Development of Diamond-Carbon Nanotube Hybrid Materials

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Diamond has unique physical properties and recent progress in CVD diamond process provided semi-conductor diamond thin films. We have first discovered that several metals or metal oxide loaded on powdered diamonds surface exhibited very high catalytic activities in several reactions involving methane and lower hydrocarbons. This research is extent ion of diamond catalyzed reactions of hydrocarbons on metal loaded oxidized diamond to give diamond and carbon nanotube hybrid materials. Diamond is composed of sp3 carbons whereas carbon nanotube is composed of sp2 carbons. If diamond and carbon nanotube hybrid materials could be synthesized, unique physical properties would be expected. From these perspectives, this research was planned and synthesis of diamond-carbon nanotube hybrid material was successfully achieved.Several iron group metal loaded diamond powder was hydrogen reduced and reacted with methane and ethane at an elevated temperature of 400 to 800 ℃. Ni and Pd loaded diamond af … More forded a large amount of carbon nanofibers. On Ni-loaded case the maximum rate of carbon was obtained at 500 ℃ with methane and 600 ℃ with ethane, and from both hydrocarbons no nanofiber formation was observed at 650 ℃. Very small amount of carbon nanofibers were obtained on Co and Fe loaded diamond irrespective of the reaction temperature. On Fe-loaded diamond at 1000 ℃, very small amount of single wall carbon nanotube directly bonded to diamond surface was obtained by TEM observation.On the contrary, with Pd-loaded case carbon nanofibers were produced at higher temperature of 500 to 800 ℃, and even at 800 ℃ a large amount of carbon nanofibers were produced both from methane and ethane. In addition, at 800 ℃ with ethane as a carbon source over Pd-loaded diamond catalyst, very thick carbon fibers were produced by the combinations of initially produced thin carbon fibers.Metal catalyzed carbon nanofiber growth mechanism by the decomposition of hydrocarbon was clarified and this shed light to the design of the catalyst and growth conditions. Less