Premium
Fullerol–Titania Charge‐Transfer‐Mediated Photocatalysis Working under Visible Light
Author(s) -
Park Yiseul,
Singh N. Jiten,
Kim Kwang S.,
Tachikawa Takashi,
Majima Tetsuro,
Choi Wonyong
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200901704
Subject(s) - visible spectrum , photocatalysis , photochemistry , photocurrent , absorption (acoustics) , adsorption , electron transfer , chemistry , irradiation , absorption spectroscopy , materials science , optoelectronics , catalysis , optics , organic chemistry , physics , nuclear physics , composite material
The development of visible‐light‐active photocatalysts is being investigated through various approaches. In this study, C 60 ‐based sensitized photocatalysis that works through the charge transfer (CT) mechanism is proposed and tested as a new approach. By employing the water‐soluble fullerol (C 60 (OH) x ) instead of C 60 , we demonstrate that the adsorbed fullerol activates TiO 2 under visible‐light irradiation through the “surface–complex CT” mechanism, which is largely absent in the C 60 /TiO 2 system. Although fullerene and its derivatives have often been utilized in TiO 2 ‐based photochemical conversion systems as an electron transfer relay, their successful photocatalytic application as a visible‐light sensitizer of TiO 2 is not well established. Fullerol/TiO 2 exhibits marked visible photocatalytic activity not only for the redox conversion of 4‐chlorophenol, I − , and Cr VI , but also for H 2 production. The photoelectrode of fullerol/TiO 2 also generates an enhanced anodic photocurrent under visible light as compared with the electrodes of bare TiO 2 and C 60 /TiO 2 , which confirms that the visible‐light‐induced electron transfer from fullerol to TiO 2 is particularly enhanced. The surface complexation of fullerol/TiO 2 induced a visible absorption band around 400–500 nm, which was extinguished when the adsorption of fullerol was inhibited by fluorination of the surface of TiO 2 . The transient absorption spectroscopic measurement gave an absorption spectrum ascribed to fullerol radical cations (fullerol .+ ) the generation of which should be accompanied by the proposed CT. The theoretical calculation regarding the absorption spectra for the (TiO 2 cluster+fullerol) model also confirmed the proposed CT, which involves excitation from HOMO (fullerol) to LUMO (TiO 2 cluster) as the origin of the visible‐light absorption.