Titania aerogels: Preparation and photocatalytic tests

Malinowska, B; Walendziewski, Jerzy; Robert, Didier; Weber, J.V.; Stolarski, Marek

doi:10.1155/s1110662x03000266

Cited by 26 publications

(13 citation statements)

References 18 publications

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“…Titania aerogels are very interesting nano/microstructures, due to their low density, porosity, high pore volume, and large specific surface area [160][161][162][163]. Although they are commonly composed of NPs of titania, the resultant aerogel structure is much larger, and thus titania aerogels might be classified as 3D structures.…”

Section: Titania Aerogelsmentioning

confidence: 99%

Morphology- and Crystalline Composition-Governed Activity of Titania-Based Photocatalysts: Overview and Perspective

et al. 2019

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Titania photocatalysts have been intensively examined for both mechanism study and possible commercial applications for more than 30 years. Although various reports have already been published on titania, including comprehensive review papers, the morphology-governed activity, especially for novel nanostructures, has not been reviewed recently. Therefore, this paper presents novel, attractive, and prospective titania photocatalysts, including zero-, one-, two-, and three-dimensional titania structures. The 1D, 2D, and 3D titania structures have been mainly designed for possible applications, e.g., (i) continuous use without the necessity of particulate titania separation, (ii) efficient light harvesting (e.g., inverse opals), (iii) enhanced activity (fast charge carriers' separation, e.g., 1D nanoplates and 2D nanotubes). It should be pointed out that these structures might be also useful for mechanism investigation, e.g., (i) 3D titania aerogels with gold either incorporated inside the 3D network or supported in the porosity, and (ii) titania mesocrystals with gold deposited either on basal or lateral surfaces, for the clarification of plasmonic photocatalysis. Moreover, 0D nanostructures of special composition and morphology, e.g., magnetic(core)-titania(shell), mixed-phase titania (anatase/rutile/brookite), and faceted titania NPs have been presented, due to their exceptional properties, including easy separation in the magnetic field, high activity, and mechanism clarification, respectively. Although anatase has been usually thought as the most active phase of titania, the co-existence of other crystalline phases accelerates the photocatalytic activity significantly, and thus mixed-phase titania (e.g., famous P25) exhibits high photocatalytic activity for both oxidation and reduction reactions. It is believed that this review might be useful for the architecture design of novel nanomaterials for broad and diverse applications, including environmental purification, energy conversion, synthesis and preparation of "intelligent" surfaces with self-cleaning, antifogging, and antiseptic properties.

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Section: Titania Aerogelsmentioning

confidence: 99%

Morphology- and Crystalline Composition-Governed Activity of Titania-Based Photocatalysts: Overview and Perspective

et al. 2019

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“…10 Ismail et al posited that networked, mesoporous TiO 2 modified with gold (Au) nanoparticles strongly enhanced UV-photocatalytic oxidation of methanol because electrons traveled over multiple nanoparticle lengths to reach the Au nanoparticles. 11 In these and other examples of photocatalysis at networked nanostructured titania, 12,13,14,15,16,17,18,19 the fundamental effects of electron (and hole) lifetime as well as electron mobility on photocatalytic activity remain open. In order to exploit the promise of a wired photocatalytic system, the dynamics of the charge carriers in the semiconductor network must be more rigorously understood.…”

mentioning

confidence: 99%

Correlating Changes in Electron Lifetime and Mobility on Photocatalytic Activity at Network-Modified TiO₂ Aerogels

