Characterization and mechanistic study of Mo+6 and V+5 codoped TiO2 as a photocatalyst

Khan, Hizbullah; Berk, Dimitrios

doi:10.1016/j.jphotochem.2014.08.007

Cited by 64 publications

(35 citation statements)

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“…In spite of the extensive reports on cationic and anionic doping of TiO 2 , the visible photocatalytic activity has remained quite low, because monodoping can generate recombination centers for the photoinduced electrons and holes inside the TiO 2 [14]. To overcome the problem of electron-hole recombination, researchers tried codoping of TiO 2 with both metals and nonmetals, and the results showed enhanced electron-hole separation and increased absorption of photons in the visible range leading to enhanced photocatalytic activity of codoped TiO 2 against the degradation of aqueous organic compounds [15,16].…”

Section: Introductionmentioning

confidence: 99%

Chelated Nitrogen-Sulphur-Codoped TiO₂: Synthesis, Characterization, Mechanistic, and UV/Visible Photocatalytic Studies

Khan

Swati

Younas

et al. 2017

International Journal of Photoenergy

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This study presents in detail the physicochemical, photoluminescent, and photocatalytic properties of carboxylic acid chelated nitrogen-sulphur-codoped TiO 2 . From the Fourier transform infrared spectroscopic study, it was revealed that the formate group formed bidentate bridging linkage while the acetate group coordinated in a bidentate chelating mode with a titanium precursor. In compliance with X-ray diffraction data, the anatase to rutile transformation temperature was extended due to carboxylic acid chelation and NS codoping. Raman analysis indicated four Raman peaks at 146, 392, 512, and 632 cm −1 for the precalcined chelated TiO 2 ; on incorporation with NS dopants, an increase in Raman intensity for these peaks was recorded, indicating the structure stability of the anatase phase. Furthermore, X-ray photoelectron spectroscopic study revealed the presence of anionic doping of nitrogen and cationic doping of sulphur in the lattice of TiO 2 . When evaluating the UV-visible photodegradation rate of 4-chlorophenol, the modified TiO 2 (NS 0.06 -TFA) showed the highest photocatalytic activity. In connection with the activity tests, several scavenger agents were employed to elucidate the significance of the different reactive oxidizing species during the photocatalytic process. Moreover, the transfer pathways of photogenerated carriers and the photocatalytic reaction mechanism of modified TiO 2 were also explained in detail.

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Section: Introductionmentioning

confidence: 99%

Chelated Nitrogen-Sulphur-Codoped TiO₂: Synthesis, Characterization, Mechanistic, and UV/Visible Photocatalytic Studies

Khan

Swati

Younas

et al. 2017

International Journal of Photoenergy

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“…Khan and Berk suggested that an impurity level of Mo 6+ /Mo 5+ (Mo 6+ 4d 0 1e -→Mo 5+ 4d 1 ) could be generated below the conduction band (CB) of TiO 2 . During photoexcitation, electron transition could occur from the 0 2p valence band (VB) of TiO 2 into the Mo 6+ /Mo 5+ impurity level and then to the CB of TiO 2 through d(Mo 5+ )-d(Ti) transition [38]. The photo-induced electrons could initiate the reduction of Ti 4+ ions to Ti 3+ states at the surface.…”

