Browsing by Author "Khabushev, Eldar M."

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  • Activation of Catalyst Particles for Single-walled Carbon Nanotube Synthesis
    (2021-06-01) Khabushev, Eldar M.; Kolodiazhnaia, Julia V.; Krasnikov, Dmitry V.; Nasibulin, Albert G.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    In this work, we evaluate the effect of ferrocene delivery in the reactor on the growth of single-walled carbon nanotubes (SWCNTs) in an aerosol CVD utilizing carbon monoxide as a feedstock. For this purpose, we assess the reactor output parameters varying a gas flow rate through a ferrocene vapor injector in the hot zone with other conditions (temperature, total flow rate, and reactant concentration) being fixed. Our experimental results reveal the adjustment of the ferrocene injection strategy (injector flow rate) to cause a 9-fold improvement in the synthesis yield while preserving the SWCNT properties. We show the catalyst injection optimization to enhance catalyst activation degree as a result of a streamline catalyst delivery, preventing particle over-growth; the experimental data are supported by the computational fluid dynamics. We believe our work to highlight the importance of appropriate aerosol CVD reactor engineering and to facilitate the optimization of reactor productivity, which is one of the fundamental milestones towards SWCNT-based technology.
  • Artificial neural network for predictive synthesis of single-walled carbon nanotubes by aerosol CVD method
    (2019-11-01) Iakovlev, Vsevolod Ya; Krasnikov, Dmitry V.; Khabushev, Eldar M.; Kolodiazhnaia, Julia V.; Nasibulin, Albert G.
     Letter
    We propose to use artificial neural networks to process the experimental data and to predict the performance of the aerosol CVD synthesis of single-walled carbon nanotubes based on Boudouard reaction. We employ five key input parameters of the growth (pressures of CO, CO2 and ferrocene as well as the residence time and the growth temperature) to control the performance of produced nanotube films (yield, mean and standard deviation of the diameter distribution, and defectiveness). The prediction errors were found to be comparable with the corresponding experimental errors. We believe the proposed approach is of great interest for the synthesis of nanocarbons with tailored characteristics.
  • Binder-free LiNi0.8Mn0.1Co0.1O2 electrode enabled by single-walled carbon nanotube coating for Li-ion batteries
    (2024-12-20) Bogdanova, Alisa R.; Obrezkov, Filipp A.; Khabushev, Eldar M.; Kong, Xiangze; Kallio, Tanja
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Herein, we report a solvent-free preparation procedure for a binder-free LiNi0.8Mn0.1Co0.1O2 (NCM811 or NMC811) positive electrode consisting of only 0.2 wt% single-walled carbon nanotubes (SWCNTs) and 99.8 wt% NCM811. SWCNTs form a three-dimensional conductive network within NCM811 particles, facilitating electron transfer across the NCM811 electrode, while maintaining high content of the active material. The binder-free NCM811-SWCNT electrode provides a high discharge specific capacity of ~190 mAh g−1 at 0.2C current rate retaining 38 % more of the initial capacity than a conventional electrode after 200 charge-discharge cycles at 1C. Electrochemical techniques such as operando X-ray diffraction and dilatometry has been applied for the first time to gain a deeper understanding of binder-free electrode structure evolution induced by electrochemical transformations. The data obtained demonstrates a good agreement between macroscopic and microscopic parameters changes for a NCM-SWCNT electrode.
  • A Binder-Free Nickel-Rich Cathode Composite Utilizing Low-Bundled Single-Walled Carbon Nanotubes
    (2024-07-22) Mousavihashemi, Seyedabolfazl; Khabushev, Eldar M.; Lahtinen, Jouko; Bogdanova, Alisa R.; Novikov, Ilya V.; Krasnikov, Dmitry V.; Nasibulin, Albert G.; Kallio, Tanja
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    In this study, the performance of a binder-free LiNi0.6Co0.2Mn0.2O2 (NMC622) positive electrode utilizing single-walled carbon nanotubes (SWCNTs) is investigated and compared to the conventional state-of-the-art NMC622 composite positive electrode. The binder-free electrode has been prepared without using toxic and expensive N-Methyl-2-pyrrolidone (NMP) solvent and it is free-standing that allows a wider range of applications such as flexible devices. Electrochemical techniques such as cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge–discharge reveal that the binder-free positive electrode performance is similar to the conventional composite cathodes, deducing that only ≈1% of SWCNTs perform well not only as a conductive agent but also as a binder. The NMC622 composite electrode with SWCNTs provided specific capacity of 135.8 mAh g−1 at a 5C rate during discharge, with above 97% capacity retention after the rate capability test in a half cell.
