11 research outputs found
Light-induced sulfur transport inside single-walled carbon nanotubes
This article belongs to the Section 2D and Carbon Nanomaterials.Filling of single-walled carbon nanotubes (SWCNTs) and extraction of the encapsulated species from their cavities are perspective treatments for tuning the functional properties of SWCNT-based materials. Here, we have investigated sulfur-modified SWCNTs synthesized by the ampoule method. The morphology and chemical states of carbon and sulfur were analyzed by transmission electron microscopy, Raman scattering, thermogravimetric analysis, X-ray photoelectron and near-edge X-ray absorption fine structure spectroscopies. Successful encapsulation of sulfur inside SWCNTs cavities was demonstrated. The peculiarities of interactions of SWCNTs with encapsulated and external sulfur species were analyzed in details. In particular, the donorâacceptor interaction between encapsulated sulfur and host SWCNT is experimentally demonstrated. The sulfur-filled SWCNTs were continuously irradiated in situ with polychromatic photon beam of high intensity. Comparison of X-ray spectra of the samples before and after the treatment revealed sulfur transport from the interior to the surface of SWCNTs bundles, in particular extraction of sulfur from the SWCNT cavity. These results show that the moderate heating of filled nanotubes could be used to de-encapsulate the guest species tuning the local composition, and hence, the functional properties of SWCNT-based materials.This work was supported by the Russian Science Foundation (Project 18-72-00017), the bilateral Program âRussian-Germany Laboratory at BESSY IIâ in the part of XPS and C K-edge NEXAFS measurements, and shared research center SSTRC on the basis of the Novosibirsk VEPP-4 - VEPP-2000 complex at BINP SB RAS, using equipment supported by project RFMEFI62119X0022 in the part of S K-edge NEXAFS measurements. R.A. acknowledges the support from the Spanish Ministerio de Economia y Competitividad (MAT2016-79776-P, AEI/FEDER, EU), from the European Unionâs Horizon 2020 programme under the project âESTEEM3â (823717) and from the Government of Aragon and the European Social Fund under the project âConstruyendo Europa desde Aragonâ 2014â2020 (grant number E13_17R, FEDER, EU).Peer reviewe
Study of cytotoxicity performance of carbon nanohorns by method of spin probes
The effects of as-produced and treated by HNO3(3M) carbon nanohorns on the microviscosity of rat erythrocyte membranes and the viscosity of the water-containing plasma protein matrix were investigated by the method of spin probes. Addition of nanohorns at the concentration of 100âÎŒg/ml to a suspension of erythrocytes led to an increase in membrane microviscosity during 4âh (about 60% effect). In addition, it was shown that nanohorns also induced an increased polarity of the microenvironment for lipophilic probes in the outer layer of membrane phospholipids, as well as disorders in erythrocytes membranes. Addition of nanohorns to plasma led to a little decrease in the viscosity of water and protein matrix, apparently, due to its partial destruction, impacting especially albumin. Pristine and treated by HNO3(3M) acid nanohorns was found more cytotoxic than nanoparticles of oxidized graphene, and significantly less than carbon nanotubes, which are known to dramatically increase the microviscosity of the membranes of erythrocytes and disrupt their integrity
Functional and Elemental Composition of Humic Acids of Sapropels of the River Obâs Left Bank of Khmao-Yugra
Role of interface interactions in the sensitivity of sulfur-modified single-walled carbon nanotubes for nitrogen dioxide gas sensing
Single-walled carbon nanotubes (SWCNTs) possess the unique ability to tune their functional properties by modifying the outer surface or interior space. Using the same modifier â sulfur, we demonstrate a difference in sensing properties of coated and filled single-walled carbon nanotubes to gaseous nitrogen dioxide. A comprehensive investigation of materials by transmission electron microscopy, X-ray photoelectron spectroscopy, density functional theory, and kinetics simulation led to an in-depth understanding of the factors influencing the sensor response of sulfur-modified SWCNTs, such as the role of surface and volumetric processes and interface effects. The sulfur-filled nanotubes with sulfur coating showed an outstanding sensitivity to detect nitrogen dioxide over a range from 1 ppb to 10 ppm due to the involvement of sulfur species in charge transfer between nanotubes and adsorbed molecules. Our data create a platform for the development of sensitive and reversible gas sensors using nanotube-based networks.The research was supported by the Ministry of Science and Higher Education of the Russian Federation (No. 121031700314-5). The authors thank the Helmholtz-Zentrum Berlin fĂŒr Materialien und Energie for allocation of a beamtime and support within bilateral program âRussian-German Laboratory at BESSY IIâ. O.V. Sedelnikova acknowledges the Scholarship of the President of the Russian