of catalysts comprising iron (Fe), and nickel (Ni) supported on γ-Al2O3 nanopowder (Fe-Ni/γ-Al2O3) by controlling the stoichiometric ratio of the metals through the facile co-precipitation method. The ratio of Fe and Ni on the γ-Al2O3 support varied from 0 to 70 weight percent (wt%). The freshly prepared catalysts' phase, structure, and crystallinity exhibited variability as the Fe and Ni stoichiometric ratios were altered. The catalyst demonstrated effective performance in methane cracking, producing turquoise hydrogen and carbon nanotubes (CNTs) using a temperature-programmed reactor coupled with mass spectrometry. It was observed that the Fe3Ni4 catalyst, comprising 30% Fe and 40% Ni, exhibited a maximum methane conversion rate of 85% and a hydrogen yield of 72.55%. Moreover, the values of turnover frequency (2.38 min-1) indicated that the Fe3Ni4 had a better production rate and was consistent with the conversion process throughout the reaction. The structural attributes of the spent catalysts were examined, revealing variations in the lateral length, uniformity, and diameters (~33 to 56 nm) of the produced Carbon Nanotubes (CNTs) when transitioning from catalyst Fe0Ni7 to Fe7Ni0. The investigation underscored the significance of metal stoichiometrically controlled catalysts and their catalytic efficacy in methane cracking applications.

A Cycloparaphenylene Acetylene as Potential Precursor for an Armchair Carbon Nanotube.

The bottom-up synthesis of carbon nanotubes (CNTs) is a long-standing goal in synthetic chemistry. Producing CNTs with defined lengths and diameters would render these materials and thus their fascinating properties accessible in a controlled way. Inspired by a recently reported synthesis of armchair graphene sheets that relied on a benzannulation and Scholl oxidation of a poly(p-phenylene ethynylene), the same strategy is applied on a cyclic substrate with a short, but well defined CNT as target structure. Herein we report the synthesis of a derivatized [12]cycloparaphenylene acetylene ([12]CPPA) that was accessible employing a Sonogashira macrocyclization. The obtained macrocycle is the largest [n]CPPA reported to date and displays bright turquoise fluorescence with a large quantum yield of 77 %. The [12]CPPA can be transformed by a 12-fold benzannulation that converts each alkyne to a naphthalene and therefore allows formation of an armchair [12,12]CNT precursor. The final 72-fold Scholl oxidation to the [12,12]CNT turned out to be challenging and its optimization requires an improved synthetic strategy to produce large quantities of the final precursor. The developed approach poses a potential break through strategy for the production of CNTs and certainly incentivizes synthetic chemists to apply the same methodology for various conjugated macrocycles.

MCM-41 from rice husk silica as a support for Ni catalyst in the emission-free production of H2 by CH4 cracking.

Selecting a sustainable source of silica from biomass waste was the research challenge that was put forth in this investigation. Herein, the MCM-41 support has been synthesized using a renewable rice husk and explored as a support for Ni-Cu catalyst in the production of zero-emission H2 through CH4 pyrolysis. The role of Cu promoter was investigated by doping different amounts of Cu loading to 30wt%Ni/R-MCM-41catalyst, which improved the catalytic performance in terms of CH4 conversion and stability. An optimum Cu loading of 3wt% addition to 30wt%Ni/R-MCM-41 catalyst demonstrated the best catalytic performance compared to all the catalysts in terms of hydrogen yield (15,218mol H2/mol Ni) and carbon formation rate. The Ni-Cu alloy formation was confirmed by X-ray diffraction, H2-temperature programmed reduction, and pulse chemisorption studies, as demonstrated by decreased H2 uptake (from 41 to 33μmol/gcat) and enhanced N2O (from 89.2 to 138.3μmol/g) uptakes, which results in a significant improvement in the availability of the surface metal species (both Cu and Ni), which in turn contributed to increase the CH4 cracking performance and stabilization of Ni species. Additionally, doping Cu results in better carbon nanotube production, as shown by the lowest ID/IG ratio from the Raman spectroscopic analysis.

