Fluorine ions-mediated morphology control of anatase TiO2 with enhanced photocatalytic activity

Lv, Kangle; Cheng, Bei; Liu, Gang

doi:10.1039/c2cp23461k

Cited by 206 publications

(136 citation statements)

References 137 publications

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“…The majority of exposed facets of anatase TiO 2 are normally (1 0 1) due to it having the lowest surface energy under common conditions. In controllable synthesis of TiO 2 with exposed (0 0 1) facets, fluorine has been commonly used as a morphology-controlling agent to lower the surface energy in order to expose the reactive (0 0 1) facets [23,32,33]. Anatase TiO 2 with a high percentage of the reactive (0 0 1) facets has exhibited excellent photoreactivity, even much better than pure anatase TiO 2 or commercial P25 in photocatalytic reactions, such the oxidation of acetone [23], OH radical generation [24] and the degradation of methylene orange (MO) [34] and methylene blue (MB) [35], etc.…”

Section: Introductionmentioning

confidence: 99%

Photocatalytic oxidation of gaseous ammonia over fluorinated TiO2 with exposed (001) facets

et al. 2014

Applied Catalysis B: Environmental

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a b s t r a c tA surface-fluorinated TiO 2 (F-TiO 2 ) catalyst was synthesized by a hydrothermal method using hydrofluoric acid (HF) solution as a capping agent, and defluorinated TiO 2 (D-TiO 2 ) was next obtained by washing the F-TiO 2 with NaOH solution. The as-prepared catalysts were tested for the photocatalytic oxidation (PCO) of gaseous NH 3 under UV light. The F-TiO 2 catalyst exhibited remarkable activity for NH 3 removal, about twice as high as that of the commercial catalyst P25. In contrast, D-TiO 2 showed an obvious decrease in PCO activity. The catalysts were characterized by X-ray diffractometry (XRD), Brunauer-Emmett-Teller (BET) adsorption analysis, High-resolution Transmission electron microscopy (HR-TEM), and X-ray photoelectron spectroscopy (XPS). The results showed that the surface fluorination process formed the surface Ti-F group and also increased the percentage of reactive (0 0 1) facets to about 50%; the surface defluorination removed the fluorine (F) element from the F-TiO 2 surface but showed no influence on the percentage of reactive (0 0 1) facets. By comparing the specific activities of the catalysts, we found that both the active (0 0 1) facets and the surface Ti-F group contributed to the improvement of the PCO activity, while the surface Ti-F group plays the dominant role. The Ti-F group could retard the recombination of photogenerated electrons and holes, which is possibly the major reason for the excellent activity of the F-TiO 2 catalyst.

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Section: Introductionmentioning

confidence: 99%

Photocatalytic oxidation of gaseous ammonia over fluorinated TiO2 with exposed (001) facets

et al. 2014

Applied Catalysis B: Environmental

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“…As already stated, much effort has been focused on developing new routes for preparing {001} facets dominated anatase TiO 2 single crystals. 3,[7][8][9][10][11][12][13][14][15][16][17] There are different synthesis paths to produce TiO 2 crystals, such as trough titanate nanotubes (TNTs) in supercritical water. The transformation of the TNTs into anatase nanocrystals was achieved by two simultaneous processes (dissolution-nucleation and crystal growth while the other is an in situ nucleation and crystal growth).…”

Section: Introductionmentioning

confidence: 99%

“Crystallographic” holes: new insights for a beneficial structural feature for photocatalytic applications

et al. 2015

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One of the most fundamental aspects of the heterogeneous catalysis field is the manipulation of the catalysts' activity. In photocatalysis this is carried out by maximizing the right crystal plane of a semiconductor oxide. Until now, most of the papers have achieved this by a combination of different oxides, with noble metals and sometimes with carbon nanomaterials. In this work MWCNTs (multiwalled carbon nanotubes) were applied as "crystallization promoters" in a very simple, safe, one-step hydrothermal method. By this method TiO 2 nano/micro crystals with exposed {001} facets were obtained in the first step. The next episode in the crystal manipulation "saga" was the modification of the (001) crystallographic plane's structure by creating ordered/own faceted "crystallographic holes". These elements are capable of further enhancing the obtained activity of titania microcrystals to a higher extent, as shown by the UV driven photocatalytic phenol degradation experiments. The appearance of the holes was "provoked" by simple calcination and their presence and influence were demonstrated by XPS and HRTEM.

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“…The lifetime of the positrons in this state is known as bulk lifetime, which denotes as the τ b =139 for pristine TiO 2 , and the fast para-positronium annihilation (125 ps) has little effect owing to the low intensity of τ 3 (0∼0.2%). 8,11,12 The longer lifetime component τ 2 is assigned to the positrons captured by defects of larger size, such as vacancy clusters, grain boundary holes, etc. And the longest component τ 3 is probably assigned to the annihilation of orthopositronium atoms formed in the large voids (nanoscale) in materials.…”

Section: Resultsmentioning

confidence: 99%

“…The photo-induced electrons and holes can freely move, recombine or migrate to the surface and participate in the photocatalytic reactions as triggers. [4][5][6] Scotti et al, 7 Lv et al 8 and Jiang et al 9 proposed that the key role in controlling TiO 2 photocatalytic reactivity was to adjust the rate of the electron and hole recombination. Thompson et al 10 figured that some lattice defects could turn into the surface light activation points.…”

Section: Introductionmentioning

confidence: 99%

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Lattice distortion mechanism study of TiO2 nanoparticles during photocatalysis degradation and reactivation

Xue

Jiang

et al. 2015

AIP Advances

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In this paper, the photocatalytic process of TiO2 (P25) is directly characterized by using a positron annihilation lifetime spectroscopy (PALS), high-resolution transmission electron microscopy (HRTEM), Photoluminescence spectroscopy (PL) and UV Raman spectroscopy (Raman). The experimental results reveal that: 1) From PALS measurements, because τ1 and τ2 values and their intensity (I1 and I2) assigned to the different size and amounts of defects, respectively, their variations indicate the formation of different types and amounts of defects during the absorption and degradation. 2) HRTEM observations show that the lattice images become partly blurring when the methylene blue is fully degradated, and clear again after exposed in the air for 30 days. According to the results, we propose a mechanism that the lattice distortion induces the defects as electron capture sites and provides energy for improving photocatalytic process. Meanwhile, the lattice distortion relaxation after exposing in the air for 30 days perfectly explains the gradual deactivation of TiO2, because the smaller vacancy defects grow and agglomerate through the several photocatalytic processes. The instrumental PL and Raman are also used to analyze the samples and approved the results of PALS and HRTEM.

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Fluorine ions-mediated morphology control of anatase TiO2 with enhanced photocatalytic activity

Cited by 206 publications

References 137 publications

Photocatalytic oxidation of gaseous ammonia over fluorinated TiO2 with exposed (001) facets

Photocatalytic oxidation of gaseous ammonia over fluorinated TiO2 with exposed (001) facets

“Crystallographic” holes: new insights for a beneficial structural feature for photocatalytic applications

Lattice distortion mechanism study of TiO2 nanoparticles during photocatalysis degradation and reactivation

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