  • Direct injection of SWCNTs into liquid after supercritical nitrogen treatment
    (2019-11-01) Kalachikova, Polina M.; Goldt, Anastasia E.; Khabushev, Eldar M.; Eremin, Timofei V.; Ustinovich, Konstantin B.; Grebenko, Artem; Parenago, Olga O.; Zatsepin, Timofei S.; Pokrovskiy, Oleg I.; Obraztsova, Elena D.; Nasibulin, Albert G.
     Letter
    We developed a novel robust technique to produce high-quality dispersions of debundled SWCNTs in aqueous solutions. Direct injection of SWCNTs treated with supercritical nitrogen into the aqueous surfactant solution facilitates the dispersion process without the need of extensive ultrasonication. According to photoluminescence and absorbance measurements, the mild ultrasonic treatment of such dispersions resulted in a higher yield of individual SWCNTs, compared to pristine tubes and tubes collected after the supercritical treatment in the form of powder.
  • Direct measurement of carbon nanotube temperature between fiber ferrules as a universal tool for saturable absorber stability investigation
    (2021-10-30) Galiakhmetova, Diana; Gladush, Yuriy; Mkrtchyan, Aram; Fedorov, Fedor S.; Khabushev, Eldar M.; Krasnikov, Dmitry V.; Chinnambedu-Murugesan, Raghavan; Manuylovich, Egor; Dvoyrin, Vladislav; Rozhin, Alex; Rümmeli, Mark; Alyatkin, Sergey; Lagoudakis, Pavlos; Nasibulin, Albert G.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Single-walled carbon nanotubes (SWCNTs) are widely explored for the ultrashort pulse generation in the fiber lasers enabled by pronounced saturable absorption (SA) effect. Despite many remarkable results demonstrated in the area, degradation of the samples inside the laser cavity limits the widespread use of SWCNT-SA. In the present work, we investigate the degradation mechanism by measuring the temperature of the carbon nanotubes in an operating laser cavity in accordance with the Raman G-band position. We identify the process behind the sample degradation by comparing the burning temperature of the sample with results of thermogravimetric analysis. We apply this approach for the SWCNTs in polyvinyl alcohol polymer matrix and polymer-free SWCNT thin film and demonstrate that these samples undergo different degradation mechanism. Proposed technique provides a useful instrument for optimization of SWCNT-SA for desired ultrafast laser generation.
  • Fine-Tuning of Single-Walled Carbon Nanotube Properties for Transparent Conductive Applications
    (2022) Khabushev, Eldar M.
     School of Chemical Technology | Doctoral dissertation (article-based)
    Single-walled carbon nanotubes (SWCNTs) are a unique material for next-generation electronics, thanks to their outstanding physical properties. In particular, SWCNT-based transparent conductive films (TCFs) are of great interest for replacing indium-tin-oxide in touch screens, displays, and solar cells with a technology development paradigm shifting to stretchable and wearable devices. However, recent advances in the field of SWCNT thin-film production, particularly material performance and synthesis productivity, are insufficient for pushing SWCNTs into the industry. This fact highlights the relevance of research on the efficient synthesis of SWCNTs with tailored characteristics, which is the main focus of the current thesis. Two different aerosol chemical vapor deposition (CVD) reactors based on carbon monoxide disproportionation and hybrid hydrocarbon pyrolysis were thoroughly investigated and used to tackle the challenge of highly conductive SWCNT film synthesis with desired productivity. The systematic study of the carbon monoxide-based system allowed to associate SWCNT structural properties and optoelectrical performance of their films, providing a direction for further optimization. In particular, low defectiveness, thick nanotube diameter, and high length corresponded to the highest optoelectrical performance of the films. The engineering of gas flows in the reactor was carried out to enhance material performance and synthesis productivity. Thus, the investigation of catalyst injection strategy reinforced with CFD simulations helped to reach a 9-fold enhancement of synthesis yield, preserving SWCNT characteristics. Besides, the residence time adjustment was employed for lengthening the produced SWCNTs. Despite its positive effect on length and film sheet resistance, high residence time resulted in elevated diffusion losses on the reactor walls limiting the process productivity. For post-synthesis enhancement of SWCNT optoelectrical properties, a reversible doping technique based on electrochemical gating of the films was developed. The method was evaluated on the samples produced by the carbon monoxide-based reactor, which exhibited a 13-fold drop in sheet resistance at 90% transmittance down to 53 Ω/□. A more complex and multiparametric hydrocarbon-based synthesis, implementing toluene and ethylene as feedstocks, was employed with a focus on overcoming performance-productivity trade-off. The adjustment of synthesis parameters resulted in sheet resistance (at 90% transmittance) value of 57 Ω/□ and yield of 0.24 cm2·L-1, outperforming previous advances. The multiparametric experimental data was also used in the comparative analysis of machine-learning algorithms and their applicability for predicting SWCNT properties. Among the tested algorithms, artificial neural networks were found to provide the lowest error comparable with experimental inaccuracy, coping well with the prediction of sheet resistance.