MgOMo2C/multiwalled carbon nanotube composite for high-performance supercapacitor applications

Magnesium molybdate (MgMoO4) nanostructure has been successfully prepared and employed as a catalyst for the production of multi-walled carbon nanotubes (CNTs) by the chemical vapor deposition method. The prepared nanostructure materials are characterized through XRD, TEM, FTIR, BET and Raman spectroscopy. The XRD results and TEM images confirm the formation of the plate-like MgMoO4 structure, as well as the existence of Mo2C and CNTs in the type of bundles structure (CNTBs). The high dispersion and stability of Mo nanoparticles in the composite of plate-like MgMoO4 is responsible for the formation of CNTBs with uniform diameters. Thus, the plate-like MgMoO4 nanoparticles and the MgOMo2C@CNTBs hybrid material are assessed as electrodes in a supercapacitor device for the first time. The produced hybrid supercapacitor MgOMo2C@CNTBs has a good specific capacitance (354 F g−1) and strong cycling stability (82 percent capacity retention over 2000 cycles)

Physical properties of industrially produced carbon nanotube yarns for use in structural nanocomposites

Industrially-produced carbon nanotube (CNT) networks are a promising base for high-performance, continuous CNT nanocomposites, motivating widespread use in research and application development. Floating catalyst chemical vapor deposition (FCCVD) is a scalable, widely-adopted approach for synthesis of CNT networks; however, FCCVD can yield networks with organic impurities which complicate their characterization and processing. Herein, we analyze two varieties of FCCVD-synthesized commercial CNT yarn to explore the effects of densification and purification as they relate to forming infiltrated polymer composites. First, the fluid permeabilities and porosities of neat roving and chemically-stretched CNT yarns (CSYs) are estimated and compared to gas adsorption studies, which suggest high-tenacity CSYs are largely impermeable, leading to dry-core composites when polymer infiltration is attempted. Next, the presence and effects of oxygen-rich amorphous carbon impurities in the CSYs are identified and found to exist at the scale of CNT bundles, wherein the amorphous carbon behaves like a hygroscopic polymer matrix in a composite. Removal of the amorphous carbon phase in a 130%-increase in specific surface area, as quantified by BET analysis, and a statistically significant reduction in tensile properties. We discuss challenges in estimating yarn alignment and crystallinity resulting from these factors, and place our results in context of past studies analyzing intrinsic organic coatings in FCCVD-synthesized CNT networks.

Effect of Temperature on the Growth Rate of Carbon Nanotubes (CNTs) using Electrodeposition Method

Electrodeposition is one of the carbon capture methods used to produce carbon nanotubes with temperature as one of the variable. The research aims to analyze the effect of temperature on the growth rate of carbon nanotubes of 723oC, 750oC, 800oC, 850oC and 900oC using X-Ray Diffraction (XRD) testing. Analyzing deposit morphology at the same temperature using Scanning Electron Microscope (SEM) testing. The results of research show that the most optimal growth rate for carbon nanotubes occurred at 750oC of 7,949 g cm-2 hours-1. At a temperature of 750oC, carbon deposits are easier than at 723oC because that’s the melting point of lithium carbonate and has not completely decomposed. The XRD test show that at 750oC is the highest peak at 2θ= 26.21o. The SEM test show that the optimal morphological structure formed occurs at a temperature variation of 750oC with a fibrous morphology and little impurity at the ends. The results of the CNT percentage using the Material Analysis Using Diffraction (MAUD) method show that the largest quantitative value of the CNT percentage occurs at a temperature of 800oC of 4.08%.

Cellular uptake of multi-walled carbon nanotubes is associated to genotoxic and teratogenic effects towards the freshwater diatom Nitzschia linearis

The increase in industrial production of multi-walled carbon nanotubes (MWCNTs) raises concerns about their potential adverse effects associated to environmental releases, especially in aquatic environments where they are likely to accumulate. This study focuses on the environmental impact of MWCNTs, specifically on a benthic freshwater diatom (Nitzschia linearis), which plays a major role in the primary production of water bodies. The obtained results indicate that exposure to MWCNTs in the presence of natural organic matter (NOM) inhibits diatom's growth in a dose-dependent manner after 72 h of exposure. Interestingly, the photosystem II quantum yield (PSIIQY) in diatoms remains unaffected even after exposure to MWCNTs at 10 mg/L. After 48 h of exposure, MWCNTs are found to bind preferentially to extracellular polymeric substances (EPS) produced by diatoms, which could decrease their toxicity by limiting their interaction with this organism. However, measurement of genotoxicity and teratogenicity in diatoms exposed to MWCNTs revealed that the exposure to MWCNTs increased the occurrence of cells with micronuclei and abnormal frustules. Microscopy analyses including two-photon excitation microscopy (TPEM) revealed the internalization of MWCNTs. Investigations of the diatom's frustule structure using Scanning electron microscopy (SEM) indicated that the presence of pore structures constitutes a pathway allowing MWCNTs uptake. The presence in the diatom's cytoplasm of MWCNTs might possibly induce disturbances of the cellular components, leading to the observed genotoxic and teratogenic effects. In view of previous studies, this work underscores the need for further studies on the interaction between nanomaterials and different diatom species, given the species-specific nature of the interactions.

