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Funding Information: This work was supported by Russian Foundation for Basic Research Grant No. 18-29-06071. We thank the Council on grants of the President of the Russian Federation grant number HIII-1330.2022.1.3. F.F. and D.K. thank Russian Science Foundation, Grant No. 21-73-10288 for support of impedance spectroscopy studies. Publisher Copyright: © 2022 American Chemical Society. All rights reserved. Stretchable and flexible electronics has attracted broad attention over the last years. Nanocomposites based on elastomers and carbon nanotubes are a promising material for soft electronic applications. Despite the fact that single-walled carbon nanotube (SWCNT) based nanocomposites often demonstrate superior properties, the vast majority of the studies were devoted to those based on multiwalled carbon nanotubes (MWCNTs) mainly because of their higher availability and easier processing procedures. Moreover, high weight concentrations of MWCNTs are often required for high performance of the nanocomposites in electronic applications. Inspired by the recent drop in the SWCNT price, we have focused on fabrication of elastic nanocomposites with very low concentrations of SWCNTs to reduce the cost of nanocomposites further. In this work, we use a fast method of coagulation (antisolvent) precipitation to fabricate elastic composites based on thermoplastic polyurethane (TPU) and SWCNTs with a homogeneous distributionof SWCNTs in bulk TPU. Applicability of the approach is confirmed by extra low percolation threshold of 0.006 wt % and, as a consequence, by the state-of-the-art performance of fabricated elastic nanocomposites at very low SWCNT concentrations for strain sensing (gauge factor of 82 at 0.05 wt %) and EMI shielding (efficiency of 30 dB mm-1at 0.01 wt %).

Funding Information: The authors thank Prof. Esko I. Kauppinen and Dr. Fedor Fedorov for fruitful discussions. E.M.Kh. and T.K. acknowledge Academy of Finland (Profi 5 Project) and Finnish National Agency for Education (the EDUFI fellowship grant). D.V.K. acknowledges RSF (grant No. 20-73-10256; ANN, optimal dataset). D.V.K and A.G.N. acknowledge Council on grants of RF (grant No НШ-1330.2022.1.3). Publisher Copyright: © 2022 The Authors 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.

Funding Information: A.A.M. and A.G.N. thanks RFBR research project ? 20-32-90233 for support in experimental part of the work. D.V.K. thanks Russian Science Foundation grant No. 20-73-10256 for support in synthesis of aerosol SWCNT films. V.D. thanks the Russian Science Foundation (Grant No. 17-72-30006) for the support in characterization of pulse laser generation. Funding Information: A.A.M. and A.G.N. thanks RFBR research project № 20-32-90233 for support in experimental part of the work. D.V.K. thanks Russian Science Foundation grant No. 20-73-10256 for support in synthesis of aerosol SWCNT films. V.D. thanks the Russian Science Foundation (Grant No. 17-72-30006 ) for the support in characterization of pulse laser generation. Publisher Copyright: © 2021 Elsevier Ltd 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.

The architecture of transparent contacts is of utmost importance for creation of efficient flexible light-emitting devices (LEDs) and other deformable electronic devices. We successfully combined the newly synthesized transparent and durable silicone rubbers and the semiconductor materials with original fabrication methods to design LEDs and demonstrate their significant flexibility. We developed electrodes based on a composite GaP nanowire-phenylethyl-functionalized silicone rubber membrane, improved with single-walled carbon nanotube films for a hybrid poly(ethylene oxide)-metal-halide perovskite (CsPbBr3) flexible green LED. The proposed approach provides a novel platform for fabrication of flexible hybrid optoelectronic devices.

