Anatase and rutile in evonik aeroxide P25: Heterojunctioned or individual nanoparticles?

Jiang, Xiongzhen; Manawan, Maykel; Feng, Ting; Qian, Ruifeng; Zhao, Ting; Zhou, Guanda; Kong, Fantai; Wang, Qing; Dai, Songyuan; Pan, Jia Hong

doi:10.1016/j.cattod.2017.06.010

Cited by 171 publications

(98 citation statements)

References 32 publications

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“…A /b was confirmed to be a mixed-phase nanoTiO 2 with approximate composition percentage ratios: 60% anatase, 35% brookite and 5% rutile; the B /r to have 60% brookite, 30% rutile, 10% anatase; the R /b to consist of 60% rutile, Catalysts 2020, 10, 407 5 of 18 40% brookite. For comparison, P25 was also analyzed ( Figure 2d) and found to consist of 80% anatase and 20% rutile, in agreement with other reports [15]. Despite the inclusion of a third component in the deconvolution analysis, the Raman-derived percentage compositions are in good overall agreement with the respective XRD data as presented in Table 1. assigned to the B1g, A1g or B1g and Eg Raman vibration modes of the anatase phase, respectively [34,35]; the 410, 585, 637 and 685 cm −1 Raman peaks to A1g, B2g and A1g modes of the brookite phase; while the 445 and 610 cm −1 to the A1g and B1g modes of the rutile phase [4,9,24,36].…”

Section: Nanostructural Propertiessupporting

confidence: 87%

“…Strategies to overcome these disadvantages and improve the photocatalytic efficiency involve (i) the modification of nanoTiO 2 by doping to broaden the spectrum wavelength [11][12][13] and (ii) the modifications of the structural and morphological characteristics which would give a beneficial synergistic effect between the TiO 2 polymorphs [14]. Though recently there is a controversy in literature as to which one has greater effect on the photocatalytic efficiency of the nanoTiO 2 [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

“…Nowadays, a lot of attention is given to mixed phase TiO 2 photocatalysts as the synergistic effect between the two phases reduces the recombination effect [4]. The most common commercial TiO 2 photocatalyst is the benchmark Evonik P25, which is a mixed phase of 80% A/20% R [15]. Even though many agree on the synergistic effect between the two phases that gives less e − cb and h + vb recombination, uncertainty exists, if the high photocatalytic efficiency is due to intra-particle heterojunction between the two phases or it is due to inter-particle contact of single phase nanoparticles [8,10,14,15,[21][22][23].…”

Section: Introductionmentioning

confidence: 99%

“…Even though many agree on the synergistic effect between the two phases that gives less e − cb and h + vb recombination, uncertainty exists, if the high photocatalytic efficiency is due to intra-particle heterojunction between the two phases or it is due to inter-particle contact of single phase nanoparticles [8,10,14,15,[21][22][23]. Ohtani et al argue that P25 is a simple mixture of A-R nanoparticles without any intrinsic electronic interactions [10], while Jiang et al although agree that P25 comprises single phase A and R particles, they also state that it comprises as well binary-phase heterojunctioned TiO 2 nanoparticles in the form of A particles having a thin R surface overlayer [15]. Observations were made by Likodimos et al that mixed-phase TiO 2 nanoparticles are significantly better photocatalysts than simple mixture of single-phase nanoparticles due to their close-contact heterophase junctions [4].…”

Section: Introductionmentioning

confidence: 99%

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Tunable Composition Aqueous-Synthesized Mixed-Phase TiO2 Nanocrystals for Photo-Assisted Water Decontamination: Comparison of Anatase, Brookite and Rutile Photocatalysts

