Recent trends in the area of catalytic applications of metal–organic framework (MOF)-derived nanocarbons are covered. These highly porous nanostructures, convenient for the green chemistry processes, are generally formed by the direct carbonization of a variety of MOF, mainly MOF-5, ZIF-8, ZIF-67, UiO-66-NH2, MIL-101-NH2 at 700–1000 °C in argon or nitrogen flow. Differences between conventional porous carbons and MOF-derived carbons are in pore volumes, surface area, and presence of ad-atoms. The morphology of the MOF-derived nanocarbons can be adjustable with uniform dopant distribution. Resulting nanocarbons are widely applied in heterogeneous catalysis, photocatalysis and are very promising as electrocatalysts, having excellent performance in oxygen evolution reaction, oxygen reduction reaction, and hydrogen evolution reaction. Catalytic applications for environmental purposes are also discussed. Good catalytic performance is related with highly dispersed heteroatoms, density of catalytic active sites, controllable porosity, and high surface area. Opportunities for further research are indicated, in particular, the creation of low pH-stable electrocatalysts and novel strategies for the preparation of 1÷3D single-atom catalysts.

Metal–organic frameworks (MOFs) possess tuneable properties and a variety of important applications in the areas of catalysis, adsorption, gas storage, and separation, among others. Herein, recent computational studies by density functional theory (DFT) applied for simulations of MOF structure and complex architecture determination, prediction of properties, and computational characterization, including large-scale screening and geometrical properties of hypothetical MOFs, diffusion and adsorption processes in MOFs, are reviewed. DFT calculations have been applied in the MOF area to study chemical stability; mechanical, photophysical, optical, and magnetic properties; photoluminescence; porosity; and semiconductor or metallic character. The prediction of MOF analogs with open-metal sites, studies of chemical bonding and the prediction of energies by quantum mechanics allows reducing experimental efforts in the creation of MOF/polymer membranes, adsorbents for CO2 uptake, separation of C2H2/CH4, C2H2/CO2, and inert gases, radionuclides sequestration, and water adsorption, as well as other promising advances. For the MOF-derived carbons, a lack of profound DFT investigations is currently observed, being mainly restricted to the electrocatalysis area (nitrogen reduction reaction, oxygen evolution reaction, and hydrogen evolution reaction), resulting applications in batteries and other storage devices, CO2 sequestration, and absorbance of organic substances.

Toroidal (ring-like) structures are common in organic chemistry, but at the nanoscale level, the inorganic nanorings and nanotori are limited and represented mainly by carbon, several p- and noble metals (Ag, Au, Al, and Au/Co/Au), metal and nonmetal oxides (ZnO, MoO2, Fe2O3, and SiO2), hydroxides (Co(OH)2), and salts (PbI2 and metal selenides), and some combinations of carbon nanotori with fullerenes and carbon chains, as well as doped nanorings, are known. The nanotori are closely related to ball-type nanostructures as nano-onions, nanoballs, and nanospheres. Despite their relative low existence, they possess several useful properties and respective applications as isolators, sensors, optoelectronics, as traps for atoms and ions, and counterparts in lubricants, thus causing a certain interest in their development. The properties of nanotori have been studied mainly by DFT calculations. Several nanorings possess stabilities up to 3000 K before unfolding, multiresonant properties and magneto–optical activity, paramagnetism, and ferromagnetism. The carbon nanorings are studied considerably better, being compared with other compounds. This review summarizes the state of the art of all available inorganic toroidal nanostructures, believing that a considerable higher number of inorganic systems might be prepared in this form, taking into account their unusual properties.

To free ourselves from the use of fossil fuels that are highly polluting, life-threatening and not easily regenerated, new technologies are being developed to obtain alternative energy sources more efficiently. Among these technologies, there is the option to improve the performance of solid oxide fuel cells (SOFCs) to make them highly energy efficient. Solid oxide fuel cells (SOFCs) have attracted much attention because they are environmentally benign, sustainable, generate low emissions and have relative low cost. However, conventional SOFCs with yttria-stabilized zirconia (YSZ) electrolyte require high operating temperatures (800-1000°C), which often lead to material degradation problems. Given that the greatest disadvantage of SOFCs is their high operating temperature, samples of CeO2 were synthesized by spray pyrolysis method and doped with Sm2O3 and Eu2O3 to improve the ionic conductivity of the electrolyte so that it can operate at lower temperatures without losing its efficiency. The samples were analyzed using SEM, EDS, TEM. Further research will be made by small angle DRX, AFM, EIS and a prototype will be built to test the working temperature of the electrolyte.

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.

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.

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.

According to the reports of Z.E. Horvath et al [1] and Liu Yun-quan et al [5], carbon nanotubes can be synthesized by spray pyrolysis from different carbon sources (n-pentane, n-hexane, n-heptane, cyclohexane, toluene and acrylonitrile) and several metallocene catalysts (ferrocene, cobaltocene and nickelocene). This paper describes two different existing methods for growth of carbon nanotubes and the influence of applied parameters (oven temperature, synthesis time, catalyst concentration, carrier gas flow and solution flow) on the CNT's morphology. Also, a possible influence of number of carbons in carbon sources and structures of their compounds (linear or aromatic) on properties of formed carbon nanotubes. Transmission Electron Microscopy (TEM), Infrared Spectroscopy (FTIR) and Raman spectroscopy were applied for characterization of obtained materials.