Federation (SP-1593.2021.1). The work on the fabrication of SWCNT films was supported by the Russian Science Foundation (grant 21-73-00229). V.O. Koroteev acknowledges financial support by the Spanish Ministry of Economy and Competitiveness (MINECO) within the Maria de Maeztu Units of Excellence Programme â MDM-2016-0618. A.A. Makarova acknowledges BMBF (grant no. 05K19KER). The EEL-SPIM inalysis was conducted at the Laboratorio de Microscopias Avanzadas (LMA) at the Instituto de Nanociencia de Aragon (INA) - Universidad de Zaragoza (Spain). R. Arenal acknowledges the support from the Spanish MICINN (PID2019-104739GB-100/AEI/10.13039/501100011033), from the European Union's Horizon 2020 programme under the project âESTEEM3â (823717) and from the Government of Aragon (grant number E13_20R).Peer reviewe
Effect of Titanium and Molybdenum Cover on the Surface Restructuration of Diamond Single Crystal during Annealing
Diamond is an important material for electrical and electronic devices. Because the diamond is in contact with the metal in these applications, it becomes necessary to study the metalâdiamond interaction and the structure of the interface, in particular, at elevated temperatures. In this work, we study the interaction of the (100) and (111) surfaces of a synthetic diamond single crystal with spattered titanium and molybdenum films. Atomic force microscopy reveals a uniform coating of titanium and the formation of flattened molybdenum nanoparticles. A thin titanium film is completely oxidized upon contact with air and passes from the oxidized state to the carbide state upon annealing in an ultrahigh vacuum at 800 °C. Molybdenum interacts with the (111) diamond surface already at 500 °C, which leads to the carbidization of its nanoparticles and catalytic graphitization of the diamond surface. This process is much slower on the (100) diamond surface; sp2-hybridized carbon is formed on the diamond and the top of molybdenum carbide nanoparticles, only when the annealing temperature is raised to 800 °C. The conductivity of the resulting sample is improved when compared to the Ti-coated diamond substrates and the Mo-coated (111) substrate annealed at 800 °C. The presented results could be useful for the development of graphene-on-diamond electronics
Enhancement of Volumetric Capacitance of Binder-Free Single-Walled Carbon Nanotube Film via Fluorination
Robust electrode materials without the addition of binders allow increasing efficiency of electrical storage devices. We demonstrate the fabrication of binder-free electrodes from modified single-walled carbon nanotubes (SWCNTs) for electrochemical double-layer capacitors (EDLCs). Modification of SWCNTs included a sonication in 1,2-dichlorobenzene and/or fluorination with gaseous BrF3 at room temperature. The sonication caused the shortening of SWCNTs and the splitting of their bundles. As a result, the film prepared from such SWCNTs had a higher density and attached a larger amount of fluorine as compared to the film from non-sonicated SWCNTs. In EDLCs with 1M H2SO4 electrolyte, the fluorinated films were gradually defluorinated, which lead to an increase of the specific capacitance by 2.5â4 times in comparison with the initial values. Although the highest gravimetric capacitance (29 F gâ1 at 100 mV sâ1) was observed for the binder-free film from non-modified SWCNT, the fluorinated film from the sonicated SWCNTs had an enhanced volumetric capacitance (44 F cmâ3 at 100 mV sâ1). Initial SWCNT films and defluorinated films showed stable work in EDLCs during several thousand cycles
Magnetic Properties of 1D IronâSulfur Compounds Formed Inside SingleâWalled Carbon Nanotubes
Charge Photogeneration in Composites of Fluorinated Carbon Nanotubes and Semiconducting Polymer P3HT
Creative precarity? Young fashion designers as entrepreneurs in Russia
This article explores the careers of young fashion designers as entrepreneurs in Russia. It discusses entrepreneurial experiences and labour practices of fashion designers in the context of precarity: that is, the structural conditions characterized by a lack of social, economic and emotional security caused by a shift of responsibilities for the labour market from the state to the citizens. The article takes the perspective of designersâ agency and answers the question of how young fashion entrepreneurs deal with such structural conditions using state support, community support, organizational practices and emotional management. The article also focuses on creative labour in the broader context of the circumstances of a creative class in an authoritarian state. We argue that in todayâs Russia, the discourse on the creative class is perhaps more important than the discourse on precarity, since belonging to the creative class is a source of political identity for fashion designers. The issue of precarity, then, can become a further basis for solidarity and political action. The research draws from 21 in-depth interviews with fashion designers and experts conducted in the cities of Moscow, St. Petersburg and Novosibirsk between 2015 and 2016.</p