Nowadays, carbon nanotubes have a lot of applications in daily life, being applied in the fabrication of cellphones, computers, nanotransistors, among many others. Currently, their new applications in biotechnology area are in research, in particular in order to find new biosensors with fluorescent properties applying on the basis of multi-wall carbon nanotubes (MWCNTs). In this work, the obtaining of carbon nanoparticles having fluorescent properties via spray pyrolysis is presented. Synthesis, properties, structural peculiarities, and applications of nanobuds and related nanostructures are discussed. MWCNTs, decorated with strontium aluminate SrAl12O19 and doped with rare-earth elements, were synthetized from distinct organic precursors and the corresponding metal oxides. The metal oxides used were Samarium (Sm), Europium (Eu), Neodymium (Nd), Lanthanum (La), Cerium (Ce) and some their combinations.The synthesis was carried out on the surface of optical fibres to obtain a uniform growth of forest-like MWCNTs, adding to metal oxide nanoparticles to their surface. The preparation of composites was carried out by spray pyrolysis techniques in dry nitrogen atmosphere in the temperature range from 780 to 850°C. The formed products were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), FTIR spectroscopy, Raman spectroscopy and UV/visible spectroscopies. The analysis of the obtained data shows that the deposited nanoparticles are in the range of size 20-60 nm being uniformly distributed on the surface of MWCNTs. The samples, obtained at different temperatures and with doping metal oxides added to SrAl12O19, show different fluorescence behavior. The best results were observed with lanthanum oxide as a dopant. Possible applications as persistently luminescent phosphors for the formed MWCNTs-supported luminescent materials are proposed.

Background: Methods for obtaining the hybrids of multi-wall carbon nanotubes (MWCNTs) and rare earths are in progress. Such composites may possess luminescent properties, which could be of interest for various areas, in particular, medicine (imaging), engineering (fluorescent polymers, LED and relative materials), among other applications. Lanthanide oxides, additionally, can serve as catalysts for MWCNTs formation and catalysts of several organic reactions. Objective: The goal of this work is to obtain the composites of MWCNTs with strontium aluminate, doped with several lanthanides (Eu, Ce, La, Nd, and Sm), via the spray pyrolysis method and to study the properties of the formed hybrids. Methods: The spray pyrolysis method in the temperature range from 780 to 850oC, starting from toluene as a carbon source and ferrocene as a catalyst precursor. SrAl12O19 doped with rare-earths were added to carbon matter in the ultrasonic field. Methods: Among various structures, the forest-like nanostructures have been observed in some cases. The formed coated carbon nanotubes possess fluorescent properties due to the attachment of lanthanide- doped ceramic compound (SrAl12O19) to their surface, allowing the emission control for each dopant: yellow (Nd2O3), blue (Eu2O3 and Sm2O3), intense orange (La2O3), light orange (Ce2O3). Conclusion: MWCNTs decorated with strontium aluminate (SrAl12O19), doped with a series of lanthanide oxides (Nd2O3, Eu2O3, La2O3, Ce2O3, Sm2O3), were obtained by the spray pyrolysis technique on the surface of optical fibers. Lanthanum- and cerium-containing coatings were found to show a better deposition on the MWCNTs surface, exhibiting uniform coating. MWCNTs, coated with Nd-, Ce-, and Eu-doped SrAl12O19 were shown to reveal the best conductive properties.

A nanomaterial that attracts the attention in a variety of research areas is multiwall carbon nanotubes (MWCNTs), due to their good mechanical proprieties, and high electrical and thermal conductivity. For this reason, the preparation of three-dimensional (3D) structures from them draws interest because it opens new horizons to produce materials with novel properties and useful applications. In this investigation the synthesis of 3D nanotube carbon (nanoforest type) functionalized with nanoparticles of silver, aluminum, and iron was studied. A 3D structure was produced in the form of aligned microchannels. The functionalization of carbon nanotubes with nanoparticles of silver, aluminum or iron during the synthesis process of carbon nanotubes, was carried out through spray-pyrolysis with different synthesis time and solution concentration. The results were characterized through microscopy SEM, TEM and Raman’s spectroscopy.

Some potential applications of the nanoribbons and nanorods occur in the medical field, using gold nanoribbon therapies against cancer cells because they have absorption in the near infrared region. In this paper, the nanoribbons were obtained by physical-chemical method based on multilayer carbon nanotubes functionalized with carboxylic radical groups (-COOH). The obtained material was characterized by Scanning Transmission Electron Microscopy (STEM) and Infrared Spectroscopy (FTIR). The obtained nanoribbons have a diameter of 320 nm with preferably 126° angle in their morphology.