Hollow-needle-like nanocarbon with inner wall discriminating chirality

Abstract

Pore surface and structural properties are key factors in 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 sublimation behavior. A high-yielding carbon source with alkynyl groups was used, and a typical chiral molecule was mixed to induce the chiral orientation of fullerene on the pore surface, imparting a 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 in an inert atmosphere to form nanocarbons with the morphology unchanged. Nanocarbons synthesized at 700 °C possessed a core-shell structure with the fullerene nanorod as the core and the amorphous carbon as the shell. An increase in heat-treatment temperature caused fullerene sublimation to leave hollow-needle-like nanocarbon. Further, fullerene molecules were partially retained on the inner pore wall surface of the hollow structure, provoking the chiral discriminating ability of the hollow-needle-like nanocarbon when used as an electrode for oxidizing the chiral molecule transferred through pores. The ability was lost by nanocarbon heat-treated at 900 °C because of the excessive removal of the fullerene molecule. The hollow-needle-like nanocarbon would be an advanced electrode material for chiral discrimination by combining the ability with other advantages of carbon materials, such as electron conductivity and chemical stability.