title: Clusterization, electrophoretic deposition, and photoelectrochemical properties of fullerene-functionalized carbon nanotube composites.
abstract: We have successfully developed a new methodology for the self-organization of C(60) molecules on the sidewall of carbon nanotubes for use in photoelectrochemical devices. Novel nanocarbon composites of fullerene (e.g., C(60)) and highly soluble, chemically functionalized single-walled carbon nanotubes (f-SWNT) have been prepared by the rapid injection of a poor solvent (e.g., acetonitrile) into a mixed solution of C(60) and f-SWNT in o-dichlorobenzene. Measurements by using scanning electron microscopy of cast samples revealed that the composites are categorized into three groups; i) f-SWNT bundles covered with layers of C(60) molecules, ii) round, large C(60) clusters (sizes of 500-1000 nm) containing f-SWNT, and iii) typical, round C(60) clusters (sizes of 150-250 nm). The electrophoretic deposition of the composites onto a nanostructured SnO(2) electrode yielded the hierarchical film with a gradient composition depending on the difference in the mobilities of C(60) and f-SWNT during the electrophoretic process. The composite film exhibited an incident photon-to-photocurrent efficiency as high as 18 % at lambda=400 nm under an applied potential of 0.05 V vs. SCE. The photocurrent generation efficiency is the highest value among carbon nanotube-based photoelectrochemical devices in which carbon nanotubes are deposited electrophoretically, electrostatically or covalently onto semiconducting electrodes. The highly aligned structure of C(60) molecules on f-SWNT can rationalize the efficient photocurrent generation. The results obtained here will provide valuable information on the design of carbon nanotube-based molecular devices.
authors.affiliation: Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan.
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Umeyama
authors.forename: Noriyasu
authors.initials: N
authors.lastname: Tezuka
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Fujita
authors.forename: Shinya
authors.initials: S
authors.lastname: Hayashi
authors.forename: Naoki
authors.initials: N
authors.lastname: Kadota
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Matano
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Imahori