DeSario¹,

Pietron²,

Taffa

et al. 2015

J. Phys. Chem. C

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We use intensity-modulated photovoltage spectroscopy (IMVS) and intensitymodulated photocurrent spectroscopy (IMPS) to characterize carrier dynamics in titania (TiO 2 ) aerogels under photocatalytic conditions. By systematically increasing the weight fraction of the sol-gel precursor during TiO 2 sol-gel synthesis, we are able to impart drastic changes in carrier transport/trapping and improve the photocatalytic activity of TiO 2 aerogels for two mechanistically divergent photochemical reactions-reductive water splitting (H 2 generation) and oxidative degradation of dichloroacetate (DCA). The lifetimes of photogenerated electrons increase in going from lowest-to-highest precursor concentrations, as measured by IMVS, indicating increasing site density for electron traps, a trend that correlates with an 8× improvement for photocatalytic H 2 generation. Electron mobility in the aerogel films, as measured by IMPS, decreases with increasing trap density, further implicating the trapping sites as reactive sites. In contrast, photocatalytic DCA degradation-driven primarily by direct hole transfer to adsorbed DCA-depends only weakly on the electron dynamics in the film. Transient infrared spectroscopy shows no difference in carrier decay amongst the aerogel samples on picosecond timescales, indicating that changes in carrier dynamics within these networked nanomaterials are only observable at timescales measured by IMPV and IMPS. Correlating holemediated and electron-mediated photocatalytic activity with direct measurement of electron dynamics under photocatalytically relevant conditions and timescales comprises a powerful approach to determine how synthetic modifications to networked nanostructured photocatalysts affect the relevant physicochemical phenomena underlying their photocatalytic performance.

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“…The supercrititical drying technique offers the possibility to vary the drying temperature and, hence, to tailor the specifications of the dried material. [57] In comparison with other media used in the supercritical drying procedure like acetone [58] or alcohols, [59,60,62] CO 2 is beneficial owing to its relatively mild supercritical conditions, especially the low supercritical temperature of 304.13 K. Recent investigations showed that supercritical drying leads to better results than, for instance, freeze-drying. CO 2 can be recycled easily; it is also non-flammable, non-toxic, and inexpensive.…”

Section: Synthesis Of the Aerogelsmentioning

confidence: 99%

Zirconia‐based Aerogels via Hydrolysis of Salts and Alkoxides: The Influence of the Synthesis Procedures on the Properties of the Aerogels

Schäfer

Brandt

Milow

et al. 2013

Chemistry An Asian Journal

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This contribution aims at evaluating different synthesis procedures leading to zirconia-based aerogels. A series of undoped and yttrium-doped zirconia aerogels have been prepared via hydrolysis and condensation reaction of different alkoxy- and different inorganic salt-based precursors followed by supercritical drying. Well-established but deleterious zirconium n-propoxide (TPOZ) or zirconium n-butoxide (TBOZ) were used as metal precursors in combination with acids like nitric acid and acetic acid as auxiliary agent for the generation of non-yttrium stabilized zirconia aerogels. Yttrium-stabilized zirconia aerogels as well as pure zirconia aerogels were obtained by the salt route starting from ZrCl4 and crosslinking agents like propylene oxide or acetylacetone. The characteristics of the products were analyzed by nitrogen adsorption measurements, electron microscopy, and X-ray scattering. It turned out that with respect to all relevant properties of the aerogels as well as the practicability of the synthesis procedures, approaches based on inexpensive non-toxic salt precursors are the methods of choice. The salt-based approaches allow not only for low-cost, easy-to-handle synthesis procedures with realizable gelation times of less than 60 seconds, but also delivered the products with the highest surface area (449 m(2) g(-1) for ZrCl4) within this series of syntheses.

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Titania aerogels: Preparation and photocatalytic tests

Cited by 26 publications

References 18 publications

Morphology- and Crystalline Composition-Governed Activity of Titania-Based Photocatalysts: Overview and Perspective

Morphology- and Crystalline Composition-Governed Activity of Titania-Based Photocatalysts: Overview and Perspective

Correlating Changes in Electron Lifetime and Mobility on Photocatalytic Activity at Network-Modified TiO₂ Aerogels

Zirconia‐based Aerogels via Hydrolysis of Salts and Alkoxides: The Influence of the Synthesis Procedures on the Properties of the Aerogels

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Titania aerogels: Preparation and photocatalytic tests

Cited by 26 publications

References 18 publications

Morphology- and Crystalline Composition-Governed Activity of Titania-Based Photocatalysts: Overview and Perspective

Morphology- and Crystalline Composition-Governed Activity of Titania-Based Photocatalysts: Overview and Perspective

Correlating Changes in Electron Lifetime and Mobility on Photocatalytic Activity at Network-Modified TiO2 Aerogels

Zirconia‐based Aerogels via Hydrolysis of Salts and Alkoxides: The Influence of the Synthesis Procedures on the Properties of the Aerogels

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Correlating Changes in Electron Lifetime and Mobility on Photocatalytic Activity at Network-Modified TiO₂ Aerogels