Production Of Carbon Nanomaterials Research Articles

Sustainable production of carbon nanomaterials based on TPT backsheet pyrolysis from end-of-life photovoltaic modules

The environmentally friendly recycling of end-of-life (EoL) photovoltaic modules is a crucial pathway to achieving “carbon neutrality.” However, currently, most efforts are primarily focused on the recovery of valuable metals, neglecting the utilization of TPT (Tedlar/PET/Tedlar) plastic backsheet. This work develops a two-stage pyrolysis process for TPT decomposition and which can convert into high-value nanocarbon materials and hydrogen under the catalysis of Ni and Fe nanometal particles. The pyrolysis behavior of TPT backplates was systematically investigated, the gas chromatography results reveal that the pyrolysis products primarily consisted of CO2, CO, CH4, CH3CHO, and other small molecules, alongside sizeable residual compounds under the catalytic degradation process. The resulting hydrocarbons play an important role as carbon sources in the formation of carbon nanomaterials and hydrogen generation. The study thoroughly discusses the effects of different catalyst on pyrolysis gas species and components, fixed carbon content, and nanocarbon morphology. Molecular dynamics simulations based on the reactive force field (ReaxFF) was performed to analyze the pyrolysis products. Finally, a gas–liquid-solid physical model was proposed to interpret the growth process of the carbon nanomaterials under Ni-Fe nanometallic catalysis.

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.

Catalytic pyrolysis of high-density polyethylene for the production of carbon nanomaterials: effect of pyrolysis temperature

Catalytic pyrolysis of high-density polyethylene for the production of carbon nanomaterials: effect of pyrolysis temperature

Iron-containing polyoxotungstophosphates and their thermolysis products

Thermolysis of ferrocenium tungstophosphate [(C5H5)2Fe]3[PW12O40]∙H2O and tungstophosphatoferrates with the general formula of Cat4[PW11O39Fe(H2O)]∙ m H2O, where Cat = (NH4)+, Rb+, Cs+, (CH3)4N+, with the Keggin anion structure were studied using differential scanning calorimetry, infrared spectroscopy, X-ray phase analysis, and electron microscopy. The crystalline products of their thermal decomposition - phases with the structure of pyrochlore and tungsten bronzes - were identified. The synthesized compounds are catalysts for the oxidation reactions of organic compounds and the production of carbon nanomaterials.

ACTUAL METHODS OF ELECTROCHEMICAL SURFACE TREATMENT

In this work, we have studied the methods of electrochemical processing of materials in order to give them new functional properties. Experimental data on the production of corrosion-resistant coatings based on Zn-Ni and Zn-Co alloys from ammonium oxalate electrolytes and the study of their protective properties are presented. The questions of electrochemical production of carbon nanomaterials by anodic exfoliation of graphite in sulfuric acid electrolytes are considered. The influence of the dispersed phase of electrochemically exfoliated graphite on the electrodeposition of tin from sulfate and stannate electrolytes has been established. The influence of the additive on the aging of tin coatings and their ability to solderability was studied. Data are given on the effect of chloride ions in a solution of chemical polishing of brass on solderability. For citation: Shekhanov R.F., Gridchin S.N., Bratkov I.V., Ershova T.V., Dontsov M.G. Actual methods of electrochemical surface treatment. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 7. P. 151-158. DOI: 10.6060/ivkkt.20236607. 6841j.

Carbon nanomaterial production using waste plastic pyrolysis over a new catalyst made from mining residues: Effect of plastic type

