B. P. Tarasov

New molecular complexes of fullerenes C60 and C70 with tetraphenylporphyrins [M(tpp)], in which M=H2, Mn, Co, Cu, Zn, and FeCl.

New molecular complexes of fullerenes C60 and C70 with tetraphenylporphyrins [M(tpp)] in which M-H2, MnII, CoII, CuII, ZnII and Fe(III)Cl, have been synthesised. Crystal structures of two C60 complexes with H2TPP, which differ only in the number of benzene solvated molecules, and C60 and C70 complexes with [Cu(tpp)] have been studied. The fullerene molecules form a honeycomb motif in H2TPP.2C60. 3C6H6, puckered graphite-like layers in H2TPP.2C60.4C6H6, zigzag chains in [Cu(tpp)].C70.1.5C7H8.0.5C2HCl3 and columns in [Cu(tpp)]2.C60. H2TPP has van der Waals contacts with C60 through nitrogen atoms and phenyl groups. Copper atoms of the [Cu(tpp)] molecules are weakly coordinated with C70, but form no shortened contacts with C60. The formation of molecular complexes with fullerenes affects the ESR spectra of [M(tpp)] (M = Mn, Co and Cu). [Mn(tpp)] in the complex with C70 lowers its spin state from S = 5/2 to S = 1/2, whereas [Co(tpp)] and [Cu(tpp)] change the constants of hyperfine interaction. ESR, IR, UV-visible and X-ray photoelectron spectroscopic data show no noticeable charge transfer from the porphyrinate to the fullerene molecules.

The prospects for using of carbon nanomaterials as hydrogen storage systems

Abstract An analysis of the literature data evidences that carbon nanomaterials (CNMs) can sorb hydrogen in the amount exceeding the values required for H 2 storage mobile systems. It allows to hope for the possibility of using CNMs (if they are available) in the hydrogen storage systems. This paper shows the possibility of the use of a method for salting out fullerenes from their solutions in hydrocarbons and presents the technological chain for the fast and cheap isolation and separation of fullerene fraction. The proposed method can be of help in speeding-up the problem solution towards the mass use of carbon nanomaterials for hydrogen storage.

Hydrogen in fullerites

The peculiar kind of fullerene molecule structure is also reflected in the crystal structure of fullerites. The cubic lattices of metal fullerides and hydrofullerenes behave similarly to the cubic lattices of different metals and alloys. They form interstitial solid solutions when impurity elements are distributed in octahedral and tetrahedral interstitial sites. By replacement of C60 and C70 molecules in lattice sites they make up substitution solid solutions. Forming exo- and endohedral compounds, the fullerene molecules, located in sites of the crystal lattice, can modify greatly the crystal properties with no change of crystalline structure. Some peculiarities of fullerite crystalline structures will be discussed in the present paper.

Synthesis of carbon nanostructures by arc evaporation of graphite rods with Co-Ni and YNi2 catalysts

Yields of single-walled carbon nanotubes (SWNTs) produced from electric arc evaporation of graphite electrodes with 3Co/Ni and YNi2 catalysts differ substantially. For instance, with YNi2 catalyst, the SWNT yield is ∼30–50 wt.% in ‘collar’ soot and ∼10–15 wt.% in ‘wall’ soot, while with 3Co/Ni catalyst, the yields are ∼15–20 wt.% and 2–3 wt.%, respectively. According to Raman spectroscopy data, the average dimension of SWNTs is ∼1.2 nm for 3Co/Ni and ∼1.4 nm for YNi2 catalyst. Optimum conditions for synthesis also differ for catalysts compared; namely, for 3Co/Ni: current intensity is 93 A, helium pressure is 650 Torr, the electrode gap is 2.5–3 mm; for YNi2: current intensity is 98 A, helium pressure is 500 Torr, the electrode gap is 1–2 mm.

Preparation and properties of hydrogen-storage composites in the MgH2-C system

The hydriding properties of magnesium have been studied at temperatures from 670 to 720 K and pressures from 19 to 55 MPa. The results suggest that the hydrogen pressure and hydrogen absorption/desorption cycles influence the nucleation process in the Mg-H2 system. Using mechanical activation of MgH2 + graphite and MgH2 + graphene nanofiber (GNF) mixtures, we have prepared MgH2/graphite and MgH2/NGF composites. Investigation of their hydriding properties has shown that mechanical activation markedly accelerates hydrogen sorption/desorption processes and reduces the thermal stability of the material compared to unmilled magnesium hydride. The mechanisms of hydrogen desorption from the composites in different stages of their thermal decomposition are analyzed.

Deuterofullerene C60D24 studied by XRD, IR and XPS

Abstract The deuterofullerene C60D24 was prepared from the solid C60 and was characterised by means of XRD, IR and XPS. The C60D24 was found to be a polycrystalline powder with a FCC lattice and a=14.55 A. Deuterium thermal desorption from C60D24 leads to a reversible formation of fullerene. However, the distances between the C60 molecules become significantly longer compared to the initial fullerite.

Problem of Hydrogen Storage and Prospective Uses of Hydrides for Hydrogen Accumulation

Merits and demerits of existing methods of hydrogen storage are discussed. Special attention is given a metal hydride technology based on the ability of metals, intermetallic compounds, and alloys for reversible reaction with hydrogen. It is noted that the basic advantages of metal hydrides are a high volumetric hydrogen content, operational safety, technological flexibility, and low power inputs on hydrogen absorption and desorption.

Platinum nanoparticles on carbon nanomaterials with graphene structure as hydrogenation catalysts

Carbon nanomaterials with graphene structure (single- and multiwall nanotubes and nanofibers) after oxidizing by a mixture of sulfuric and nitric acids and presumable introducing of carboxyl groups can be used as carrying agents of hydrogenation catalysts. Platinum in a concentration which should not exceed 10 wt % can be fixed using H2PtCl6 as a precursor in presence of an organic base. Catalysts based on these nanomaterials with the average size of platinum particles 6–8 nm exceed in activity the Pt/C catalyst with the size of platinum particles 65–70 nm, but are inferior to catalysts based on fullerene black with the average size of platinum particles 3–4 nm.

Hydrogen absorption and electrocatalytic properties of ultrafine LaNi5 powders

Abstract The different conditions of milling LaNi 5 have been investigated. The hydrogen absorption characteristics and electrocatalytic properties of the ultrafine powders obtained are described and discussed. An anomalously high value of the exchange current in the reaction of hydrogen cathode deposition for some ultrafine powders has been observed.

Synthesis of graphene-like materials by graphite oxide reduction

Graphene-like materials were produced by the reduction of graphite oxide with a series of chemical reagents and high-temperature treatment. Hydrazine hydrate, hydroxylamine hydro-chloride, sodium borohydride, and sodium sulfite were used as reducing agents. The obtained materials were studied by elemental and thermal gravimetric analyses, scanning electron microscopy, X-ray diffraction, and IR and Raman spectroscopy. Depending on the used reducing agents, the graphene-like materials contained different amounts of residual oxygen.