The films of single-walled carbon nanotubes (SWCNTs) are a promising material for flexible transparent electrodes, which performance depends not only on the properties of individual nanotubes but also, foremost, on bundling of individual nanotubes. This work investigates the impact of densification on optical and electronic properties of SWCNT bundles and fabricated films. Our ab initio analysis shows that the optimally densified bundles, consisting of a mixture of quasi-metallic and semiconducting SWCNTs, demonstrate quasi-metallic behavior and can be considered as an effective conducting medium. Our density functional theory calculations indicate the band curving and bandgap narrowing with the reduction of the distance between nanotubes inside bundles. Simulation results are consistent with the observed conductivity improvement and shift of the absorption peaks in SWCNT films densified in isopropyl alcohol. Therefore, not only individual nanotubes but also the bundles should be considered as building blocks for high-performance transparent conductive SWCNT-based films.

We propose a simple dumbbell-shaped scheme of a Holmium-doped fiber laser incorporating a minimum number of optical elements. Mode-locking regimes were realized with the help of polymer-free single-walled carbon nanotubes (SWCNTs) synthesized using an aerosol (floating catalyst) CVD method. We show that such a laser scheme is structurally simple and more efficient than a conventional one using a ring cavity and a similar set of optical elements. In addition, we investigated the effect of SWCNT film transmittance, defined by the number of 40 nm SWCNT layers on the laser’s performance: operating regimes, stability, and self-starting. We found that three SWCNT layers with an initial transmittance of about 40% allow stable self-starting soliton mode-locking at a wavelength of 2076 nm with a single pulse energy of 0.6 nJ and a signal-to-noise ratio of more than 60 dB to be achieved.

Publisher Copyright: © 2022 by the authors. Carbon-encapsulated iron nanoparticles (Fe@C) with a mean diameter of 15 nm have been synthesized using evaporation–condensation flow–levitation method by the direct iron-carbon gas-phase reaction at high temperatures. Further, Fe@C were stabilized with bovine serum albumin (BSA) coating, and their electromagnetic properties were evaluated to test their performance in magnetic hyperthermia therapy (MHT) through a specific absorption rate (SAR). Heat generation was observed at different Fe@C concentrations (1, 2.5, and 5 mg/mL) when applied 331 kHz and 60 kA/m of an alternating magnetic field, resulting in SAR values of 437.64, 129.36, and 50.4 W/g for each concentration, respectively. Having such high SAR values at low concentrations, obtained material is ideal for use in MHT.

We propose a novel approach to enhance optoelectronic performance of single-walled carbon nanotubes (SWCNTs) for transparent conducting film applications. The method provides fine and reversible tuning of optoelectrical properties of SWCNT films over a wide range of parameters. Using imidazolium-based ionic liquid with a wide electrochemical window (BMIM-PF6), we achieved the film sheet resistance as low as 53 Ω/sq at the 90% transmittance, thereby shifting the SWCNT Fermi level up to 1.4 eV. We believe the results to promote collateral research of adjustable tuning of the electronic structure of carbon nanomaterials as promising components for future electronics, electrochromic devices, and ionotronics.

We demonstrate a simple and resource-efficient approach for rapid purification of single-walled carbon nanotube (SWCNT) films from catalyst impurities by Joule heating in a vacuum. As a result, the catalyst concentration decreases by a factor of 27 (from 17 to 1600 °C for 2 min. Moreover, the nanotube structure remains almost intact as the purified films show a high ratio of intensities of G to D bands of Raman spectrum IG/ID = 180. The technique perfectly fits for the devices based on free-standing carbon nanotube films such as protective membranes, infrared detectors, and sound generators. For purified SWCNT films, we show the signal-to-noise ratio for the bolometers to increase by a factor of 2.5 and 24% sound pressure gain for the air-coupled thermophones. The method can be easily extended to other applications, for instance, the SWCNT-based devices of limited liquid and harsh reagent tolerance like nanotube aerogels and drug delivery systems.