Pyrolysis and in-line catalytic decomposition of plastic waste were performed for the production of carbon nanomaterials (CNMs) and hydrogen. A new catalyst, Ni-UGSO (Nickel-UpGraded Slug Oxide), was used in a continuous mode, and its activity was compared to that of a typical Fe/Al2O3 catalytic formulation. Moreover, the pyrolysis-catalysis of different plastics (virgin high-density polyethylene (HDPE), used HDPE, and mixed plastics) was studied to investigate the effect of the plastic type on the quantity and quality of the produced CNMs. Ni-UGSO exhibited the highest catalytic activity for the production of CNMs and H2 of the two formulations tested, with yields of 56.6 kg/100 kgplastic and 13.2 kmol/100 kgplastic, respectively. The high activity and performance of Ni-UGSO were attributed to the synergistic effect of the Ni and Fe in Ni-UGSO. Scanning transmission electron microscopy (STEM) results revealed that most of the produced carbon was in the form of carbon nanofilaments (CNFs) of different diameters, ranging from 8 to 90 nm. The use of mixed plastics as a feedstock decreased the yield of CNMs by 10 wt%, and a layer of amorphous carbon covered the CNFs. This layer is due to the presence of polystyrene (PS), polyethylene terephthalate (PET), and other contaminants in the feedstock. Raman spectroscopy showed that the CNFs produced from used HDPE had the highest intensity ratio G/D (1.13).

Production of carbon nanomaterials and syngas from biogas reforming and decomposition on one-pot mesoporous nickel alumina catalysts

Biogas, a renewable energy source, is primarily composed of CH4 and CO2. It is a promising alternative to fossil fuels and can be used directly for electricity production as well as heat generation via combustion. Concerns about climate change and a greater emphasis on renewable energy sources have recently increased interest in biogas utilization. In this context, biogas reforming and decomposition (BRD) into synthesis gas and carbon nanofibers (CNFs) is viewed as a new and attractive way of efficiently valorising biogas. In this study, Ni-loaded (i.e., 20, 50 wt%) mesoporous alumina materials were prepared using one-pot evaporation-induced self-assembly method for BRD. Synthesized materials were characterized by various techniques: N2-physisorption, X-ray diffraction, temperature-programmed reduction, scanning electron microscopy, and thermal gravimetric analysis. Results showed that textural and structural properties of synthesised materials differed with Ni loading. High Ni-loaded catalyst displayed higher surface area, pore volume, pore size distribution, and average particle size which is the result of deposition of Ni species outside alumina grains creating thus, surface defects. BRD results were greatly influenced by Ni content with Ni50%Al2O3 reflecting catalytic behaviour similar to those expected for pure methane decomposition. Most importantly, this catalyst was also capable of generating, selectively, interesting carbon nanofibers.

Catalytic Properties of Bulk (1–x)Ni–xW Alloys in the Decomposition of 1,2-Dichloroethane with the Production of Carbon Nanomaterials

Catalytic Properties of Bulk (1–x)Ni–xW Alloys in the Decomposition of 1,2-Dichloroethane with the Production of Carbon Nanomaterials

Green synthesis of carbon nanomaterials from sugarcane bagasse using bio-silica supported bimetallic nickel-based catalysts

Sugarcane bagasse (SCB) can be considered as an inexpensive and abundant source for the production of valuable carbon nanomaterials (CNMs). Herein, the synthesis of CNMs via sugarcane bagasse (SCB) pyrolysis was investigated using a simple two-stage process. Bio-silica extracted from rice husk (RH-SiO2) was loaded with 50%Ni, 40%Ni-10%Cu, 40%Ni-10%Mo, and 40%Ni-10%Co and evaluated as catalysts for the production of CNMs from pyrolysis products. The fresh catalysts were characterized by XRD, H2-TPR, and CO2-TPD analyses, while the spent catalysts were characterized using TEM and Raman spectroscopy. The XRD and TPR results of the fresh catalysts demonstrated the existence of non-interacted NiO species in the monometallic Ni/RH-SiO2 catalyst. However, mixed oxides of NixCu1-xO, NiMoO4, and NiCo2O4 species were presented in Ni-Cu, Ni-Mo, and Ni-Co catalysts, respectively, in addition to non-interacted NiO species. TEM images revealed the presence of both carbon nanotubes (CNTs) and graphene nanosheets (GNSs) depending on the catalyst type. The results showed that the presence of mixed oxide species in the catalyst was associated with CNTs formation, while the existence of agglomerated Ni particles was correlated to GNSs formation. The catalytic activity of the catalysts in terms of carbon yield was arranged as follows: 50%Ni > 40%Ni-10%Co > 40%Ni-10%Cu > 40%Ni-10%Mo. Raman spectra proved the production of high-quality CNMs using all Ni-based catalysts.

