Development of Diamond-Carbon Nanotube Hybrid Materials

金刚石具有独特的物理性质，近年来CVD金刚石工艺的进展提供了半导体金刚石薄膜。我们首次发现，载于粉末金刚石表面的几种金属或金属氧化物在几种涉及甲烷和低碳氢化合物的反应中表现出很高的催化活性。本研究是利用金刚石催化碳氢化合物在金属负载氧化金刚石上的反应，得到金刚石与碳纳米管的杂化材料。金刚石是由sp3碳原子组成，而碳纳米管是由sp2碳原子组成。如果金刚石与碳纳米管的杂化材料能够被合成，其独特的物理性能将被期待。从这些角度出发，对本研究进行了规划并成功合成了金刚石-碳纳米管杂化材料。在400 ~ 800℃的高温下，对几种铁族金属负载的金刚石粉进行氢还原，与甲烷和乙烷反应。负载Ni和Pd的金刚石材料中含有大量的碳纳米纤维。负载ni的情况下，在500℃与甲烷和600℃与乙烷反应时碳的生成速率最大，650℃与乙烷反应均未形成纳米纤维。无论反应温度如何，负载钴和铁的金刚石表面都能得到极少量的碳纳米纤维。在1000℃负载铁的金刚石表面，透射电镜观察到极少量的单壁碳纳米管直接与金刚石表面结合。相反，负载pd的情况下，在500 ~ 800℃的高温下可以制备出纳米碳纤维，即使在800℃的高温下，甲烷和乙烷都可以制备出大量的纳米碳纤维。此外，在800℃下，以乙烷为碳源，在负载pd的金刚石催化剂上，由最初生产的薄碳纤维组合而成的非常厚的碳纤维。阐明了金属催化碳纳米纤维分解碳氢化合物的生长机理，为催化剂和生长条件的设计提供了依据。少

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