Funding Information: The authors thank Anton Bubis and MIPT Shared Facilities Center for the help with scanning electron microscopy. E.M.Kh. and D.V.K. acknowledge Russian Science Foundation grant No. 20-73-10256 (synthesis of SWCNTs and optical measurements). E.M.Kh. and T.K. acknowledge Academy of Finland project No. 320167 (PREIN Flagship - Aalto University). Q.Zh. and E.I.K. acknowledge Academy of Finland project No. 316572 (CNTstress). A.G.N. and A.E.G. acknowledge the Russian Science Foundation (project No. 17-19-01787 - doping of carbon nanotubes). E.I.K. acknowledge the Academy of Finland for Mobility Grant (application number 334466). A.P.Ts. acknowledges the EDUFI Fellowship (No. TM-19-11079) from the Finnish National Agency for Education and the Magnus Ehrnrooth Foundation (the Finnish Society of Sciences and Letters) for personal financial support. This work made use of the Aalto University Otanano, RAMI and Bioeconomy infrastructures. Funding Information: The authors thank Anton Bubis and MIPT Shared Facilities Center for the help with scanning electron microscopy. E.M.Kh. and D.V.K. acknowledge Russian Science Foundation grant No. 20-73-10256 (synthesis of SWCNTs and optical measurements). E.M.Kh. and T.K. acknowledge Academy of Finland project No. 320167 (PREIN Flagship - Aalto University ). Q.Zh. and E.I.K. acknowledge Academy of Finland project No. 316572 (CNTstress). A.G.N. and A.E.G. acknowledge the Russian Science Foundation (project No. 17-19-01787 - doping of carbon nanotubes). E.I.K. acknowledge the Academy of Finland for Mobility Grant (application number 334466). A.P.Ts. acknowledges the EDUFI Fellowship (No. TM-19-11079) from the Finnish National Agency for Education and the Magnus Ehrnrooth Foundation (the Finnish Society of Sciences and Letters ) for personal financial support. This work made use of the Aalto University Otanano, RAMI and Bioeconomy infrastructures. Publisher Copyright: © 2021 Elsevier Ltd 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.

We examined the effect of hydrogen on the growth of single-walled carbon nanotubes in the aerosol (a specific case of the floating catalyst) chemical vapor deposition process using ethylene as a carbon source and ferrocene as a precursor for a Fe-based catalyst. With a comprehensive set of physical methods (UV-vis-NIR and Raman spectroscopies, transmission electron microscopy, scanning electron microscopy, differential mobility analysis, and four-probe sheet resistance measurements), we showed hydrogen to inhibit ethylene pyrolysis extending the window of synthesis parameters. Moreover, the detailed study at different temperatures allowed us to distinguish three different regimes for the hydrogen effect: pyrolysis suppression at low concentrations (I) followed by surface cleaning/activation promotion (II), and surface blockage/nanotube etching (III) at the highest concentrations. We believe that such a detailed study will help to reveal the complex role of hydrogen and contribute toward the synthesis of single-walled carbon nanotubes with detailed characteristics.

