Journal
APPLIED CATALYSIS B-ENVIRONMENTAL
Volume 176, Issue -, Pages 678-686Publisher
ELSEVIER
DOI: 10.1016/j.apcatb.2015.04.053
Keywords
TiO2 mesocrystals; Photoredox activity; Crystal face dependence
Funding
- Innovative Project for Advanced Instruments, Renovation Center of Instruments for Science Education and Technology, Osaka University
- Ministry of Education, Culture, Sports, Science and Technology (MEXT) of the Japanese Government. [25220806, 25810114]
- Grants-in-Aid for Scientific Research [25810114] Funding Source: KAKEN
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The photocatalytic performance of nanocrystalline TiO2 is crucially influenced by specific facet-induced adsorption and charge separation. Herein, different morphologies of anatase TiO2 mesocrystal superstructures with directed nanocrystal assembly were controllably synthesized by introducing NH4F as an orientation-directing agent. The ratio of the basal and lateral external surfaces of mesocrystals was tuned from 1.1 to 5.8 by increasing the amount of NH4F, along with that of {0 0 1} and {1 0 1} facets of incubated TiO2 nanocrystals from 0.56 to 0.76. With increasing the ratios, the mesocrystal superstructures exhibited higher photo-oxidation activities in the degradation of 4-chlorophenol (by 1.7 times) and lower activities in Cr6+ reduction (by 0.47 times) and H-2 generation (by 0.32 times). The H-2 production from dye-sensitized TiO2 mesocrystal using eosin Y (pH 10) and Ruthenizer 470 (pH 3) are further identify the dominant facets in photocatalysis. It was confirmed that the mesocrystal superstructures with higher ratio of {0 0 1}/{1 0 1} are more effectively (by 6 times) adsorbed the dye sensitizers under acidic conditions and enhanced charge separation by efficient electron migration through the incubated nanocrystal network and crystal-facet-specific modification of the Pt cocatalyst. The synergetic crystal-facet engineering between mesocrystals and incubated nanocrystals will significantly improve the efficiencies and selectivities of semiconductor photocatalysts. (C) 2015 Elsevier B.V. All rights reserved.
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