Single-molecule, single-particle fluorescence imaging of TiO2-based photocatalytic reactions

Tachikawa, Takashi; Majima, Tetsuro

doi:10.1039/b919698f

Cited by 171 publications

(148 citation statements)

References 191 publications

(272 reference statements)

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“…As shown in Figure 17, higher percentages of {101} facets clearly correlate with higher photocatalytic activity for both partially fluorinated and NaOH-treated samples. Similar results were obtained by Tachikawa et al [116,117] who directly evaluated the photocatalytic activity of an individual anatase TiO 2 single crystal using as-synthesized redox-responsive boron dipyrromethane (DN-BODIPY) as the fluorescent probe and found that most fluorescence spots were preferentially located on {101} surface of crystals, as shown in Figure 18, even if the surface area of the {001} facets was more than two times higher than that of {101} facets. This finding may be helpful to interpret some important photocatalytic processes.…”

Section: Recent Controversial Resultssupporting

confidence: 71%

Specific Facets-Dominated Anatase TiO2: Fluorine-Mediated Synthesis and Photoactivity

2013

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Semiconductors crystal facet engineering has become an important strategy for properly tuning and optimizing both the physicochemical properties and the reactivity of photocatalysts. In this review, a concise survey of recent results obtained in the field of specific surface-oriented anatase TiO 2 crystals preparation is presented. The attention is mainly focused on the fluorine-mediated hydrothermal and/or solvothermal processes employed for the synthesis and the assembly of anatase micro/nanostructures with dominant {001} facets. Their peculiar photocatalytic properties and potential applications are also presented, with a particular focus on photocatalysis-based environmental clean up and solar energy conversion applications. Finally, the most promising results obtained in the engineering of TiO 2 anatase crystal facets obtained by employing alternative, possibly more environmentally friendly methods are critically compared.

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Section: Recent Controversial Resultssupporting

confidence: 71%

Specific Facets-Dominated Anatase TiO2: Fluorine-Mediated Synthesis and Photoactivity

2013

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“…88,89 Bian et al 85 applied this technique to determine the location of reactive sites on plate-like TiO 2 MCs by using a redox-responsive fluorogenic probe. By accepting electrons from photoexcited TiO 2 , nonfluorescent 8-(3,4-dinitrophenyl)-1,3,5,7-tetramethyl-4,4-difluoro-4-bora-3a,4a-diaza-sindacene (DN-BODIPY; fluorescence quantum yield F fl o10 À4 in methanol) was reduced to form highly fluorescent 4-hydroxyamino-3-nitrophenyl-BODIPY (HN-BODIPY; F fl ¼ 0.50 in methanol) (Figure 8a).…”

Section: Electron Transport In MCmentioning

confidence: 99%

Metal oxide mesocrystals with tailored structures and properties for energy conversion and storage applications

Tachikawa

Majima

2014

NPG Asia Mater

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Mesocrystals (MCs) are superstructures with a crystallographically ordered alignment of nanoparticles. Owing to their organized structures, MCs posses some unique characteristics such as a high surface area, pore accessibility, and good electronic conductivity and thermal stability; thus, MCs could be beneficial for many areas of research and application. This review begins with a description of the common synthesis strategies for, and characterization and fundamental properties of metal oxide MCs. Newly developed analytical methods (that is, photoconductive atomic force microscopy and single-molecule, single-particle fluorescence microscopy) for unraveling the charge transport and photocatalytic properties of individual MCs are then introduced. Further, recent developments in the applications of various metal oxide MCs, especially in the fields of energy conversion and storage, are also reviewed. Finally, several perspectives in terms of future research on MCs are highlighted. NPG Asia Materials (2014) 6, e100; doi:10.1038/am.2014.21; published online 16 May 2014 Keywords: energy storage; mesocrystal; metal oxide; photocatalysis; solar energy conversion; superstructure INTRODUCTIONThe self-assembly of nanoparticle building blocks into highly ordered superstructures is one of the actively pursued research topics in materials science and technology. 1-4 Such hierarchical architectures have potentially tunable electronic, optical and magnetic properties, which promise various applications ranging from catalysis to optoelectronics. A mesocrystal (MC), which was first introduced by Cölfen in the early years of 2000s, is defined as a superstructure consisting of nanoparticles on the scale of several hundred nanometers to micrometers. [5][6][7][8][9][10][11] In contrast to the classical mechanism of atom/ ion-mediated growth of a single crystal, the particle-mediated growth mechanisms of MCs are termed as non-classical crystallization (Figure 1). This definition has been developed in recent years, where MCs are defined entirely according to their structures rather than their formation mechanism. 12 In this decade, a variety of MCs of metal oxides (for example, TiO 2 , 13-23 ZnO, [24][25][26][27][28][29][30][31][32][33][34] Among metal oxides, TiO 2 is used in many applications that deal with environmental and energy problems (for example, photodegradation of pollutants, 67 water splitting for H 2 evolution, 68 dyesensitized solar cells 68 and lithium-ion batteries 69 ) owing to its