Electrochemical Synthesis of Unique Nanomaterials in Ionic Liquids.

The review considers the features of the processes of the electrochemical synthesis of nanostructures in ionic liquids (ILs), including the production of carbon nanomaterials, silicon and germanium nanoparticles, metallic nanoparticles, nanomaterials and surface nanostructures based on oxides. In addition, the analysis of works on the synthesis of nanoscale polymer films of conductive polymers prepared using ionic liquids by electrochemical methods is given. The purpose of the review is to dwell upon an aspect of the applicability of ILs that is usually not fully reflected in modern literature, the synthesis of nanostructures (including unique ones that cannot be obtained in other electrolytes). The current underestimation of ILs as an electrochemical medium for the synthesis of nanomaterials may limit our understanding and the scope of their potential application. Another purpose of our review is to expand their possible application and to show the relative simplicity of the experimental part of the work.

Green Synthesis of Tunable Fluorescent Carbon Quantum Dots from Lignin and Their Application in Anti-Counterfeit Printing.

Lignin converted to carbon quantum dots (CQDs) attracts tremendous attention for large-scale production of carbon nanomaterials and value-added disposal of biomass wastes (such as the black liquor from pulping industry and the residue from hydrolysis of biomass). The green synthesis of lignin-derived CQDs is reported via a facile two-step method with the adjustment of acid additives containing N or S. The resulting series of CQDs exhibit bright fluorescence in gradient colors from blue to yellowish green, among which the N, S co-doped CQDs with the addition of 2,4-diaminobenzene sulfonic acid show an optimal fluorescence quantum yield (QY) of 30.5%. The red-shift photoluminescence emission behaviors of these CQDs can be attributed to the increased graphitization degree and reduced optical energy band gaps (2.47 → 2.17 eV) with regard to the incorporation of various heteroatoms. The improved fluorescence QYs are consistent with the variation trend of the increased N/C content in the CQDs. The yellowish green-emissive CQDs with bright fluorescence, strong water solubility, and excellent chemical stability perform well in anti-counterfeiting printing. The promising and sustainable approach for the synthesis of tunable fluorescent CQDs exhibits the value-added utilization of lignin for the fluorescence ink production.

Sampling and concentration of polycyclic aromatic hydrocarbons from exhaust gases from a plant for synthesis of carbon nanomaterials

Currently, there is an increase in the production of carbon nanomaterials in the world, which is associated with their unique physical and mechanical properties and their use in various fields of science, industry and technology. Investigation of the chemical composition of waste gases from a propane-butane mixture pyrolysis unit during the synthesis of carbon nanomaterials is of scientific and applied value, since it allows one to study both the chemistry of the pyrolysis process of hydrocarbon mixtures and determine the degree of toxicity of waste gas from pyrolysis units. The quantitative determination of polycyclic aromatic hydrocarbons in the gaseous products of pyrolysis of a propane-butane mixture during the synthesis of carbon nanomaterials has shown that when sampling with a small amount of the Supelpak-2 adsorbent, which is widely used in international and domestic methods, efficient capture of multinuclear aromatic hydrocarbons is not ensured. Therefore, an important research issue is the development of a simple and effective method for sampling polycyclic aromatic hydrocarbons with their subsequent GC-MS analysis. The principal essence of the technique is the impregnation of two fiberglass filters with an organic low-volatile solvent – diethylene glycol, tetraethylene glycol or dimethyl sulfoxide. The latter is characterised by the highest extracting power in relation to polycyclic aromatic hydrocarbons. The developed technique makes it possible to increase the efficiency of capturing multinuclear aromatic hydrocarbons (with four or more rings in a molecule) to 96–98 % compared to a solid adsorbent under equal conditions (pyrolysis conditions, weight of adsorbent equal with filters impregnated with a solvent), where the degree of their extraction is 1–5 %. The established values of the degree of recovery of the measured components are explained by the high extracting ability of dimethyl sulfoxide in relation to multinuclear aromatic hydrocarbons.

