Hollow-needle-like nanocarbon with chirality-discriminating inner walls

Pore surface and structural properties are key factors when producing functional porous carbon materials; however, the efficient control of both factors has not been fully investigated. In this study, fullerene was used as a pore template and a surface structure modifier to achieve simultaneous control, given its ability to form various nanocrystals and its sublimation behavior. A high-yielding carbon source with alkynyl groups was used, and a typical chiral molecule was added to induce the chiral orientation of fullerene on the pore surface, imparting chiral-discriminating ability. Needle-like deposits were generated via the slow evaporation of the solvent to dissolve fullerene, the carbon source, and the chiral molecule, followed by heat treatment under an inert atmosphere to form nanocarbon with the morphology preserved. Nanocarbon synthesized at 700 °C possessed a core-shell structure with a fullerene nanorod as the core and amorphous carbon as the shell. An increase in the heat-treatment temperature caused fullerene sublimation, leaving hollow-needle-like nanocarbon. Further, fullerene molecules were partially retained on the inner pore wall surface of the hollow structure, promoting the chiral-discriminating ability of the hollow-needle-like nanocarbon when used as an electrode for oxidizing chiral molecules transferred through the pores. Nanocarbon heat-treated at 900 °C lost this ability because of the excessive removal of fullerene molecules. The hollow-needle-like nanocarbon could be an advanced electrode material for chiral discrimination by combining its abilities with other advantages of carbon materials, such as electron conductivity and chemical stability.