Funding Information: The authors thank Mr. Andrei Starkov for illustrations and Mrs. Anastasiya Grebenko for assistance with sample synthesis. This work was performed using equipment of MIPT Shared Facilities Center. The authors acknowledge Vadim Khrapai and Evgeny Tikhonov (ISSP) for assistance with low temperature measurements and professor Galina Tsirlina (MSU) for fruitful discussions. The authors are also grateful to Salavat Khasanov for assistance and verification of XRD measurements. The authors thank the Helmholtz‐Zentrum Berlin für Materialien und Energie for the allocation of synchrotron radiation beamtime. Computations were done at the Finnish IT Center for Science, CSC. Russian Foundation for Basic Research grant # 19‐32‐90143 (A.K.G., A.G.N.). German Federal Ministry of Education and Research (BMBF) grant no. 05K19KER (A.A.M.). Russian Science Foundation No. 21‐19‐00226 (D.V.K., graphene synthesis). Russian Science Foundation No. 21‐72‐20050 (B.P.G., THz‐FIR spectroscopy). Ministry of Science and Higher Education of the Russian Federation within the governmental order for Boreskov Institute of Catalysis project АААА‐А21‐121011390011‐4 (A.N.S.). Partially supported by the Ministry of Science and Higher Education of the Russian Federation No. FSMG‐2021‐0005 (V.S.V., ARPES studies) and Russian Science Foundation No. 21‐72‐30026 (V.S.V, STM Studies). The work was supported by the Council on grants of the President of the Russian Federation grant number НШ‐1330.2022.1.3. Publisher Copyright: © 2022 The Authors. Advanced Science published by Wiley-VCH GmbH Following the game-changing high-pressure CO (HiPco) process that established the first facile route toward large-scale production of single-walled carbon nanotubes, CO synthesis of cm-sized graphene crystals of ultra-high purity grown during tens of minutes is proposed. The Boudouard reaction serves for the first time to produce individual monolayer structures on the surface of a metal catalyst, thereby providing a chemical vapor deposition technique free from molecular and atomic hydrogen as well as vacuum conditions. This approach facilitates inhibition of the graphene nucleation from the CO/CO2 mixture and maintains a high growth rate of graphene seeds reaching large-scale monocrystals. Unique features of the Boudouard reaction coupled with CO-driven catalyst engineering ensure not only suppression of the second layer growth but also provide a simple and reliable technique for surface cleaning. Aside from being a novel carbon source, carbon monoxide ensures peculiar modification of catalyst and in generalopens avenues for breakthrough graphene-catalyst composite production.

Funding Information: V.N. thanks the Russian Foundation for Basic Research (RFBR project No. 19-32-60040) for PDMS/MW membrane fabrication and optical measurements. V.F. thanks the Russian Foundation for Basic Research (RFBR project No. 19-32-60037) for the support of the MBE growth. V.N. and F.K. thank the support from the Russian Foundation for Basic Research (grant 20-32-90182) for electrical measurements. V.N., F.K., R.I. and I.M. thank the Russian Scientific Foundation (RSF project No. 20-19-00256) for chemical treatment of PDMS. V.N., V.F., A.M., F.K. and K.S. thank the Ministry of Science and Higher Education of the Russian Federation (FSRM-2020-0005) for the general support. E.M. thanks the Basic Research Program at the National Research University Higher School of Economics (HSE University) in 2021 for optical measurements. N.A.-M. and M.T. thank ITN Marie Curie project INDEED (grant No. 722176) for GaPAs NW/PDMS membrane investigation. This work received financial support from Partenariats Hubert Curien Kolmogorov project No. 43784UJ and Indo French Centre for the Promotion of Advanced Research (CEFIPRA) Project No. 6008-1. A.G.N. acknowledges the Russian Scientific Foundation (RSF project No. 21-72-20050) for synthesis of SWCNTs. Funding Information: Funding: V.N. thanks the Russian Foundation for Basic Research (RFBR project No. 19-32-60040) for PDMS/MW membrane fabrication and optical measurements. V.F. thanks the Russian Foundation for Basic Research (RFBR project No. 19-32-60037) for the support of the MBE growth. V.N. and F.K. thank the support from the Russian Foundation for Basic Research (grant 20-32-90182) for electrical measurements. V.N., F.K., R.I. and I.M. thank the Russian Scientific Foundation (RSF project No. 20-19-00256) for chemical treatment of PDMS. V.N., V.F., A.M., F.K. and K.S. thank the Ministry of Science and Higher Education of the Russian Federation (FSRM-2020-0005) for the general support. E.M. thanks the Basic Research Program at the National Research University HigherSchool of Economics (HSE University) in 2021 for optical measurements. N.A.-M. and M.T. thank ITN Marie Curie project INDEED (grant No. 722176) for GaPAs NW/PDMS membrane investigation. This work received financial support from Partenariats Hubert Curien Kolmogorov project No. 43784UJ and Indo French Centre for the Promotion of Advanced Research (CEFIPRA) Project No. 6008-1. A.G.N. acknowledges the Russian Scientific Foundation (RSF project No. 21-72-20050) for synthesis of SWCNTs. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. We demonstrate flexible red light-emitting diodes based on axial GaPAs/GaP heterostruc-tured nanowires embedded in polydimethylsiloxane membranes with transparent electrodes involv-ing single-walled carbon nanotubes. The GaPAs/GaP axial nanowire arrays were grown by molecular beam epitaxy, encapsulated into a polydimethylsiloxane film, and then released from the growth substrate. The fabricated free-standing membrane of light-emitting diodes with contacts of single-walled carbon nanotube films has the main electroluminescence line at 670 nm. Membrane-based light-emitting diodes (LEDs) were compared with GaPAs/GaP NW array LED devices processed directly on Si growth substrate revealing similar electroluminescence properties. Demonstrated membrane-based red LEDs are opening an avenue for flexible full color inorganic devices.