The novel method of synthesis of nanostructured materials for the enhancing recovery in oil displacement technologies

The work is dedicated to a research into the physicochemical aspects of carbon nanopowder production from the gas phase by the pyrolysis of the initial precursors in a cyclic adiabatic process in a flow-through chemical compression reactor (CCR). The method allows the production of carbon nanomaterials, such as the carbon nanoparticles and globular soot particles, as well, as the core-shell structures representing the 4–7 nm composite particles with a SiC crystal core covered with graphene layers. Products have controlled and reproducible properties, and output capacity of the method is sufficient for technological purposes. The nanopowders are characterized by high-resolution transmission electron (TEM) and scanning electron (SEM) microscopy, X-ray diffraction analysis and Raman spectroscopy. The nanomaterials were used to manufacture their aqueous suspensions - nanofluids, which have shown their effectiveness in enhancing oil recovery in oil displacement technologies.

Technology for the production of carbon nanomaterials by pyrolysis

The processes of oil production and preparation involve the formation of a mixture of various hydrocarbon gases, otherwise called associated petroleum gas. Today most of associated petroleum gas produced is burned, causing damage to the natural environment, or used as an energy supply for technological equipment. At the same time, associated petroleum gas can be used as a valuable raw material to produce various chemicals. In the article, the existing methods of APG utilization are considered, and the relatively simplest and most environmentally friendly pyrolysis method is proposed. A comparative analysis of the methods of mixing raw materials was carried out, as a result of which it was revealed that the mechanical and vibration methods are considered the most rational. An experimental installation for processing petroleum associated gas by pyrolysis is presented. The results of experimental studies of the production of carbon fiber nanomaterials and hydrogen are presented. Gas (CH4) obtained by utilization of hydrocarbon-containing waste (oil sludge) was used as a feedstock. The average yield of the target products was 81 l/h for hydrogen and 325.5 g/h for nanofiber carbon.

Scalable Fabrication of Carbon Nanomaterials by Electrochemical Dual-Electrode Exfoliation of Graphite in Hydroxide Molten Salt

Simultaneous electroexfoliation of graphite on both cathode and anode in molten NaOH–KOH was proposed and found to be a feasible method for the mass production of carbon nanomaterials. During this electrolysis process, alkaline cations and hydroxide ions were intercalated into the bulk graphite and then discharged to generate alkaline metals and hydrogen at the cathode, and oxygen at the anode. The simultaneous intercalation on both electrodes and the escape of gas enhanced the exfoliation efficiency, leading to a high production rate of nanostructured carbon exceeding 26.9 g h–1. The four to seven layers of graphene nanosheets with negligible defect (ID/IG = 0.079) and low oxidation degree (C/O ratio = 20.32) were obtained through cathodic exfoliation, while the corresponding anodic exfoliation products featured more oxygen-containing functional groups (7.59%). This introduced method was beneficial for the mass production of carbon materials in a highly efficient way.

Facile preparation and characterization of fibrous carbon nanomaterial from waste polyethylene terephthalate

Efficient reduction of environmental pollution caused by waste polyethylene terephthalate (PET) and production of carbon nanomaterials are desirable for nanotechnology, printable electronics, composites and environment protection. Here we report a simple top-down micro/nano-fabrication process to prepare fibrous carbon nanomaterial from waste PET bottles. This process is highly efficient, facile, and catalyst-free in preparing fibrous carbon nanomaterial with promising hydrophobic and electrical properties. The fibrous carbon nanomaterial can be used both in the form of sheet or powder, and it supplies a versatile surface for preparing novel carbon-based composites with significant optical properties and conductivity. The prepared carbon nanomaterial from waste PET has also been used in fabricating strain sensor with good durability.