  • Fine-tuning of spark-discharge aerosol CVD reactor for single-walled carbon nanotube growth: The role of ex situ nucleation
    (2020-03-01) Iakovlev, Vsevolod Ya; Krasnikov, Dmitry V.; Khabushev, Eldar M.; Alekseeva, Alena A.; Grebenko, Artem K.; Tsapenko, Alexey P.; Zabelich, Boris Yu; Kolodiazhnaia, Julia V.; Nasibulin, Albert G.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    We report a development of recently designed apparatus equipped with a spark discharge generator of catalytic nanoparticles for robust aerosol CVD synthesis of single-walled carbon nanotubes. We achieve a profound control over the diameter distribution and the defectiveness of carbon nanotubes produced. By providing a justified comparison of the apparatus with the most abundant aerosol CVD reactor utilizing ferrocene as a catalyst precursor, we reveal the role of the activation procedure: while spark-discharge generator provides aerosol of nanoparticles (ex situ route), the ferrocene vapor decomposes in the nanotube growth zone providing an in situ formation of the catalyst. With other parameters being equal, we reveal the differences in the nanotube growth (diameter and length distribution, yield, defectiveness) employing a comprehensive set of methods (the analysis of differential mobility of the aerosol particles, optical spectroscopy, scanning and transmission electron microscopy, Raman spectroscopy, and atomic force microscopy). We show the ex situ activation in the spark discharge reactor to provide a lower utilization degree of the nanoparticles due to over-coagulation. However, the same method provides an independence of the key performance parameters of the nanotubes opening a room for scaling the apparatus.
  • High-temperature adsorption of nitrogen dioxide for stable, efficient, and scalable doping of carbon nanotubes
    (2024-04-25) Khabushev, Eldar M.; Krasnikov, Dmitry V.; Sainio, Jani; Novikov, Ilya V.; Goldt, Anastasia E.; Fedotov, Stanislav S.; Kallio, Tanja; Nasibulin, Albert G.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    This work is devoted to a novel efficient strategy for single-walled carbon nanotube doping employing heat treatment with nitrogen dioxide (NO2). Unlike numerous reports of unstable NO2 doping at room temperature, our method combines high efficiency and stability, enabled by its temperature-dependent adsorption on the nanotube surface. We reveal that doping stability increases with the treatment temperature reaching maxima at 300 °C avoiding any detrimental effect on nanotube structure and optical transmittance. As a result, we demonstrate doped carbon nanotube transparent conductive films exhibiting competitive performance (in respect to films treated with other dopants) with a less than 50% drop in conductive characteristics for over a year. Thermo-programmed desorption analysis and X-ray photoelectron spectroscopy confirm the preferential formation of long-living adsorbed nitrogen species, such as NO3-groups, as a result of high-temperature treatment. We believe the current work provides a basis for the robust and technologically efficient doping of single-walled carbon nanotubes and related structures at industrial scales, as the developed method could be easily coupled with a continuous technology of carbon nano materials production.
  • Highly efficient doping of carbon nanotube films with chloroauric acid by dip-coating
    (2022-04) Zaremba, Orysia T.; Goldt, Anastasia E.; Khabushev, Eldar M.; Anisimov, Anton S.; Nasibulin, Albert G.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Single-walled carbon nanotube (SWCNT) based transparent and conductive films (TCFs) are one of the most prospective materials for novel flexible and stretchable electronic devices. Development of reproducible and scalable doping procedure is the key step towards the widespread implementation of SWCNT TCFs. Here, we thoroughly investigate a dip-coating technique for SWCNT doping as a promising approach for the practical manufacturing of SWCNT films with high performance. We examine the effect of dip-coating parameters on optical and electrical properties of the films using HAuCl4 solution in isopropyl alcohol (IPA) and in situ investigate doping effects. This method appeared to easily fine-tune the optoelectronic parameters of SWCNT films and achieve a record sheet resistance value of 36 Ohm/sq. at the 90% transmittance in the middle of visible spectral range by increasing a work function value from 4.8 (for pristine SWCNTs) to 6.0 eV. The proposed approach allows efficient, uniform, and reproducible fabrication of highly conductive and transparent SWCNT films and opens an avenue for precise tailoring of SWCNT Fermi level for optoelectronic devices.