Drastic enhancement by in situ CNTs growth of carbon felt activity toward the electrodegradation of an azo dye

A new composite material has been developed for the electro-Fenton process to remove Acid Orange 7 (AO7), an azo dye pollutant, from wastewater. This material features the in situ growth of carbon nanotubes (CNT) at the interface of carbon felt/phenolic resin (CF/PR). Different CF/PR composite materials were manufactured by impregnation of an alcoholic phenolic resin/ferrocene solution on a carbon felt that was treated by acidic oxidation or not. The carbonization step under N2 atmosphere is necessary for the growth of the CNTs at the interface of the CF/PR composite. SEM observations show clearly the presence of CNTs at different levels of growth at the interface CF/PR. They also reveal that oxidizing carbon felts greatly boosts the CNT production in the composite (CF-oxy/CNT/PR). Raman spectroscopy, using the ID/IG ratio, confirmed these findings, matching the conductivity measurements. The formation of CNT via a ferrocene catalyst at the CF/PR interface notably enhanced the composite electrode's conductivity, especially when the carbon felts were oxidized. The elaborated composites were further used as cathodes to carry out the electro-Fenton (EF) process applied to the degradation of Acid Orange 7 (AO7) in the treated effluent. The discoloration of the AO7 solution was achieved in <15 min, demonstrating an effective treatment. In addition, the progress of AO7 mineralization was tracked through measurements of total organic carbon (TOC). Therefore, after 4 h of electro-Fenton treatment, a significant enhancement was evidenced with nearly a complete mineralization of 98 % compared to only 55 % achieved with the raw carbon felt (CF) material as electrode. As a result, the proposed method of modifying the CF/PR composite interface through CNT growth has improved their electrocatalytic activities, showcasing their promising potential for electrochemical applications.

Preparation of high quality carbon nanotubes by catalytic pyrolysis of waste plastics using FeNi-based catalyst

Plastic waste pollution is the serious environmental problem, and catalytic pyrolysis of waste plastics is an effective way to solve this problem. Carbon nanotubes (CNTs) are prepared by catalytic pyrolysis of low-density polyethylene (LDPE) waste plastics by one-stage method using iron nitrate and nickel nitrate as catalyst. The growth mechanism of CNTs is analyzed in detail. TPO, XRD, SEM and Raman analyses show that increasing Ni content contributes to the production of CNTs with good morphology and high graphitization degree. While the increasing Fe content contributes to improving the yield of CNTs. The outer and inner diameters of the FeNi12-CNTs-800 are about 21 nm and 8 nm with the length of 18.9 μm, respectively. LDPE pyrolysis gases are analyzed to determine that the primary carbon source required for CNTs growth is C2H4. The C2H4 adsorption and decomposition processes on FeNi alloys are performed to reveal the growth mechanism of CNTs, based on density functional theory calculation. Three kinds of the growth models are proposed to explain the difference of the CNTs tubular shape. FeNi12-CNTs-800 are used to remove microplastics from wastewater due to existence of magnetic. PVC can be quickly removed from wastewater with removal of 100 % at 20 min. This study provides an effective way for recycling and treatment of waste plastic.

Mo-Doped Ni/C Catalyst for Improved Simultaneous Production of Hydrogen and Carbon Nanotubes through Ethanol Decomposition.

A Mo-Ni/C catalyst was developed and assessed in terms of the decomposition of ethanol to produce multi-wall carbon nanotubes (MWCNTs) and hydrogen. The catalyst utilized different molar ratios of Mo:Ni (1:9, 2:8, and 3:7), with Mo acting as a dopant to enhance the MWCNT yield and Ni acting as the primary active phase for MWCNT formation. Among the tested ratios, the 2:8 Mo:Ni ratio exhibited the optimal performance, yielding 86% hydrogen and high-quality MWCNTs. In addition to hydrogen, the process also generated CO, CH4, and CO2. Gas chromatography (GC) was employed to analyze the influence of the Mo:Ni ratio on gas production and selectivity, while the quality of the resulting MWCNTs was evaluated using SEM, Raman spectroscopy, and TEM analyses.