Catalyst-free fabrication of one-dimensional N-doped carbon coated TiO2 nanotube arrays by template carbonization of polydopamine for high performance electrochemical sensors

One-dimensional (1D) carbon nanomaterials have extensively explored to fabricate high performance electrochemical sensors for the merits such as high surface area and fast electron transfer kinetics. However, catalytic production of carbon nanomaterials often suffers from misinterpretations of electrochemical signals from the catalyst residue and complicated production steps. Herein, we reported a catalyst-free method to produce 1D N-doped carbon coated TiO2 nanotube arrays (N-doped C/TiO2 NTAs) by template carbonization of polydopamine nanofilm coated anodized TiO2 NTAs. The N-doped C/TiO2 NTAs possesses a uniform structure with an inner diameter for an individual nanotube of about 80 nm and a length of about 8 µm. The carbon coating is about 10 nm in thickness and is doped by nitrogen from the polydopamine precursor. The N-doped C/TiO2 NTAs electrode exhibits an extremely high electrochemical activity with the heterogeneous charge transfer rate constants k0 greater than 0.5 cm/s for Fe(CN)63−/4− redox couple. Simultaneous determination of ascorbic acid, dopamine and uric acid has been demonstrated with the linear ranges of 100–3000 μM, 5–50 μM and 0.1–150 μM, respectively and detection limits (S/N = 3) of 1.8 μM, 0.015 μM and 0.11 μM, respectively.

Effects of reduced graphene oxide on humic acid-mediated transformation and environmental risks of silver ions

The reduction of Ag+ mediated by natural organic matters has been demonstrated to be an important process of Ag+ transformation and would influence the risks of Ag+ and Ag-containing materials in aquatic environment. Considering the large production of carbon nanomaterials (CNMs) and their inevitable release into the environment, the effects of CNMs on Ag transformation are of considerable interest. This study demonstrated that the humic acid-mediated reduction of Ag+ to free Ag nanoparticles (AgNPs) in aqueous phase was suppressed by coexisting reduced graphene oxide (rGO). A large amount of Ag+ was reduced on rGO surface, resulting in the generation of AgNPs-rGO composites. rGO at concentrations of 1–2 orders of magnitude lower than those of Ag+ would exhibit significant effects. The X-ray absorption fine structure spectroscopy study showed that Ag+ was first adsorbed on rGO surface cooperatively with humic acid and then rapidly reduced to AgNPs. The hydroxylic-OH on rGO could participate in the AgNPs formation and was oxidized to carbonyl during the reduction of Ag+. Additionally, the formed AgNPs-rGO had a relatively lower environmental risk compared to AgNPs or rGO alone. Overall, these results improve our understanding of the interaction between CNMs and Ag+ in aquatic systems.

Supercritical Fluids as Reaction Media for Scalable Production of Carbon Nanomaterials

We have demonstrated scalable and selective synthesis of carbon nanotubes (CNTs), carbon nanofibers (CNFs), and onion-like carbons (OLCs) in a batch reactor using supercritical fluids (SCFs) as rea...

Hydrogen production by methane decomposition using bimetallic Ni–Fe catalysts

The catalytic methane decomposition is the leading method for COx-free hydrogen and carbon nanomaterial production. In the present study, calcium-silicate based bimetallic Ni–Fe catalysts have been prepared and used to decompose the methane content of the ‘product gas’ obtained in the biomass gasification process for increasing total hydrogen production. Al2O3 was used as secondary support on calcium silicate based support material where Ni or Ni–Fe were doped by co-impregnation technique. The activity of catalysts was examined for diluted 6% methane-nitrogen mixture in a tubular reactor at different temperatures between 600 °C and 800 °C under atmospheric pressure, and data were collected using a quadrupole mass spectrometer. Catalysts were characterized by XRD, SEM/EDS, TEM, XPS, ICP-MS, BET, TPR, and TGA techniques. The relation between structural and textural properties of catalysts and their catalytic activity has been investigated. Even though the crystal structure of catalysts had a significant effect on the activity, a direct relation between the BET surface area and the activity was not observed. The methane conversion increased by increasing temperature up to 700 °C. The highest methane conversion has been obtained as 69% at 700 °C with F3 catalyst which has the highest Fe addition, and the addition of Fe improved the stability of catalysts. Moreover, carbon nanotubes with different diameter were formed during methane decomposition reaction, and the addition of Fe increased the formation tendency.