Surfactant-Assisted Elimination of a High Energy Facet as a Means of Controlling the Shapes of TiO<sub>2</sub> Nanocrystals

Jun, Young‐wook; Casula, Maria Francesca; Sim, Jae Hwan; Kim, Sang Youl; Cheon, Jinwoo; Alivisatos, A. Paul

doi:10.1021/ja0369515

Cited by 556 publications

(458 citation statements)

References 18 publications

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“…1a). The progression from Ostwald ripening to focusing to kinetic shape control was first seen in colloidal CdSe nanocrystals 32 , but subsequently has been observed in a variety of other systems, such as cobalt 33,34 and titanium dioxide 35 .…”

Section: Kinetic Shape Controlmentioning

confidence: 97%

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Colloidal nanocrystal synthesis and the organic–inorganic interface

Yin

Alivisatos

2004

Nature

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3,057

2,730

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Colloidal nanocrystals are sometimes referred to as 'artificial atoms' because the density of their electronic states-which controls many physical properties-can be widely and easily tuned by adjusting composition, size and shape. The combination of strongly size-and shape-dependent physical properties and ease of fabrication and processing makes nanocrystals promising building blocks for materials with designed functions 1,2 . But the ability to control the uniformity of the size, shape, composition, crystal structure and surface properties of the nanocrystals is not only of technological interest: having access to defined nanoscale structures is essential to uncovering their intrinsic properties unaffected by sample inhomogeneity. Rigorous understanding of the properties of individual nanocrystals enables exploitation of collective properties of nanocrystal ensembles, making it possible to design and fabricate novel electronic, magnetic and photonic devices and other functional materials based on these nanostructures.Colloidal nanocrystals with a semiconductor as the inorganic material-so-called quantum dots-exhibit size tunable band gaps and luminescence energies due to the quantum size effect 3 . This has led to their use as fluorescent biological labels 4-6 , with colloidal quantum dots now widely employed as targeted fluorescent labels in biomedical research applications. Compared to the organic fluorophores that have been used as biological labels previously, quantum dots are extremely bright and do not photo-bleach, and they provide a readily accessible range of colors. Other applications that could benefit from the combination of low-cost processing with solid-state performance include the use of colloidal quantum dots and rods as possible alternatives to semiconductor polymers in light emitting diodes 7 , lasers 8 , and solar cells 9 . The scope for these applications has prompted intensive study of the synthesis of these materials to optimize colloidal semiconductor nanocrystal fabrication. As a result, many new concepts for controlling the size, shape, and connectivity or coupling of colloidal nanocrystals have been developed first for these materials, but a unified set of synthesis control concepts is now also applied to other classes of materials such as metals and metal oxides. These materials will extend the range of potential applications for colloidal nanocrystals to many other areas, including catalysis.Over the last decade chemists have come to appreciate that from the point of view of synthesis, colloidal inorganic nanocrystals can be viewed as a class of macromolecule, with preparative strategies that are similar in many ways to those employed with artificial organic polymers. For nanocrystals of one to one hundred nanometers diameter, it is possible to define the average and the dispersion of the diameter, as well as the aspect ratio; the degree of precision with which the desired structure is realized is similar to what is achieved with synthetic polymers, where the preparative means at o...

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Section: Kinetic Shape Controlmentioning

confidence: 97%

“…This new intermediate energy facet will still grow more quickly than the initial slow growing one, so that the shape will evolve in a complex pattern during growth. This has been used to form arrow shaped nanocrystals of CdSe 22 and zigzag shaped crystals of TiO2 35 (Fig. 5).…”

Section: Kinetic Shape Controlmentioning

confidence: 99%

Colloidal nanocrystal synthesis and the organic–inorganic interface

Yin

Alivisatos

2004

Nature

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3,057

2,730

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“…Therefore, one of the reason of the low r(H 2 ) over mesoparticles containing octahedral crystallites is their relatively small SSA. In general, crystals are grown in the direction to minimize overall surface free energy and higher energy facets disappear along with an increase of crystalline size, 13,14 so that anatase particles with relatively small SSA would expose predominantly low index facets with small energy, e.g., {101} and {100}. In this regard, the relatively low r(H 2 ) over anatase particles with small SSA might be related to the property of {101} facets, which are likely exposed on well-grown crystallites.…”

Section: 4mentioning

confidence: 99%

Photocatalytic activity of octahedral single-crystalline mesoparticles of anatase titanium(iv) oxide

et al. 2009

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Octahedral titanium(IV) oxide (TiO 2 ) crystallites exposing anatase {101} facets exhibited relatively high photocatalytic activity for oxidative decomposition of organic compounds and low activity for hydrogen liberation in the absence of molecular oxygen probably due to the characteristics of anatase {101} surface.Anatase has been the most studied polymorph of TiO 2 owing to its higher photocatalytic activity for oxidative decomposition of organic compounds in the presence of molecular oxygen, 1,2 hydrogen (H 2 ) liberation, and so on. Surface free energy of anatase {101} lattice plane is reported to be the smallest among the other planes of anatase. 3,4In agreement with natural minerals, a truncated octahedral bipyramid, exposing eight {101} facets as well as two {001} facets, has been shown as a thermodynamically most stable shape of anatase crystallites based on Wulff construction. 3,4 In spite of the important applications of anatase TiO 2 , experimental studies on the photoactive property of singlecrystalline surface are still limited due to the difficulty to obtain high quality anatase samples. 5A few studies suggested the significant role of facets of TiO 2 polyhedral particles for photocatalytic reactions. 6,7 Recent development of hydrothermal reaction method has enabled to prepare anatase crystalline particles with well-developed facets in a relatively high yield. [8][9][10] The aim of the present study is to investigate the roles of {101} facets, which is the most likely observed on anatase mesoparticles, 11 for practical photocatalytic reaction system such as powder suspensions. In order to compare the

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“…The adsorbed species may change the relative stability of the different facets, or the growth rate in the different directions, thus altering the equilibrium shapes of anatase TiO 2 , resulting in a shape that, ideally, is uniquely determined by the nature and concentration of the adsorbates [19][20][21][22][23]. In this regard, preliminary theoretical work played an essential role in defining the expected optimal working conditions (including temperature and water partial pressure) to selectively obtain anatase TiO 2 crystals with specific surface facets [15].…”

Section: Introductionmentioning

confidence: 99%

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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Surfactant-Assisted Elimination of a High Energy Facet as a Means of Controlling the Shapes of TiO₂ Nanocrystals

Cited by 556 publications

References 18 publications

Colloidal nanocrystal synthesis and the organic–inorganic interface

Colloidal nanocrystal synthesis and the organic–inorganic interface

Photocatalytic activity of octahedral single-crystalline mesoparticles of anatase titanium(iv) oxide

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

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Surfactant-Assisted Elimination of a High Energy Facet as a Means of Controlling the Shapes of TiO2 Nanocrystals

Cited by 556 publications

References 18 publications

Colloidal nanocrystal synthesis and the organic–inorganic interface

Colloidal nanocrystal synthesis and the organic–inorganic interface

Photocatalytic activity of octahedral single-crystalline mesoparticles of anatase titanium(iv) oxide

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

Contact Info

Product

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Surfactant-Assisted Elimination of a High Energy Facet as a Means of Controlling the Shapes of TiO₂ Nanocrystals