Simultaneous production of syngas and carbon nanotubes from CO2/CH4 mixture over high-performance NiMo/MgO catalyst

Direct conversion of biogas via the integrative process of dry reforming of methane (DRM) and catalytic methane decomposition (CDM) has received a great attention as a promising green catalytic process for simultaneous production of syngas and carbon nanotubes (CNTs). In this work, the effects of reaction temperature of 700–1100 °C and CH4/CO2 ratio of biogas were investigated over NiMo/MgO catalyst in a fixed bed reactor under industrial feed condition of pure biogas. The reaction at 700 °C showed a rapid catalyst deactivation within 3 h due to the formation of amorphous carbon on catalyst surface. At higher temperature of 800–900 °C, the catalyst can perform the excellent performance for producing syngas and carbon nanotubes. Interestingly, the smallest diameter and the highest graphitization of CNTs was obtained at high temperature of 1000 °C, while elevating temperature to 1100 °C leads to agglomeration of Ni particles, resulting in a larger size of CNTs. The reaction temperature exhibits optimum at 800 °C, providing the highest CNTs yield with high graphitization, high syngas purity up to 90.04% with H2/CO ratio of 1.1, and high biogas conversion (XCH4 = 86.44%, XCO2 = 95.62%) with stable performance over 3 h. The typical composition biogas (CH4/CO2 = 1.5) is favorable for the integration process, while the CO2 rich biogas caused a larger grain size of catalyst and a formation of molybdenum oxide nanorods (MoO3). The long-term stability of NiMo/MgO catalyst at 800 °C showed a stable trend (> 20 h). The experimental findings confirm that NiMo/MgO can perform the excellent activity and high stability at the optimum condition, allowing the process to be more promising for practical applications.

Artificial neural network for predicting the performance of waste polypropylene plastic-derived carbon nanotubes

AbstractIn this study, an artificial neural network model using function fitting neural networks was developed to describe the yield and quality of multi-walled carbon nanotubes deposited over NiMo/CaTiO3 catalyst using waste polypropylene plastics as cheap hydrocarbon feedstock using a single-stage chemical vapour deposition technique. The experimental dataset was developed using a user-specific design with four numeric factors (input variable): synthesis temperature, furnace heating rate, residence time, and carrier gas (nitrogen) flow rate to control the performance (yield and quality) of produced carbon nanotubes. Levenberg–Marquardt algorithm was utilized in training, validating, and testing the experimental dataset. The predicted model gave a considerable correlation coefficient (R) value close to 1. The presented model would be of remarkable benefit to successfully describe and predict the performance of polypropylene-derived carbon nanotubes and show how the predictive variables could affect the response variables (quality and yield) of carbon nanotubes.

Enhanced synthesis of sponge-type multiwalled carbon nanotubes using SiO2-Fe2O3 catalysts via aerosol-assisted chemical vapor deposition: Electrochemical and absorption capacity studies

Carbon nanotube sponges synthesized at the laboratory scale typically use a Fe-based organometallic catalyst, but low-cost alternatives with a higher yield ratio are needed for large-scale production. This work introduces a catalyst made from a mixture of silicon dioxide (SiO2) and hematite (Fe2O3) as an innovative alternative for the high-yield production of spongy-type multi-walled carbon nanotubes (ST-MWCNTs). We used a ball-milled mixture of SiO2 and Fe2O3 powders as the catalyst and toluene and N, N-dimethylformamide as carbon and nitrogen sources in an aerosol-assisted catalytic chemical vapor deposition system. Incorporating SiO2 into the Fe-based catalyst increased production yield to 184 % of the catalyst weight. The synthesized ST-MWCNTs exhibited a high crystallinity ratio (ID/IG = 0.34) with a unique entangled bundle-type nanotube configuration. At the same time, the presence of Si atoms and oxygen-type functionalities, demonstrated by X-ray photoelectron spectroscopy, modified their electrochemical behavior, making them suitable for supercapacitor or sensor applications. Additionally, the spongy structure demonstrated a reversible absorption capacity of over 15 times its weight with organic solvents like gasoline or ethylene glycol. This new catalyst configuration opens alternatives for generating higher amounts of 3D carbon nanomaterials with potential energy storage, water filtration, and environmental remediation applications.

Converting Carbon Dioxide into Carbon Nanotubes by Reacting with Ethane

AbstractThe urgency to mitigate environmental impacts from anthropogenic CO2 emissions has propelled extensive research efforts on CO2 reduction. The current work reports a novel approach involving transforming CO2 and ethane into carbon nanotubes (CNTs) using earth‐abundant metals (Fe, Co, Ni) at 750 °C. This route facilitates long‐term carbon storage via generating high‐value CNTs and produces valuable syngas with adjustable H2/CO ratios as byproducts. Without CO2, direct pyrolysis of ethane undergoes rapid deactivation. The participation of CO2 not only enhances the durability of the catalyst, but also contributes about 30 % of the CNTs production, presenting a viable solution to CO2 challenges. The CNT morphology depends on the catalyst used. Co‐ and Ni‐based catalysts produce CNT with a 20 nm diameter and micrometer length, whereas Fe‐based catalysts yield bamboo‐like structures. This work represents a pioneering effort in utilizing CO2 and ethane for CNT production with potential environmental and economic benefits.

