Composites of molecular-anchored graphene and nanotubes with multitubular structure: a new type of carbon electrode.

Graphene-carbon nanotube nanocomposites that contain multitubular co-axial and hollow cavity microstructures are prepared. Nanometer-scale graphene sheets are anchored with oxalic acid and consequently linked to each other via oxalyl bonding, thereby self-assembling into numerous outer tubes with distinct borders and a homogeneous thickness along the innermost pristine tube, which acts as a template. The resulting interstitial inclusion of oxalic acid into the graphene stacking modifies both the surface and the bulk properties of the newly formed tubes. It is observed that the unique microstructure of the modified graphene-carbon nanotube nanocomposite significantly facilitates the insertion and extraction of lithium, demonstrating superior electrochemical performance as anodes for lithium-based batteries. This facile chemical approach provides a new graphene architecture, showing superior stability, for use as anode material in lithium ion batteries.

Synthesis of ternary metal nitride nanoparticles using mesoporous carbon nitride as reactive template.

Mesoporous graphitic carbon nitride was used as both a nanoreactor and a reactant for the synthesis of ternary metal nitride nanoparticles. By infiltration of a mixture of two metal precursors into mesoporous carbon nitride, the pores act first as a nanoconfinement, generating amorphous mixed oxide nanoparticles. During heating and decomposition, the carbon nitride second acts as reactant or, more precisely, as a nitrogen source, which converts the preformed mixed oxide nanoparticles into the corresponding nitride (reactive templating). Using this approach, ternary metal nitride particles with diameters smaller 10 nm composed of aluminum gallium nitride (Al-Ga-N) and titanium vanadium nitride (Ti-V-N) were synthesized. Due to the confinement effect of the carbon nitride matrix, the composition of the resulting metal nitride can be easily adjusted by changing the concentration of the preceding precursor solution. Thus, ternary metal nitride nanoparticles with continuously adjustable metal composition can be produced.

Ionothermal synthesis of crystalline, condensed, graphitic carbon nitride.

Herein we report the synthesis of a crystalline graphitic carbon nitride, or g-C(3)N(4), obtained from the temperature-induced condensation of dicyandiamide (NH(2)C(=NH)NHCN) by using a salt melt of lithium chloride and potassium chloride as the solvent. The proposed crystal structure of this g-C(3)N(4) species is based on sheets of hexagonally arranged s-heptazine (C(6)N(7)) units that are held together by covalent bonds between C and N atoms which are stacked in a graphitic, staggered fashion, as corroborated by powder X-ray diffractometry and high-resolution transmission electron microscopy.

High-surface-area TiO2 and TiN as catalysts for the C-C coupling of alcohols and ketones.

To design more sustainable processes for the alkylation of ketones, the use of both atom-ineffective leaving groups such as halides and boron as well as noble-metal-based catalysts should be avoided. For that purpose, high-surface-area titanium nitride was prepared from high-surface-area titanium dioxide using cyanamide as a transcription agent. The resulting nitride as well as the initial oxide proved to be effective and versatile catalysts for the alkylation of ketones with alcohols. Interestingly, the TiN catalyst yields unsaturated compounds, while the oxide-based catalyst mainly yields saturated coupling products. As a result of its metallic properties, TiN shows a strong tendency to catalyse the dehydrogenation of alcohols, which then undergo aldol condensation with ketones. In contrast, TiO(2) promotes the direct nucleophilic attack of ketones on alcohols.

Cytotoxicity and inflammatory potential of soot particles of low-emission diesel engines.

We evaluated, in vitro, the inflammatory and cytotoxic potential of soot particles from current low-emission (Euro IV) diesel engines toward human peripheral blood monocyte-derived macrophage cells. The result is surprising. At the same mass concentration, soot particles produced under low-emission conditions exhibit a much highertoxic and inflammatory potential than particles from an old diesel engine operating under black smoke conditions. This effect is assigned to the defective surface structure of Euro IV diesel soot, rendering it highly active. Our findings indicate that the reduction of soot emission in terms of mass does not automatically lead to a reduction of the toxic effects toward humans when the structure and functionality of the soot is changed, and thereby the biological accessibility and inflammatory potential of soot is increased.

Individual Fe-Co alloy nanoparticles on carbon nanotubes: structural and catalytic properties.

We report the synthesis, characterization, and catalytic performance of Fe-Co alloy nanoparticles inside the tubular channel of carbon nanotubes. The homogeneous distributions of Fe and Co in the isolated nanoparticles were evidenced confidentially by bulk and surface structural and compositional characterizations, that is, scanning electron microscopy, high-resolution transmission electron microscope in combination with elemental mapping by energy dispersive X-ray spectroscopy and electron energy-loss spectroscopy, powder X-ray diffraction, and X-ray photoelectron spectroscopy. We also demonstrate for the first time an unusual synergism in alloy catalysis. The alloy nanoparticles with widely varying Co/Fe ratio are kept as active as Co for the H 2 production from NH 3 decomposition. The stability of Co was significantly improved by alloying with Fe. We expect our experimental method to be a general approach to elucidate the synergism phenomenon in alloy catalysis.