  • Joint effect of ethylene and toluene on carbon nanotube growth
    (2022-04-15) Khabushev, Eldar M.; Krasnikov, Dmitry V.; Goldt, Anastasia E.; Fedorovskaya, Ekaterina O.; Tsapenko, Alexey P.; Zhang, Qiang; Kauppinen, Esko I.; Kallio, Tanja; Nasibulin, Albert G.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    This work contributes to the understanding of single-walled carbon nanotube synthesis by an aerosol CVD method using ethylene and toluene as a hybrid carbon source. We evaluated an extensive set of synthesis conditions revealing the role of ferrocene, toluene, and ethylene. We found the fundamental role of ethylene promoting nanotube nucleation and catalyst activation degree at all the concentrations studied, and enhancing nanotube growth at low ethylene content. We observed the interplay effect of toluene and ethylene concentrations on the nanotube growth rate, accompanied by the detrimental effect of toluene on catalyst activation degree. Nevertheless, toluene apparently promotes nanotube crystallinity, increasing the film conductivity while used as an individual carbon source. Adjusting the ethylene and toluene concentrations, we produced carbon nanotube-based transparent and conductive films with an equivalent sheet resistance (at 90% transmittance at 550 nm wavelength) value of 57 Ω/□ at the synthesis yield of 0.24 cm2 L−1, which is at least two times higher than the results reported earlier.
  • Machine learning methods for aerosol synthesis of single-walled carbon nanotubes
    (2023-01-15) Krasnikov, Dmitry V.; Khabushev, Eldar M.; Gaev, Andrey; Bogdanova, Alisa R.; Iakovlev, Vsevolod Ya.; Lantsberg, Anna; Kallio, Tanja; Nasibulin, Albert G.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    This work is devoted to the strategy towards the optimal development of multiparametric process of single-walled carbon nanotube (SWCNT) synthesis. Here, we examine the implementation of machine learning techniques and discuss features of the optimal dataset size and density for aerosol chemical vapor deposition method with a complex carbon source. We employ the dataset of 369 points, comprising synthesis parameters (catalyst amount, temperature, feed of carbon sources) and corresponding carbon nanotube characteristics (yield, quality, structure, optoelectrical figure of merit). Assessing the performance of six machine learning methods on the dataset, we demonstrate Artificial Neural Network to be the most suitable approach to predict the outcome of synthesis processes. We show that even a dataset of 250 points with the inhomogeneous distribution of input parameters is enough to reach an acceptable performance of the Artificial Neural Network, wherein the error is most likely to arise from experimental inaccuracy and hidden uncontrolled variables. We believe our work will contribute to the selection of an appropriate regression algorithm for the controlled carbon nanotube synthesis and further development of an autonomous synthesis system for an “on-demand” SWCNT production.
  • Robust method for uniform coating of carbon nanotubes with V2O5 for next-generation transparent electrodes and Li-ion batteries
    (2023-08-30) Ilatovskii, Daniil A.; Krasnikov, Dmitry V.; Goldt, Anastasia E.; Mousavihashemi, Seyedabolfazl; Sainio, Jani; Khabushev, Eldar M.; Alekseeva, Alena A.; Luchkin, Sergey Yu; Vinokurov, Zakhar S.; Shmakov, Alexander N.; Elakshar, Aly; Kallio, Tanja; Nasibulin, Albert G.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Composites comprising vanadium-pentoxide (V2O5) and single-walled carbon nanotubes (SWCNTs) are promising components for emerging applications in optoelectronics, solar cells, chemical and electrochemical sensors, etc. We propose a novel, simple, and facile approach for SWCNT covering with V2O5 by spin coating under ambient conditions. With the hydrolysis-polycondensation of the precursor (vanadyl triisopropoxide) directly on the surface of SWCNTs, the nm-thick layer of oxide is amorphous with a work function of 4.8 eV. The material recrystallizes after thermal treatment at 600 °C, achieving the work function of 5.8 eV. The key advantages of the method are that the obtained coating is uniform with a tunable thickness and does not require vacuuming or heating during processing. We demonstrate the groundbreaking results for two V2O5/SWCNT applications: transparent electrode and cathode for Li-ion batteries. As a transparent electrode, the composite shows stable sheet resistance of 160 Ω sq−1 at a 90% transmittance (550 nm) - the best performance reported for SWCNTs doped by metal oxides. As a cathode material, the obtained specific capacity (330 mA h g−1) is the highest among all the other V2O5/SWCNT cathodes reported so far. This approach opens new horizons for the creation of the next generation of metal oxide composites for various applications, including optoelectronics and electrochemistry.