Converting Carbon Dioxide into Carbon Nanotubes by Reacting with Ethane.

The urgency to mitigate environmental impacts from anthropogenic CO2 emissions has propelled extensive research efforts on CO2 reduction. The current work reports a novel approach involving transforming CO2 and ethane into carbon nanotubes (CNTs) using earth-abundant metals (Fe, Co, Ni) at 750 °C. This route facilitates long-term carbon storage via generating high-value CNTs and produces valuable syngas with adjustable H2/CO ratios as byproducts. Without CO2, direct pyrolysis of ethane undergoes rapid deactivation. The participation of CO2 not only enhances the durability of the catalyst, but also contributes about 30 % of the CNTs production, presenting a viable solution to CO2 challenges. The CNT morphology depends on the catalyst used. Co- and Ni-based catalysts produce CNT with a 20 nm diameter and micrometer length, whereas Fe-based catalysts yield bamboo-like structures. This work represents a pioneering effort in utilizing CO2 and ethane for CNT production with potential environmental and economic benefits.

Analysis of Carbon Materials with Infrared Photoacoustic Spectroscopy.

Measurement of infrared spectroscopy has emerged as a significant challenge for carbon materials due to the sampling problem. To overcome this issue, in this work, we performed measurements of IR spectra for carbon materials including C60, C70, diamond powders, graphene, and carbon nanotubes (CNTs) using the photoacoustic spectroscopy (PAS) technique; for comparison, the vibrational patterns of these materials were also studied with a conventional transmission method, diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, or Raman spectroscopy. We found that the IR photoacoustic spectroscopy (IR-PAS) scheme worked successfully for these carbon materials, offering advantages in sampling. Interestingly, the profiles of IR-PAS spectra for graphene and CNTs exhibit negative bands using carbon black as the reference; the negative spectral information may provide valuable knowledge about the storage energy, production, structure, defect, or impurity of graphene and CNTs. Thus, this approach may open a new avenue for analyzing carbon materials.

Upcycling heteroatoms-containing plastics via bimetallic synergistic catalysis: Unveiling the role of O and Cl in C-H bond cleavage

Given the complicated compositions and hazards of heteroatoms-containing plastics, the efficient upcycling remains a huge challenge. Herein this work proposed an innovative route via dual-stage pyrolysis-catalysis platform to upcycle heteroatoms-containing plastics for high-purity H2 and carbon nanotubes (CNTs) production. Among HY-supported metallic catalysts, bimetallic Fe-Co/HY achieved the maximum H2 yield (41.25 mmol/gplastic) and selectivity (71.76 vol%), alongside the carbon production of 520 mg/gplastic, revealing a catalytically synergistic effect between Fe and Co. Of the plastic individuals/combinations, the plastic combination (PW2) revealed the highest hydrogen efficiency (87.03 %) and H2 efficiency (49.71 %). Regarding the interactions among polyolefins, polyesters, Cl-containing plastics, ternary plastics (PE-PET-PVC) exhibited the higher H2 yield (35.33 mmol/gplastic), hydrogen efficiency (91.40 %), and H2 efficiency (49.14 %) than individual counterparts. The CNTs yield and purity gained from ternary PE-PET-PVC even outperformed these results obtained from individual PE (yield: 326.7 mg/gplasticvs 323.9 mg/gplastic; purity: 93.5 % vs 90.3 %). That was because the chlorinated aryloxy radicals generated from PVC and PET facilitated the cleavage of C (sp3)-H bonds, thereby enhancing the hydrogen extraction and carbon formation. Besides, NiO and NiAl2O4 on the catalyst were converted into NiCl2 by PVC-derived Cl· or HCl, subsequently being reduced into reactive Ni0. Additionally, bimetallic Ni-Fe/HY during CO2-mediated pyrolysis-catalysis displayed the highest H2 yield (55.67 mmol/gplastic), syngas purity (82.39 %), H2 efficiency (62.34 %), and CNTs yield of 367 mg/gplastic, reflecting an apparent synergistically catalytic effect between Ni and Fe. Overall, this study provides a superb solution in heteroatoms-containing plastics upcycling and greenhouse gas emission management.