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.

Funding Information: The authors J.E., C.D. and A.K. would like to thank Jean Dussaud for his work on the MOVPE setup. V.N. would like to thank Maria Baeva for her assistance with the stretchable LED transparency measurements.J.E., C.D. and A.K. thank French National Labex GaNeX (ANR-11-LABX-0014) for MW synthesis and CL measurements. V.N. thanks the Russian Foundation for Basic Research (RFBR project no. 19-32-60040) for PDMS/MW membrane fabrication and optical measurements. I.S.M., V.N., F.M.K. thank the support from the Russian Science Foundation (grant 20-19-00256) for PDMS synthesis and electrical measurements. D.K. and A.G.N. thank Russian Foundation of Basic Research project no. 20-03-00804 for the synthesis of carbon nanotubes. F.E.K. thanks the support from the Russian Science Foundation (grant 19-79-00313) for the LED array encapsulation and membrane transfer. I.S.M., F.M.K., V.N., V.A.M., S.M., A.A.V., A.V.U., and D.A.M. thank the Ministry of Science and Higher Education of the Russian Federation (FSRM-2020-0005) for the general support. N.A. and M.T. acknowledge the financial support from the ITN Marie Curie project INDEED (grant no. 722176), by the Indo-French Centre for the Promotion of Advanced Research (IFCPAR/CEFIPRA project no. 6008-1) for MW/PDMS membrane processing and characterization. Funding Information: Funding: J.E., C.D. and A.K. thank French National Labex GaNeX (ANR-11-LABX-0014) for MW synthesis and CL measurements. V.N. thanks the Russian Foundation for Basic Research (RFBR project no. 19-32-60040) for PDMS/MW membrane fabrication and optical measurements. I.S.M., V.N., F.M.K. thank the support from the Russian Science Foundation (grant 20-19-00256) for PDMS synthesis and electrical measurements. D.K. and A.G.N. thank Russian Foundation of Basic Research project no. 20-03-00804 for the synthesis of carbon nanotubes. F.E.K. thanks the support from the Russian Science Foundation (grant 19-79-00313) for the LED array encapsulation and membrane transfer. I.S.M., F.M.K., V.N., V.A.M., S.M., A.A.V., A.V.U., and D.A.M. thank the Ministry of Science and Higher Education of the Russian Federation (FSRM-2020-0005) for the general support. N.A. and M.T. acknowledge the financial support from the ITN Marie Curie project INDEED (grant no. 722176), by the Indo-French Centre for the Promotion of Advanced Research (IFCPAR/CEFIPRA project no. 6008-1) for MW/PDMS membrane processing and characterization. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. We propose and demonstrate both flexible and stretchable blue light-emitting diodes based on core/shell InGaN/GaN quantum well microwires embedded in polydimethylsiloxane membranes with strain-insensitive transparent electrodes involving single-walled carbon nanotubes. InGaN/GaN core-shell microwires were grown by metal-organic vapor phase epitaxy, encapsulated into a polydimethylsiloxane film, and then released from the growth substrate. The fabricated free-standing membrane of light-emitting diodes with contacts of single-walled carbon nanotube films can stand up to 20% stretching while maintaining efficient operation. Membrane-based LEDs show less than 15% degradation of electroluminescence intensity after 20 cycles of stretching thus opening an avenue for highly deformable inorganic devices.

