Journal
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
Volume 207, Issue 1, Pages 135-143Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.jphotochem.2008.12.018
Keywords
Charge separation; Photocurrents; Electron transfer; Nanosheet; Mesoporous silica; Organic-inorganic hybrids; Porphyrin; Viologen
Categories
Funding
- Ministry of Education, Culture, Sports, Science and Technology of Japan. [19049009, 20043029]
- Grants-in-Aid for Scientific Research [20043029, 19049009] Funding Source: KAKEN
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UV-light induced redox reactions between cationic porphyrins (H2TMPyP) and methyl viologen (MV2+) separately incorporated in titania nanosheets (TNS) and cubic-mesoporous silica (MPS) integrated films, respectively, were investigated. In this system. the following two modified hybrids, i.e., the normally stacked (MV2+-TNS)/(H2TMPyP-MPS) on a FTO electrode and the inversely stacked (H2TMPyP-MPS)/(TNS) films on a FTO electrode were examined. In accordance with the expected electron flow from H2TMPyP to MV2+, cathodic photocurrents were observed for the normally stacked film in acetonitrile (CH3CN) under a negative bias voltage of -0.4V. However, under the influence of a positive bias voltage of +0.3 V, anodic photocurrents were observed even in CH3CN. On the other hand, anodic photocurrents were also observed in water for the normally stacked films at both bias voltages of +0.3 and -0.4V due to photoreduction followed by proton abstraction of the H2TMPyP molecules from H2O within the MPS nano-cavities. In addition, ca. 0.98 mC of the photocurrents were determined in water for the inversely stacked (H2TMPyP-MPS)/(TNS) films without MV2+, of which ca. 50% resulted in the oxidative consumption of H2TMPyP in the MPS cavities. (C) 2009 Elsevier BY. All rights reserved.
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