  • Single-step extraction of small-diameter single-walled carbon nanotubes in the presence of riboflavin
    (2022-12-22) Kalachikova, Polina M.; Goldt, Anastasia E.; Khabushev, Eldar M.; Eremin, Timofei V.; Zatsepin, Timofei S.; Obraztsova, Elena D.; Larionov, Konstantin V.; Antipina, Liubov Yu; Sorokin, Pavel B.; Nasibulin, Albert G.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    We propose a novel approach to disperse and extract small-diameter single-walled carbon nanotubes (SWCNTs) using an aqueous solution of riboflavin and Sephacryl gel. The extraction of small-diameter semiconducting SWCNTs was observed, regardless of the initial diameter distribution of the SWCNTs. Dispersion of SWCNTs occurs due to the adsorption of π-conjugated isoalloxazine moieties on the surface of small-diameter nanotubes and interactions between hydroxy groups of ribityl chains with water. During the SWCNT extraction, specific adsorption of riboflavin to SWCNTs leads to the minimization of interactions between the SWCNTs and gel media. Our experimental findings are supported by ab initio calculations demonstrating the impact of the riboflavin wrapping pattern around the SWCNTs on their interaction with the allyl dextran gel.
  • Structural, Mechanical, and Optical Properties of Laminate-Type Thin Film SWCNT/SiOxNy Composites
    (2024-11-11) Shmagina, Elizaveta; Antonov, Maksim; Kasikov, Aarne; Volobujeva, Olga; Khabushev, Eldar M.; Kallio, Tanja; Bereznev, Sergei
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The development of new encapsulating coatings for flexible solar cells (SCs) can help address the complex problem of the short lifespan of these devices, as well as optimize the technological process of their production. In this study, new laminate-type protective composite coatings were prepared using a silicon oxynitride thin-film matrix obtained by curing the pre-ceramic polymer perhydropolysilazane (PHPS) through two low-temperature methods: (i) thermal annealing at 180 °C and (ii) exposure to UV radiation at wavelengths of 185 and 254 nm. Single-walled carbon nanotubes (SWCNTs) were used as fillers via dry transfer, facilitating their horizontal orientation within the matrix. The optical, adhesive, and structural properties of the matrix films and SiOxNy/SWCNT composite coatings, along with their long-term stability, were studied using Fourier transform infrared spectroscopy (FTIR), UV-Vis spectroscopy, HR-SEM, spectral ellipsometry, and a progressive-load scratch test. In this work, the optical constants of PHPS-derived films were systematically studied for the first time. An antireflection effect was observed in the composites revealing their two-component nature associated with (i) the refractive index of the SiOxNy matrix film and (ii) the embedding of a SWCNT filler into the SiOxNy matrix. The curing method of PHPS was shown to significantly affect the resulting properties of the films. In addition to being used as protective multifunctional coatings for SCs, both SiOxNy/SWCNT composites and SiOxNy matrix films also function as broadband optical antireflective coatings. Furthermore, due to the very low friction coefficients observed in the mechanical tests, they show potential as scratch resistant coatings for mechanical applications.
  • Structure-dependent performance of single-walled carbon nanotube films in transparent and conductive applications
    (2020-05) Khabushev, Eldar M.; Krasnikov, Dmitry V.; Kolodiazhnaia, Julia V.; Bubis, Anton V.; Nasibulin, Albert G.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    We investigate a complex relationship between structural parameters of single-walled carbon nanotubes (namely, mean length, diameter, and defectiveness) and optoelectrical properties (equivalent sheet resistance) of thin films composed of the nanotubes. We obtained a systematic dataset describing the influence of CO2 concentration and growth temperature. On the basis of the experimental results, we prove the high Raman peak ratio (IG/ID), length, and diameter of the nanotubes to decrease the equivalent sheet resistance of the nanotube-based film. The approach employed highlights the change in the nanotube growth mechanism at the temperature coinciding with the phase transition between α-Fe and γ-Fe catalyst phases. We believe this work to be of high interest for researchers working not only in the field of transparent and conductive films based on nanocarbons, but also for those who reveals the fundamentals of the nanotube growth mechanism.