Probing Photocatalytic Active Sites on a Single Titanosilicate Zeolite with a Redox‐Responsive Fluorescent Dye

Tachikawa, Takashi; Yamashita, Soichiro; Majima, Tetsuro

doi:10.1002/ange.200904876

Cited by 18 publications

(8 citation statements)

References 22 publications

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“…The higher density or the larger number of defects could account for the transient high productivity or activity of that area ( Fig. 2A) because the crystallographic defects could serve as active sites (1,4,28). Unfortunately, the short catalytic lifetime of the middle section indicates these active sites, whatever their origin, are relatively unstable.…”

Section: Significancementioning

confidence: 99%

Superresolution fluorescence mapping of single-nanoparticle catalysts reveals spatiotemporal variations in surface reactivity

Zhang

Lucas

Song

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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For the practical application of nanocatalysts, it is desirable to understand the spatiotemporal fluctuations of nanocatalytic activity at the single-nanoparticle level. Here we use time-lapsed superresolution mapping of single-molecule catalysis events on individual nanoparticles to observe time-varying changes in the spatial distribution of catalysis events on Sb-doped TiO 2 nanorods and Au triangle nanoplates. Compared with the active sites on well-defined surface facets, the defects of the nanoparticle catalysts possess higher intrinsic reactivity but lower stability. Corners and ends are more reactive but also less stable than flat surfaces. Averaged over time, the most stable sites dominate the total apparent activity of single nanocatalysts. However, the active sites with higher intrinsic activity but lower stability show activity at earlier time points before deactivating. Unexpectedly, some active sites are found to recover their activity ("selfhealing") after deactivation, which is probably due to desorption of the adsorbate. Our superresolution measurement of different types of active catalytic sites, over both space and time, leads to a more comprehensive understanding of reactivity patterns and may enable the design of new and more productive heterogeneous catalysts.single-molecule nanocatalysis | optical superresolution imaging | photocatalysis | surface restructuring A ll kinds of nanoparticles, such as metals, metal oxides, and even nonmetals, are used as catalysts in a variety of chemical processes (1). In support of developing better and less-expensive nanoparticle catalysts, single-molecule mapping of nanocatalyst activity using superresolution imaging at the single-nanoparticle level can determine active site locations on nanoparticles and which structures are most reactive (2-5). For example, defects, corners, and edges on nanoparticle surfaces have been shown by singlemolecule, superresolution imaging of single nanocatalysts to be more active than other sites. The relative abundance of these sites on nanoparticle catalysts is important for explaining their observed reactivity (2, 4, 6-13).However, prior reports are based on longtime integrations of catalytic activity and thus do not provide information about any dynamic changes in catalytic activity, such as the time-dependent evolution of different active sites. Studies of time-varying catalytic activity are thus arguably more informative than time-averaged observations.The temporal fluctuation of catalytic activity on nanocatalysts or electrodes has been previously observed in situ at both the ensemble and single-nanoparticle level (14-17). More recently, superresolution imaging techniques have been applied to identify the spatial distribution of catalytic activity on a few different nanocatalysts including Au@SiO 2 nanorods, Au@SiO 2 nanotriangles (2, 4) and Au-CdS nanohybrids (6). The observed spatial variations in catalytic activity between different catalysts were merely attributed to possible reaction-driven surface reconstruction of...

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Section: Significancementioning

confidence: 99%

Superresolution fluorescence mapping of single-nanoparticle catalysts reveals spatiotemporal variations in surface reactivity

Zhang

Lucas

Song

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…ETS-10 is a microporous titanosilicate composed of octahedral [TiO 6 ] and tetrahedral [SiO 4 ] units that was originally discovered in 1989 by Engelhard. [1] It possesses a three-dimensional pore structure with large 12-membered ring-pore openings.…”

Section: Introductionmentioning

confidence: 99%

“…[3][4][5] Upon irradiation with pho-tons larger than the bandgap, the electrons and holes are generated and migrate through the monoatomic quantum wires to the terminal groups and defects. [6] As such, ETS-10 has inspired much interest as a photocatalyst. [7][8][9] In addition to its potential photocatalysis applications, ETS-10 has attracted considerable attention because of its applicability as a base in catalytic reactions [10][11][12][13] and also its pronounced cation-exchange capacity.…”

Section: Introductionmentioning

confidence: 99%

“Extracting” the Key Fragment in ETS‐10 Crystallization and Its Application in AM‐6 Assembly

Guo

Feng

et al. 2012

Chemistry A European J

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The mechanism of crystallization of microporous titanosilicate ETS-10 was investigated by Raman spectroscopy combined with (29)Si magic-angle spinning (MAS) NMR spectroscopy, DFT calculations, and SEM imaging. The formation of three-membered ring species is shown to be the key step in the hydrothermal synthesis of ETS-10. They are formed by means of a complex process that involves the interaction of silicate species in the reaction mixture, which promotes the dissolution of TiO(2) particles. These insights into the mechanism of ETS-10 growth led to the successful development of a new synthesis route to the vanadosilicate AM-6 that involves the use of intermediates that contain three-membered ring species as an initiator.

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“…[9][10][11] Seit kurzem wird die SMFS zur Untersuchung chemischer Reaktionen in der heterogenen Katalyse verwendet. [14] Ein ähnlicher Ansatz mit fluorogenen Substraten wurde zum Studium katalytischer Redoxreaktionen auf der Oberfläche von Goldnanopartikeln [15] und Titansilicat-Zeolithen [16] genutzt. [14] Ein ähnlicher Ansatz mit fluorogenen Substraten wurde zum Studium katalytischer Redoxreaktionen auf der Oberfläche von Goldnanopartikeln [15] und Titansilicat-Zeolithen [16] genutzt.…”

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“…Beispielsweise wurde die Spaltung fluorogener Ester genutzt, um die räumliche Verteilung der katalytisch aktiven Zentren der Esterhydrolyse auf kristallinen Partikeln zu visualisieren, [12,13] oder um das katalytische Verhalten einzelner Enzyme zu charakterisieren. [14] Ein ähnlicher Ansatz mit fluorogenen Substraten wurde zum Studium katalytischer Redoxreaktionen auf der Oberfläche von Goldnanopartikeln [15] und Titansilicat-Zeolithen [16] genutzt. ¾hnliche Studien über die Dynamik des Ligandenaustauschs an Pt-Komplexen haben den direkten Einblick in molekulare Prozesse im Bereich der heterogenen Organometallkatalyse zum Ziel.…”

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Direkte Beobachtung alternativer Reaktionswege an einzelnen Molekülen

et al. 2013

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Wir danken der Deutschen Forschungsgemeinschaft (DFG) für finanzielle Unterstützung (EXC81, SFB623), Stephen Hashmi (Universität Heidelberg) für hilfreiche Diskussionen, Volker Huch für die rçntgenkristallographische Charakterisierung sowie Michael Schwering und Dominik Brox, die das Projekt mit ihrem Fachwissen in Mikroskopie unterstützt haben. Hintergrundinformationen zu diesem Beitrag sind im WWW unter

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Probing Photocatalytic Active Sites on a Single Titanosilicate Zeolite with a Redox‐Responsive Fluorescent Dye

Cited by 18 publications

References 22 publications

Superresolution fluorescence mapping of single-nanoparticle catalysts reveals spatiotemporal variations in surface reactivity

Superresolution fluorescence mapping of single-nanoparticle catalysts reveals spatiotemporal variations in surface reactivity

“Extracting” the Key Fragment in ETS‐10 Crystallization and Its Application in AM‐6 Assembly

Direkte Beobachtung alternativer Reaktionswege an einzelnen Molekülen

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