The development of THz technology and communication systems is creating demand for devices that can modulate THz beams rapidly. Here we report the design and characterisation of high-performance, broadband THz modulators based on the photo-induced transparency of carbon nanotube films. Rather than operating in the standard modulation mode, where optical excitation lowers transmission, this new class of modulators exhibits an inverted modulation mode with an enhanced transmission. Under femtosecond pulsed illumination, modulation depths reaching + 80 % were obtained simultaneously with modulation speeds of 340 GHz. The influence of the film thickness on the insertion loss, modulation speed and modulation depth was explored over a frequency range from 400 GHz to 2.6 THz. The excellent modulation depth and high modulation speed demonstrated the significant potential of carbon nanotube thin films for ultrafast THz modulators.

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.

Here we have studied the kinetics of the ethylene non-catalytic decomposition on the surface of multi-walled carbon nanotubes (MWCNTs) leading to the formation of lateral carbon deposits (LCD). Despite the comprehensive data on the gas-phase pyrolysis and a clear presence of surface impurities formed of carbon deposits, this process has not gained any proper attention. Within the temperature range studied (650–750 °C), we have found the rate of the reaction to be proportional to the MWCNT surface area and ethylene partial pressure. The activation energy of carbon deposition is close to that for the collision of two ethylene molecules to form C2H5· and C2H3· radicals. Based on the data obtained, we have proposed the radical mechanism of the formation of the deposits. High-resolution TEM, synchrotron radiation XRD, Raman spectroscopy, differential thermal analysis, temperature dependence of conductivity, and surface area measurements were used to characterize the structure and properties of the carbon-carbon composite produced. We have shown the deposition of lateral carbon to be a soft non-destructive technique for MWCNT surface functionalization allowing one to tune the properties of 3D-structured nanotube materials (e.g. arrays or aerogels). As an example, the LCD coating gradually changes the conductivity mechanism to 3D variable range hopping.

A macroporous carbon aerogel (MCA) was produced by in situ synthesis of multi-walled carbon nanotubes (CNTs) via catalytic high-temperature decomposition of ethylene over the supported Fe:Co catalyst. A three-dimensional framework of ball-shaped MCA granules was formed by chaotic interlacing of growing CNTs and mechanical strength of the granules was high enough for their promising application in heterogeneous processes, in particular, bioconversion of fatty acids. The macroporous carbon aerogel was investigated as a novel support for adsorptive immobilization of an enzyme—Thermomyces lanuginosus lipase, followed by preparation of the lipase-active heterogeneous biocatalysts. It was found that the efficient and tight adsorption of the lipase on MCA occurred due to hydrophobic interactions. The amount of the lipase adsorbed in one dense adsorptive layer was equal to 110 mg per 1 g of the carbon aerogel. The lipase adsorbed in the 1st adsorptive layer possessed the maximum activity, 700–800 U/mg. The lipase-active heterogeneous biocatalysts were studied in the periodic processes of hydrolysis of emulsified triglycerides (tributyrin), interesterification of vegetable oil with ethyl acetate, and esterification of fatty acids (butyric C4:0, capric C10:0, and stearic C18:0) with isopentanol. It was found that T. lanuginosus lipase lost significantly its enzymatic activity during adsorption on the carbon aerogel; possible causes of the negative effect of such immobilization were discussed. The specific activity of the adsorbed lipase, as well as activity and stability of the biocatalysts depended foremost on the type of the reaction performed. The maximum activities of the biocatalysts were determined to be approximately 75·103 and 2.5 U/g in tributyrin hydrolysis (aqueous media) and esterification of fatty acid (non-aqueous media), respectively. Stability of the biocatalysts was very high in the esterification reaction due to accumulation of essential water inside MCA. The lipase-active biocatalysts carried out the synthesis of isopentyl caprinate in organic solvents (hexane + diethyl ether) for several 100 h at 40 °C.