Contemporary methods for dispersion of carbon nanotubes in water and non-aqueous media are discussed. Main attention is paid to ultrasonic, plasma techniques and other physical techniques, as well as to the use of surfactants, functionalizing and debundling agents of distinct nature (elemental substances, metal and organic salts, mineral and organic acids, oxides, inorganic and organic peroxides, organic sulfonates, polymers, dyes, natural products, biomolecules, and coordination compounds).

Nanocomposites of polysaccharide matrices, chitosan-starch and carboxymethyl cellulose-starch reinforced with graphene oxide and graphene grafted with keratin were developed. Composites films had been prepared for the casting/solvent evaporation method. The nanocomposites of chitosan/starch matrix improved substantially their mechanical properties with respect to the film without reinforcing, obtaining an increase of 929 % in the storage modulus (E’ 35°C) with only 0.5 wt% of graphene oxide and outstanding increments in E’ at 150°C and 200°C when keratin grafted graphene oxide is incorporated (0.1 wt%). In contrast, the graphene oxide incorporated into the carboxymethyl cellulose-starch matrix tends to decrease the stiffness of the film behaving in opposite way to nanocomposite of chitosan/starch matrix.

Material like PET {polyethylene terephthalate (C10H8O4)n} are usually thrown away present in glasses of refreshments, water bottles between others which are hard to be degraded. However, this material can be recycled and used to acquire nanostructures. During this investigation the objective was to obtain nanoparticles and carbon based nanostructures from the polymer type PET by means of microwave irradiation at the temperature of 260°C at normal pressure and at 600 psi in the presence of acids, ethylene glycol and by means of calcinations. The obtained nanoparticles of ultrananocrystalline diamonds were studied by means of scanning electron microscopy (SEM), high-resolution transmission electron microscopy (TEM), and Raman spectroscopy.

Methods of “green” synthesis of nanoparticles of elemental iron (zero-valent iron, NZVI), its oxides and hydroxides using natural products are reviewed. In particular, the use of biological agents such as extracts of various plants, tea, soya, table sugar and glucose, as reductants and as capping agents is shown. The techniques involved are simple, environmentally friendly and generally one-pot processes. Water disinfection using iron nanomaterials against viruses and bacteria is also examined.

The functionalization of single wall carbon nanotubes (SWCNT) with arenediazonium salts, formed in situ from anilines as dimethyl-5-aminoisophthalate, sulfanilamide and p-anisidine, using the environmentally solvent urea. The functionalized SWNTs were then characterized using spectroscopic and microscopic methods along with thermogravimetric analysis (TGA). According to enhance solubility in solvents after that introduce them into the industrial processes. The molecules added appear on the nanotubes like chemical anchors.

Elemental bismuth nanoparticles and nanotubes were obtained via microwave hydrothermal synthesis starting from bismuth oxide (Bi2O3) in the range of temperatures 200-220oC for 10-45 min. The formed nanostructures were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Relationship between reaction parameters and shape of the formed nanostructures is discussed.

A highly efficient one-step technique was developed in order to obtain long and aligned carbon nanotubes with or without Fe filling. The aligned carbon nanotubes (CNTs) were synthesized by heating ferrocene Fe(C5H5)2 using microwave (MW) irradiation. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) were used to study the growth process of the aligned multi-layer carbon nanotubes. It was found that CNTs have a metal particle at the tip of each tube. This carbon nanostructures promise to become important in fuel cells and in nanoscale engineering of other systems.

This work is devoted to microwave heating of graphite, sucrose, calcined sucrose, and a mixture of graphite with sucrose to produce carbon nanotubes (CNT's). The samples were submitted to microwave radiation (power 800W, frequency 2.45 GHz) in air and high vacuum (10−5Torr) for 30 – 60 min. The oven temperature was approximately 1200°C. After vaporization the condensed material was collected on various fused silica targets (different morphologies were used). The samples were found to contain a significant proportion of nanotubes, nanoparticles and fibers (1-2.8 micrometers), which appeared to be highly graphitized and helical structured. After deposition, the morphology of carbon nanotubes was studied with SEM, TEM and AFM techniques. It was observed that multi-walled nanotubes (MWNT's) were produced by this method. The morphology of fused silicon based substrates (SiO2, SiC) was studied as an important factor for the growth of carbon nanotubes. Many aspects as the size and shape of the obtained nanotubes on different substrates (porous and non-porous fused silicon substrates) were achieved, as well as the concentration of them across the substrate and other properties.

This work is devoted to microwave heating of graphite for studying the processing of carbon nanotubes (CNTs) by graphite vaporization. We have applied heating by microwaves (MW) (power 800W, frequency 2.45 GHz) in air at 20–90 min. The oven temperature was approximately 1200°C. The condensed material was collected on a fused silica target. After deposition, the morphology of carbon nanotubes was studied by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and Transmission Electron Microscopy (TEM). The samples were found to contain nanotubes, nanoparticles and fibers (at 1.30–2.80 micrometers to 6–11 micrometers) which appeared to be highly graphitized. It was observed that multi-walled nanotubes (MWNT's) were produced by this method.