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confidence: 99%

Mo doped TiO₂: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

et al. 2020

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This work outlines an experimental and theoretical investigation of the effect of molybdenum (Mo) doping on the oxygen vacancy formation and photocatalytic activity of TiO 2 . Analytical techniques such as x-ray diffraction (XRD), Raman, x-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) were used to probe the anatase to rutile transition (ART), surface features and optical characteristics of Mo doped TiO 2 (Mo-TiO 2 ). XRD results showed that the ART was effectively impeded by 2 mol% Mo doping up to 750°C, producing 67% anatase and 33% rutile. Moreover, the crystal growth of TiO 2 was affected by Mo doping via its interaction with oxygen vacancies and the Ti-O bond. The formation of Ti-O-Mo and Mo-Ti-O bonds were confirmed by XPS results. Phonon confinement, lattice strain and non-stoichiometric defects were validated through the Raman analysis. DFT results showed that, after substitutional doping of Mo at a Ti site in anatase, the Mo oxidation state is Mo 6+ and empty Mo-s states emerge at the titania conduction band minimum. The empty Mo-d states overlap the anatase conduction band in the DOS plot. A large energy cost, comparable to that computed for pristine anatase, is required to reduce Mo-TiO 2 through oxygen vacancy formation. Mo 5+ and Ti 3+ are present after the oxygen vacancy formation and occupied states due to these reduced cations emerge in the energy gap of the titania host. PL studies revealed that the electron-hole recombination process in Mo-TiO 2 was exceptionally lower than that of TiO 2 anatase and rutile. This was ascribed to introduction of 5s gap states below the CB of TiO 2 by the Mo dopant. Moreover, the photo-generated charge carriers could easily be trapped and localised on the TiO 2 surface by Mo 6+ and Mo 5+ ions to improve the photocatalytic activity. coatings [8,9]. The most commonly existing crystalline polymorphs of TiO 2 are anatase, rutile and brookite [10][11][12]. Anatase is accepted to be the more active phase of TiO 2 and is preferred by the ceramic industries to fabricate light active antimicrobial indoor building materials such as ceramics, glass, tiles and sanitary surfaces [13,14]. This requires thermal stability of the anatase phase under typical ceramic processing conditions. TiO 2 anatase is mainly fabricated at low calcination temperatures (∼500°C) to prevent the anatase to rutile phase transition (ART) [15][16][17], which produces the less photo-active rutile phase. The photo-activity of anatase arises from its appropriate band edge positions, electron affinity, ionisation potential, and the long lifetime of charge carriers [10,12,18]. Moreover, transient photo-conductance analysis has revealed that the electron-hole recombination phenomena in anatase (101) phase is much slower compared to rutile (110), which is credited in part to the indirect band gap of anatase [11,19].The unit cells of anatase and rutile phases are composed of TiO 6 octahedra with titanium atoms at the centre and oxygen atoms at the vertices [20]. Both anatase and rutile have a t...

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“…Tetrabutyl titanate (Ti(OBu) 4 ) and cumene hydroperoxide (CHP) were purchased from J&K Chemical Ltd. Octane, concentrated hydrochloric acid, methanol, ethanol and isopropanol in the analytical grade were purchased from Fuchen Chemical Plant in Tianjin, China. DBT was purchased from Acros Organics.…”

Section: Materials and Chemicalsmentioning

confidence: 99%

“…The transparent capillary was treated with alkaline solution (10 wt.% NaOH aqueous solution) at 413 K for 5 h before coating, and then washed several times with deionized water before further use. In a typical run, 12.5 mL of Ti(OBu) 4 was added to 33.3 mL of ethanol and the solution was stirred for 10 min. Then a certain amount of concentrated hydrochloric acid was added and stirred for another 30 min.…”

Section: Surface Modification Of Microchannel Reactormentioning

confidence: 99%

“…TiO 2 -based catalysts have been recognized as the most promising catalyst for photo-catalytic synthesis, photo-degradation of contaminated water and even photo-oxidation of organosulfur compounds in fuels, owning to their excellent properties such as high light-conversion efficiency, chemical stability, nontoxic nature and low cost [1][2][3][4][5][6][7][8][9][10]. Commercial TiO 2 catalysts are typically available in suspension mode (for example, Degussa P25 powder) or immobilized on a substrate.…”

Section: Introductionmentioning

confidence: 99%

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Glass capillaries with TiO 2 supported on inner wall as microchannel reactors

Shen

Wang

et al. 2015

Chemical Engineering Journal

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Characterization and mechanistic study of Mo+6 and V+5 codoped TiO2 as a photocatalyst

Cited by 64 publications

References 35 publications

Chelated Nitrogen-Sulphur-Codoped TiO₂: Synthesis, Characterization, Mechanistic, and UV/Visible Photocatalytic Studies

Chelated Nitrogen-Sulphur-Codoped TiO₂: Synthesis, Characterization, Mechanistic, and UV/Visible Photocatalytic Studies

Mo doped TiO₂: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

Glass capillaries with TiO 2 supported on inner wall as microchannel reactors

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Characterization and mechanistic study of Mo+6 and V+5 codoped TiO2 as a photocatalyst

Cited by 64 publications

References 35 publications

Chelated Nitrogen-Sulphur-Codoped TiO2: Synthesis, Characterization, Mechanistic, and UV/Visible Photocatalytic Studies

Chelated Nitrogen-Sulphur-Codoped TiO2: Synthesis, Characterization, Mechanistic, and UV/Visible Photocatalytic Studies

Mo doped TiO2: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

Glass capillaries with TiO 2 supported on inner wall as microchannel reactors

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Product

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About

Chelated Nitrogen-Sulphur-Codoped TiO₂: Synthesis, Characterization, Mechanistic, and UV/Visible Photocatalytic Studies

Chelated Nitrogen-Sulphur-Codoped TiO₂: Synthesis, Characterization, Mechanistic, and UV/Visible Photocatalytic Studies

Mo doped TiO₂: impact on oxygen vacancies, anatase phase stability and photocatalytic activity