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Single-walled carbon nanotubes (SWCNTs) demonstrate unique properties of both electrical and thermal conductivity, but at the moment of producing a network composed of multiple nanotubes, these values sharply decrease. It is associated with the presence of defects in the nanotube network structure, as well as with the dissipation phenomena at the junctions between SWCNTs. One of the methods to alleviate this problem is doping. In our study, we obtained a film made of high-quality SWCNTs doped with three types of iodonium salts: Barluenga’s reagent (bispyridineiodonium tetrafluoroborate, IPy2BF4), pyridine iodine monochloride (IPyCl) and diphenyliodonium chloride (DPIC). We recorded a significant improvement in electrical properties after doping with IPy2BF4 and IPyCl, by as much as 224% and 322%, respectively. What is more, we noted improvement in thermal conductivity, which amounted to over 50% when the material was doped with IPyCl. Our research indicates that permanent doping of CNT-based ensembles is possible with iodonium salts. The process significantly improves electrical conductivity, and the compounds themselves are more convenient to work with rather than when other halogen-based dopants are used commonly for this purpose.

A facile procedure for the synthesis of ultra-fine silicon nanoparticles without the need for a Schlenk vacuum line is presented. The process consists of the production of a (HSiO 1.5 ) n sol–gel precursor based on the polycondensation of low-cost trichlorosilane (HSiCl 3 ), followed by its annealing and etching. The obtained materials were thoroughly characterized after each preparation step by electron microscopy, Fourier transform and Raman spectroscopy, X-ray dispersion spectroscopy, diffraction methods and photoluminescence spectroscopy. The data confirm the formation of ultra-fine silicon nanoparticles with controllable average diameters between 1 and 5 nm depending on the etching time.

There is a growing demand for nanoparticles coated with graphene due their promise in various applications such as batteries and supercapacitors, sorbents, and biomedical applications. A good example is Si where its combination with carbon is considered important for electronics and energy applications, such as lithium ion batteries, polymer based composites and even bio-medical applications. In this study, we aim to develop a very simple chemical vapor deposition approach to form graphitized Si nanoparticles in which ethanol serves as the C feedstock. This differs from other CVD approaches which tend to use a gaseous hydrocarbon (e.g. CH 4 ) as the carbon feedstock. The use of ethanol in which Ar is simply bubbled through liquid ethanol leads to a simpler and cheaper approach. Moreover, in conventional CVD, often an oxidant (e.g. CO 2 ) is added to aid graphitization and minimize the formation of SiC at the Si surface. Ethanol provides a source of O which serves as an inbuilt oxidizer to aid graphitization and limit the formation of SiC. The simple synthesis approach allows one to tailor the number of graphene layers coating the Si nanoparticles through the three main synthesis parameters of ethanol supply, temperature and reaction time. Moreover, using ethanol as the precursor, lower graphitization temperatures than for methane can be used.

Graphenic materials have been produced from thermally treated highly metamorphosed carbon material – anthracite using two different methods: (1) the improved Hummers method followed by thermal redu...

Three-dimensional (3D) nanostructured graphene can be used as a replacement or enrichment material. This review presents the types of 3D graphene developed thus far, for example, nanoshells, encapsulates, graphene foams, aerogels and hydrogels, their properties and the methods by which to obtain them, such as chemical vapour deposition, the hydrothermal method or by sugar-blowing production. The review also covers areas in which 3D graphene foam has been exploited for application such as energy, electronic, biomedical and environmental protection as well as the latest developments.

To synthesize graphene by chemical vapor deposition (CVD) both in large area and with uniform layer number directly over Si/SiOx has proven challenging. The use of catalytically active metal substrates, in particular Cu, has shown far greater success and therefore is popular. That said, for electronics applications it requires a transfer procedure, which tends to damage and contaminate the graphene. Thus, the direct fabrication of uniform graphene on Si/SiOx remains attractive. Here we show a facile confinement CVD approach in which we simply “sandwich” two Si wafers with their oxide faces in contact to form uniform monolayer graphene. A thorough examination of the material reveals it comprises faceted grains despite initially nucleating as round islands. Upon clustering, they facet to minimize their energy. This behavior leads to faceting in polygons, as the system aims to ideally form hexagons, the lowest energy form, much like the hexagonal cells in a beehive, which requires the minimum wax. This proce...

Carbon nanotubes (CNTs) have recently emerged as one of the most promising structures for thermoelectrics (TE). As compared with typical thermoelectric materials, CNTs can be made from almost any carbon-bearing precursor, and so at present thousands of tonnes of them are produced annually at every corner of the world. In this work, we synthesized multi-walled CNTs (MWCNTs) and doped them with heteroatoms of nitrogen, boron or phosphorus to tune their thermoelectric performance. The research showed that MWCNTs doped with nitrogen or boron had improved thermoelectric properties by up to three orders of magnitude as compared with the undoped material. Because of the different modes of charge transport by electrons and holes, respectively, they could be used to construct functional thermoelectric modules.

The various forms of carbon nanostructures are providing extraordinary new opportunities that can revolutionize the way gas sensors, electrochemical sensors and biosensors are engineered. The great potential of carbon nanostructures as a sensing platform is exciting due to their unique electrical and chemical properties, highly scalable, biocompatible and particularly interesting due to the almost infinite possibility of functionalization with a wide variety of inorganic nanostructured materials and biomolecules. This opens a whole new pallet of specificity into sensors that can be extremely sensitive, durable and that can be incorporated into the ongoing new generation of wearable technology. Within this context, carbon-based nanostructures are amongst the most promising structures to be incorporated in a multi-functional platform for sensing. The present review discusses the various 1D, 2D and 3D carbon nanostructure forms incorporated into different sensor types as well as the novel functionalization approaches that allow such multi-functionality.

The large specific surface area and strong adsorption ability of graphene oxide and its derivates such as partially or fully reduced graphene oxide are attractive for gas-sensing applications. Such materials are also easy to work with and are economically attractive and are thus suited to large scale fabrication. Here we compare graphene oxide with two partially reduced graphene oxide materials. In the first, ascorbic acid is used as a weak reducer and in the second, we demonstrate a new thiolation/reduction route which can also partially reduce graphene oxide and in addition provide thiol groups at the surface. We then compare the three materials for use in a simple drop-cast sensor system. The signal profile data from the three different sensors vary in shape and intensity as well as response and recovery times for the two different analytes investigated. The data suggests these parameters could be used as an array system to discriminate between analytes.