C60-Incorporated Carbon Nanohorns: Control of Filling and Releasing

Single-wall carbon nanohorn (SWNH) has structures similar to single wall carbon nanotube, and nanometer-scaled holes were opened through the walls by heating in oxygen (SWNHox). Recently, we have succeeded in a large-scale preparation of C$_{60}$-incorporated SWNHox (C$_{60}$@SWNHox) at room temperature in liquid phase by our new method of ``nano-precipitation.'' In this report, we show that incorporation of C$_{60}$ inside SWNHox could be confirmed by TEM observation, Raman spectrum measurements, and X-ray diffraction measurements. Quantity of C$_{60}$ incorporated inside SWNHox was estimated from thermogravimetric analysis. The release rates of C$_{60}$ from C$_{60}$@SWNHox in solutions were able to be clarified by UV/Vis absorption measurements. Through these investigations, we found that the filling quantities and release rates of C$_{60}$ were able to be controlled easily for SWNHs. These are advantages of large-diameters of the tubes to which C$_{60}$ molecules are bound moderately.