title: Visible Light Sensitized Production of Hydroxyl Radicals Using Fullerol as an Electron-Transfer Mediator.
abstract: Fullerenes and their derivatives are known to photosensitize the production of singlet oxygen (1O2), but their role in generating hydroxyl radical (•OH) under visible light has not been reported. Here, we demonstrate that fullerol can mediate the electron transfer from Rhodamine B dye to O2under visible light irradiation, achieving simultaneous dye decolorization and•OH-induced degradation of 4-chlorophenol. The hydroxyl radical is proposed to be produced via a consecutive reduction of molecular oxygen by fullerol anion radical, which is formed through the electron transfer from the dye to the triplet state of fullerol. Mechanistic investigations using various probe reagents such as superoxide dismutase (superoxide quencher), t-butanol (•OH quencher), and coumarin (•OH probe) provided indirect evidence for the generation of•OH under visible light. Furthermore, spin trapping technique directly detected the oxidizing species such as•OH, HO2•, and1O2in the visible light irradiated solution of RhB/fullerol mixture. It was proposed that the photochemical oxidation mechanism depends on pH:•OH production is favored at acidic pH through fullerol-mediated sequential electron transfer while1O2is generated as a main oxidant at neutral and alkaline condition through the energy-transfer process. Therefore, the photochemical oxidation can be switchable between•OH-driven and1O2-driven mechanism by a simple pH adjustment.
authors: Division of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH) , Pohang 37673, Korea.
authors: Jonghun
authors: J
authors: Lim
authors: Division of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH) , Pohang 37673, Korea.
authors: Hyejin
authors: H
authors: Kim
authors: Department of Civil & Environmental Engineering, Rice University , Houston, Texas 77005, United States.
authors: Pedro J J
authors: PJ
authors: Alvarez
authors: School of Civil, Environmental, and Architectural Engineering, Korea University , Seoul 136-701, Korea.
authors: Jaesang
authors: J
authors: Lee
authors: Division of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH) , Pohang 37673, Korea.
authors: Wonyong
authors: W
authors: Choi
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D004583:Electrons; D017665:Hydroxyl Radical / Q000737:chemistry*; D008027:Light; D013481:Superoxides / Q000378:metabolism
chemical_list: D013481:Superoxides; D017665:Hydroxyl Radical