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“…[1][2][3] Various strategies have been attempted to increase the visible light absorption of wide bandgap semiconductors such as doping with metal or nonmetal elements, 4-8 surface deposition of noble metals for plasmon effects, [9][10][11] and coupling with smaller bandgap semiconductors, 12-14 quantum dots 15,16 and dyes. [17][18][19] Among them, dye sensitization has been successfully demonstrated for many applications such as photocatalytic hydrogen production 20,21 and dye-sensitized solar cells.…”

Section: Introductionmentioning

confidence: 99%

Visible light sensitization of TiO₂ nanoparticles by a dietary pigment, curcumin, for environmental photochemical transformations

2017

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The use of curcumin, an active ingredient of turmeric powder (a dye component in curry), as a TiO 2 photosensitizer was investigated in terms of the photochemical and photoelectrochemical (PEC) properties.Owing to its strong visible light absorption and strong surface complexation, the curcumin-sensitized TiO 2 composite exhibited notable activities for the photochemical degradation of organic compounds, the reduction of chromate (Cr(VI)), and the generation of OH radicals and H 2 O 2 through the reduction of O 2 under visible light (l > 420 nm). Various spectroscopic methods confirmed the anchoring of curcumin on TiO 2 and the photochemical and PEC properties of curcumin/TiO 2 were compared with those of TiO 2 sensitized by a ruthenium complex (RuL 3 ) that has been frequently employed as a visible light sensitizer. Curcumin/TiO 2 exhibited consistently higher photochemical and PEC activities than RuL 3 /TiO 2 over a wide pH range in an aquatic environment. These results confirm the practical viability of using a natural food dye, curcumin, as an efficient, eco-friendly, and cheap photo-sensitizer of TiO 2 for solar environmental applications. However, it should be noted that curcumin on TiO 2 like other dye sensitizers is degraded as a result of the sensitizing reactions in water and should be considered as a sensitizing reagent, not a photocatalyst.

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Single-molecule, single-particle fluorescence imaging of TiO2-based photocatalytic reactions

Cited by 171 publications

References 191 publications

Specific Facets-Dominated Anatase TiO2: Fluorine-Mediated Synthesis and Photoactivity

Specific Facets-Dominated Anatase TiO2: Fluorine-Mediated Synthesis and Photoactivity

Metal oxide mesocrystals with tailored structures and properties for energy conversion and storage applications

Visible light sensitization of TiO₂ nanoparticles by a dietary pigment, curcumin, for environmental photochemical transformations

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Single-molecule, single-particle fluorescence imaging of TiO2-based photocatalytic reactions

Cited by 171 publications

References 191 publications

Specific Facets-Dominated Anatase TiO2: Fluorine-Mediated Synthesis and Photoactivity

Specific Facets-Dominated Anatase TiO2: Fluorine-Mediated Synthesis and Photoactivity

Metal oxide mesocrystals with tailored structures and properties for energy conversion and storage applications

Visible light sensitization of TiO2 nanoparticles by a dietary pigment, curcumin, for environmental photochemical transformations

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Visible light sensitization of TiO₂ nanoparticles by a dietary pigment, curcumin, for environmental photochemical transformations