et al. 2020

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Mixed-phase nanoTiO 2 materials attract a lot of attention as advanced photocatalysts for water decontamination due to their intrinsic structure that allows better photo-excited e − cb -h + vb charge separation, hence improved photocatalytic efficiency. Currently, the best-known mixed-phase TiO 2 photocatalyst is P25 with approximate composition 80% Anatase/20% Rutile (A /r ). Apart from Anatase (A) and Rutile (R) phases, there is Brookite (B) which has been evaluated less as photocatalyst in mixed-phase nanoTiO 2 systems. In this work we present a sustainable solution process to synthesize tunable composition mixed-phase nanotitania photocatalysts in a continuously stirred tank reactor (CSTR) by modulating conditions like pH, C TiCl4 and time. In particular three mixed-phase TiO 2 nanomaterials were produced, namely one predominantly anatase with brookite as minor component (A /b ), one predominantly brookite with minor component rutile (B /r ), and one predominantly rutile with minor component brookite (R /b ) and evaluated as photocatalysts in the degradation of methyl orange. The three semiconducting nanomaterials were characterized by XRD and Raman spectroscopy to quantify the phase ratios and subjected to nano-morphological characterization by FE-SEM and TEM/HR-TEM. The new mixed-phase nanoTiO 2 materials are shown to be endowed with large specific surface area, ranging from 90-125 m 2 g −1 , double of that of P25, to be mesoporous and be surface-rich in Ti-OH molecular groups varying from 12%-20% versus 4% for P25. These properties though impact the adsorptive capacity with R /b and B /r removing > 50% of MO but not photocatalytic activity. The latter depends on nanograined mixed-phase structure and not mere assembly of different phase nanoparticles. First-order rate constants reveal essentially equivalent photocatalytic activity for anatase nanocrystals with either rutile (P25) or brookite (this work) domains.

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Section: Nanostructural Propertiessupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Tunable Composition Aqueous-Synthesized Mixed-Phase TiO2 Nanocrystals for Photo-Assisted Water Decontamination: Comparison of Anatase, Brookite and Rutile Photocatalysts

et al. 2020

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“…In 1991, Bickley et al proposed that the high activity of P25 (and other mixed-phase titania photocatalysts) was caused by the enhancement in "the magnitude of the space-charge potential", as a result of the interface between different phases and localized electronic states in amorphous titania [82]. Although it is unclear who first used the term "synergy" (or "synergistic effect") between anatase and rutile to explain the high activity of P25, many reports have used it interchangeably for an interparticle electron transfer (IPCT) between polymorphs in P25 and other mixed-phase titania photocatalysts [86,[95][96][97][98]. However, commonly, no experimental evidence has been shown, and "synergy" has been only speculated based on the results showing a higher activity of mixed-phase titania than that of the single phase one.…”

Section: Photocatalytic Activity Of Titania Polymorphsmentioning

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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Selective Oxidation of 5‐Hydroxymethylfurfural to 2,5‐Diformylfuran by Visible Light‐Driven Photocatalysis over In Situ Substrate‐Sensitized Titania

et al. 2021

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Solar energy‐driven processes for biomass valorization are priority for the growing industrialized society. To address this challenge, efficient visible light‐active photocatalyst for the selective oxidation of biomass‐derived platform chemical is highly desirable. Herein, selective oxidation of 5‐hydroxymethylfurfural (HMF) to 2,5‐diformylfuran (DFF) was achieved by visible light‐driven photocatalysis over titania. Pristine titania is photocatalytically inactive under visible light, so an unconventional approach was employed for the visible light (λ=515 nm) sensitization of titania via a formation of a visible light‐absorbing complex of HMF (substrate) on the titania surface. Surface‐complexation of HMF on titania mediated ligand‐to‐metal charge transfer (LMCT) under visible light, which efficiently catalyzed the oxidation of HMF to DFF. A high DFF selectivity of 87 % was achieved with 59 % HMF conversion after 4 h of illumination. The apparent quantum yield obtained for DFF production was calculated to be 6.3 %. It was proposed that the dissociative interaction of hydroxyl groups of HMF and the titania surface is responsible for the surface‐complex formation. When the hydroxyl groups of titania were modified via surface‐fluorination or calcination the oxidation of HMF was inhibited under visible light, signifying that hydroxyl groups are decisive for photocatalytic activity.

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Anatase and rutile in evonik aeroxide P25: Heterojunctioned or individual nanoparticles?

Cited by 171 publications

References 32 publications

Tunable Composition Aqueous-Synthesized Mixed-Phase TiO2 Nanocrystals for Photo-Assisted Water Decontamination: Comparison of Anatase, Brookite and Rutile Photocatalysts

Tunable Composition Aqueous-Synthesized Mixed-Phase TiO2 Nanocrystals for Photo-Assisted Water Decontamination: Comparison of Anatase, Brookite and Rutile Photocatalysts

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

Selective Oxidation of 5‐Hydroxymethylfurfural to 2,5‐Diformylfuran by Visible Light‐Driven Photocatalysis over In Situ Substrate‐Sensitized Titania

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