A machine learning technique, namely, support vector regression, is implemented to enhance single-walled carbon nanotube (SWCNT) thin-film performance for transparent and conducting applications. We collected a comprehensive data set describing the influence of synthesis parameters (temperature and CO2 concentration) on the equivalent sheet resistance (at 90% transmittance in the visible light range) for SWCNT films obtained by a semi-industrial aerosol (floating-catalyst) CVD with CO as a carbon source and ferrocene as a catalyst precursor. The predictive model trained on the data set shows principal applicability of the method for refining synthesis conditions toward the advanced optoelectronic performance of multiparameter processes such as nanotube growth. Further doping of the improved carbon nanotube films with HAuCl4 results in the equivalent sheet resistance of 39 Ω/□-one of the lowest values achieved so far for SWCNT films.

We propose a novel, scalable, and simple method for aerosol doping of single-walled carbon nanotube (SWCNT) films. This method is based on aerosolization of a dopant solution (HAuCl4 in ethanol) and time-controlled deposition of uniform aerosol particles on the nanotube film surface. The approach developed allows fine-tuning of the SWCNT work function in the range of 4.45 eV (for pristine nanotubes) to 5.46 eV, controllably varying the sheet resistance of the films from 79 to 3.2 Ω/□ for the SWCNT films with 50% transmittance (at 550 nm). This opens a new avenue for traditional and flexible optoelectronics: both to replace existing indium-tin oxide electrodes and to develop novel applications of the highly conductive transparent films.

We present the simple procedure of the vapor-phase bromination of multiwall carbon nanotubes (MWNTs) at moderate temperatures. MWNTs with average diameter9±3 nm were treated with Br2vapors at 250°C to produce Br-functionalized product. Transmission electron microscopy analysis was used to prove low damage of MWNT walls during bromination. X-ray photoelectron spectroscopy (XPS) and differential thermal analysis (DTA) were used to investigate chemical composition of the surface of initial and brominated nanotubes. The experimental results show that the structure of MWNTs is not affected by the bromination process and the total amount of Br-containing surface functions reaches 2.5 wt. %. Electrophysical properties of initial and brominated MWNTs were investigated showing decrease of conductivity for functionalized sample. Possible mechanism of the vapor-phase bromination via surface defects and oxygen-containing functional groups was proposed according to data obtained. Additional experiments with bromination of annealed low-defected MWNTs were performed giving Br content a low as 0.75 wt. % proving this hypothesis.

Coagulation technique was applied for preparation of multiwall carbon nanotube- (MWNT-)containing polystyrene (PSt) composite materials with different MWNT loading (0.5–10 wt.%). Scanning and transmission electron microscopies were used for investigation of the morphology and structure of produced composites. It was shown that synthesis of MWNT/PSt composites using coagulation technique allows one to obtain high dispersion degree of MWNT in the polymer matrix. According to microscopy data, composite powder consists of the polystyrene matrix forming spherical particles with diameter ca. 100–200 nm, and the surface of MWNT is strongly wetted by the polymer forming thin layer with 5–10 nm thickness. Electrical conductivity of MWNT/PSt composites was investigated using a four-probe technique. Observed electrical percolation threshold of composite materials is near to 10 wt.%, mainly due to the insulating polymer layer deposited on the surface of nanotubes. Electromagnetic response of prepared materials was investigated in broadband region (0.01–4 and 26–36 GHz). It was found that MWNT/PSt composites are almost radiotransparent for low frequency region and possess high absorbance of EM radiation at higher frequencies.