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The method to synthesize single-walled carbon nanohorns ͑SWCNHs͒ using gas-injected arc in water ͑GI-AIW͒ has been experimentally studied. GI-AIW is known as one of the cost-effective methods to obtain SWCNHs. It was revealed that the yield of SWCNHs significantly decreases with the increase in water temperature although the purity of SWCNHs is not dependent on the temperature change. Then the model of relevant reactions in the GI-AIW system was proposed by accounting the emission of carbon vapor, formation of SWCNHs, and diffusion of water vapor in three zones inside the cathode hole ͑arc plasma zone, quenching zone, and downstream zone͒. The side reaction between H 2 O and C produces H 2 gas and consumes a certain amount of carbon vapor, resulting in the hindered SWCNH formation. Moreover the observation of the optical spectra emitting from the arc plasma zone strongly supported that the H 2 generating reaction does not occur at arc plasma zone since N 2 flow can purge H 2 O out. The model proposed in this study can precisely explain the correlation between H 2 gas production and water temperature.

The present study examined the formation of single-walled carbon nanohorns (SWCNHs) dispersed with nanoparticles of a Pd alloy that is composed of one of nine elementsAu, Pt, Cu, Fe, Ni, Ti, Mo, W, and Nbby a modified gas-injected arc-in-water (GI-AIW) method incorporating a hollow graphite anode into which wires of Pd and an alloying component were inserted to generate arc discharge. The following requirement to realize the formation of Pd-alloy nanoparticles dispersed in SWCNHs was recognized: the boiling points of the alloying component must be below the 5000 K arc plasma temperature. When this requirement is satisfied, the boiling point of this component could be used as a threshold to judge whether Pd should be enriched or diluted in the products formed by the arc discharge process. Particle size analysis revealed that nanoparticles of Pd alloy containing Au show significantly high dispersion. In contrast, alloys with Cu produce relatively large alloy nanoparticles. The tendency of the average size of the alloy nanoparticles produced by this method can be correlated by a simple equation, taking into account the ratio of boiling point to melting point, surface tension, and gas diffusivity of the alloying components.

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The effect of dispersion of Fe/Fe2O3 nanoparticles in sulfonated single-walled carbon nanohorns (SO3H/SWCNHs) on their catalytic activity for the esterification of palmitic acid was investigated.

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Multi-walled carbon nanotubes (CNTs) were synthesized directly on stainless steel film thermally deposited on an alumina plate. To activate the growth of CNTs, the stainless steel film was reduced in H 2 stream without oxidation step. The electrical resistivity of the CNT film synthesized by this way turned to be 1/190 of CNT film synthesized by a conventional way using catalyst preparation method with magnetron sputtering. Dielectrophoretic (DEP) particle capture was demonstrated using the patterned CNT film synthesized on stainless steel film, and it was observed that carbon nanohorns (CNHs) dispersed with Pd nanoparticles (Pd-CNHs) and Pd-Au alloy nanoparticles (Pd/Au-CNHs) were captured at the CNT electrodes due to the high electric field strength there. In this DEP capture, Pd-CNHs were enriched in the present condition. The temperature to deposit stainless steel film and the influence of oxidation step were also investigated for the growth of CNTs. V