Japan Science and Technology Agency (Kawaguchi-shi, JP) earned Patent 7,771,697 for a method for preparing functional nanomaterials utilizing endothermic reaction
Inventors Tadashi Mitsui, Takashi Sekiguchi, Mika Gamo, Yafei Zhang and Toshihiro Ando
disclosed a method whereby a functional nanomaterial such as a monolayer carbon nanotube, a monolayer boron nitride nanotube, a monolayer silicon carbide nanotube, a multilayer carbon nanotube with the number of layers controlled, a multilayer boron nitride nanotube with the number of layers controlled, a multilayer silicon carbide nanotube with the number of layers controlled, a metal containing fullerene, and a metal containing fullerene with the number of layers controlled is produced at a high yield.
According to the Japan Science and Technology Agency method, when a multilayer carbon nanotube is formed by a chemical vapor deposition or a liquid phase growth process, an endothermic reaction aid (H2S) is introduced in addition to a primary reactant (CH4, H2) in the process to form a monolayer carbon nanotube.
Japan Science and Technology Agency’s method of making at a high yield a functional nanomaterial such as a monolayer carbon nanotube, a monolayer boron nitride nanotube, a monolayer silicon carbide nanotube, a multilayer carbon nanotube with the number of layers controlled, a multilayer boron nitride nanotube with the number of layers controlled and a multilayer silicon carbide nanotube with the number of layers controlled, a metal containing fullerene, and a metal containing fullerene with the number of layers controlled, the method utilizing endothermic reactions.
The method of making a functional nanomaterial utilizing endothermic reactions is characterized in that when a multilayer carbon nanotube is formed by a chemical vapor deposition process or a liquid phase growth process an endothermic reaction aid is introduced in addition to a primary reactant in the process to form a monolayer carbon nanotube.
The chemical vapor deposition process may here be a process that uses, e.g., a combination of a volatile hydrocarbon and hydrogen as the primary reactant which is excited in the presence of fine iron particles as a catalyst in microwave plasma to form a multilayer carbon nanotube.
The liquid phase growth process may be a process that uses, e.g., an organic liquid as the primary reactant and heats the organic liquid in the presence of fine iron particles as a catalyst to form a multilayer carbon nanotube.
The endothermic reaction aid may comprise, e.g., any one or any combination of hydrogen sulfide (H2S), carbon monoxide (CO), nitrous oxide (N2O), sulfur and water (H2O).
According to the method with the features mentioned above, monolayer carbon nanotubes can be formed at an improved yield by virtue of the fact that while a carbon nanotube is being grown, the endothermic reaction aid deters the growth of multilayer walls of the carbon nanotube by an impeding reaction accompanied by heat absorption.
The invention also provides a method of making a functional nanomaterial utilizing endothermic reactions, characterized in that it comprises converting a multilayer nanotube into a monolayer nanotube by heat-treating the multilayer nanotube in a gas or liquid, or a fluid, containing an endothermic reactant.
The multilayer nanotube may be, e.g., a multilayer carbon nanotube, a multilayer boron nitride nanotube or a multilayer silicon carbide nanotube.
According to these features, the endothermic reactant detaches multilayer walls of the multilayer nanotube through a peeling reaction accompanied by heat absorption. The endothermic reaction allows the rate of the peeling reaction to be well controllable and multilayer nanotubes to be converted into monolayer nanotubes at an extremely high yield.
FIG. 2 shows pictures (a), (b) and (c) taken by a transmission electron microscope of carbon nanotube specimens formed with varied proportions of a primary reactant and a reaction aid.
The method of making a functional nanomaterial utilizing endothermic reactions is characterized in that when a multilayer carbon nanotube is formed by a chemical vapor deposition process or a liquid phase growth process an endothermic reaction aid is introduced in addition to a primary reactant in the process to form a monolayer carbon nanotube.
The chemical vapor deposition process may here be a process that uses, e.g., a combination of a volatile hydrocarbon and hydrogen as the primary reactant which is excited in the presence of fine iron particles as a catalyst in microwave plasma to form a multilayer carbon nanotube.
The liquid phase growth process may be a process that uses, e.g., an organic liquid as the primary reactant and heats the organic liquid in the presence of fine iron particles as a catalyst to form a multilayer carbon nanotube.
The endothermic reaction aid may comprise, e.g., any one or any combination of hydrogen sulfide (H2S), carbon monoxide (CO), nitrous oxide (N2O), sulfur and water (H2O).
According to the method with the features mentioned above, monolayer carbon nanotubes can be formed at an improved yield by virtue of the fact that while a carbon nanotube is being grown, the endothermic reaction aid deters the growth of multilayer walls of the carbon nanotube by an impeding reaction accompanied by heat absorption.
The invention also provides a method of making a functional nanomaterial utilizing endothermic reactions, characterized in that it comprises converting a multilayer nanotube into a monolayer nanotube by heat-treating the multilayer nanotube in a gas or liquid, or a fluid, containing an endothermic reactant.
The multilayer nanotube may be, e.g., a multilayer carbon nanotube, a multilayer boron nitride nanotube or a multilayer silicon carbide nanotube.
According to these features, the endothermic reactant detaches multilayer walls of the multilayer nanotube through a peeling reaction accompanied by heat absorption. The endothermic reaction allows the rate of the peeling reaction to be well controllable and multilayer nanotubes to be converted into monolayer nanotubes at an extremely high yield.
FIG. 2 shows pictures (a), (b) and (c) taken by a transmission electron microscope of carbon nanotube specimens formed with varied proportions of a primary reactant and a reaction aid.
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