Carbon-nanotube-based hybrid materials: nanopeapods.

This review article focuses on the structures and properties of novel hybrid nanocarbon materials, which are created by incorporating atoms and molecules into the hollow spaces of carbon nanotubes (CNTs); thus they are called nanopeapods. After dealing with synthesis procedures, we discuss the structures and electronic properties of the hybrid materials based on high-resolution transmission electron microscopy (HRTEM), electron energy-loss spectroscopy (EELS), X-ray and electron diffraction, scanning tunneling microscopy (STM), and field-effect transistor transport measurements. Utilization of the low-dimensional nanosized spaces of CNTs to produce novel low-dimensional nanocluster, nanowire, and nanotube materials is also discussed.