W and Mo doped TiO2: Synthesis, characterization and photocatalytic activity

Avilés-García, Osmín; Valencia, Jaime Espino; Romero, Rubı́; Rico-Cerda, José Luis; Arroyo-Albiter, Manuel; Natividad, Reyna

doi:10.1016/j.fuel.2016.10.005

Cited by 82 publications

(57 citation statements)

References 43 publications

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“…This is ascribed to high electronegativity of Mo compared to Ti, suggesting a lattice shift by the substitution of Mo 6+ for Ti 4+ ion [34]. Oxygen vacancies would also be created by this kind of replacement [34,68], however, this was not observed in our DFT calculations. Moreover, Mo ions may strongly interact with oxygen atoms or oxygen vacancies via chemical bonds in the anatase crystal lattice, suggesting the formation of structural defects such as Ti-O-Mo and Mo-Ti-O bonds by Mo doping [35].…”

Section: Xpsmentioning

confidence: 70%

“…Ti 2p, O 1s, Mo 3d scans of pure TiO 2 (0 mol% Mo-TiO 2 at 500°C) and 2 mol% Mo-TiO 2 at 750°C are displayed in figure 4. The representative spin-orbit coupling of Ti 2p peaks such as Ti 2p 3/2 and Ti 2p 1/2 are observed at 458.86 eV and 464.53 eV, respectively (figure 4(a)) [68,69]. This is ascribed to the existence of titanium in Ti 4+ state.…”

Section: Xpsmentioning

confidence: 94%

“…The peak located at 530.03 eV is attributed to lattice oxygen in Ti-O bond of TiO 2 [69]. The surface O-H group of TiO 2 is detected around 531.94 eV ( figure 4(b)) [68,69]. The peak positions of Ti 2p and O 1s are slightly increased for 2 mol% Mo-TiO 2 compared to pure TiO 2 (figures 4(c) and (d)).…”

Section: Xpsmentioning

confidence: 95%

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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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Section: Xpsmentioning

confidence: 70%

Section: Xpsmentioning

confidence: 94%

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

et al. 2020

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“…The photodegradation follows a pseudofirst-order reaction with observed rate constants regrouped in Table 5. The heterojunction between three different phases rutile, anatase, and W y Ti 1-y O 2 ensures a good separation of charge carriers, which can be due to the presence of different oxidation states W 6+ , W 5+ , and W 4+ as reported by Tian et al and Avilés-Garcia et al [47,48] It was also reported that when irradiated, W 5+ sites as photosensitive sites can induce one electron out from the low-valence W 5+ site and then this W 5+ will convert to W 6+ and release one elecron according to the Equation (1). Figure 8 summarizes the results of these experiments.…”

Section: Photocatalytic Activitymentioning

confidence: 83%

Synthesis of W‐doped TiO₂ by low‐temperature hydrolysis: Effects of annealing temperature and doping content on the surface microstructure and photocatalytic activity

Moslah

Aguilar

Alcántara

et al. 2018

J Chinese Chemical Soc

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A series of tungsten‐doped Titania photocatalysts were synthesized using a low‐temperature method. The effects of dopant concentration and annealing temperature on the phase transitions, crystallinity, electronic, optical, and photocatalytic properties of the resulting material were studied. The X‐ray patterns revealed that the doping delays the transition of anatase to rutile to a high temperature. A new phase WyTi1‐yO2 appeared for 5.00 wt% W‐TiO2 annealed at 900 °C. Raman and diffuse reflectance UV–Vis spectroscopy showed that band gap values decreased slightly up to 700 °C. X‐ray photoelectron spectroscopy showed that surface species viz. Ti3+, Ti4+, O2−, oxygen‐vacancies, and adsorbed OH groups vary depending on the preparation conditions. The photocatalytic activity was evaluated via the degradation of methylene blue using LED white light. The degradation rate was affected by the percentage of dopants. The best photocatalytic activity was achieved with the sample labeled 5.00 wt% W‐TiO2 annealed at 700 °C.

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“…Li et al [15] reported a novel Ni-doped TiO 2 inverse opal photonic microarray (IOPM) structure photocatalyst and Ni doping could increase the visible light absorption. Recent studies indicate that the radius of Mo 6+ is similar to that of Ti 4+ , thus, compared with other transition metal elements, Mo can effectively replace Ti 4+ in TiO 2 crystal lattice [18,19]. The doping donates a contribution to redshift as the absorption edge moving towards the region of visible light and improve the light response under both ultraviolet and visible light as well, enhancing the photoelectrochemical activity of TiO 2 [7,18].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Photoelectrochemical Properties from Mo-Doped TiO2 Nanotube Arrays Film

Xue

Luo

et al. 2020

Coatings

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Mo-doped TiO2 nanotube arrays are prepared successfully by a combined method of direct current (DC) magnetron sputtering and anodic oxidation. The doping amount of Mo can be modified by changing the number of molybdenum blocks on the Ti target while a Ti–Mo alloy film is prepared by magnetron sputtering on a metal Ti substrate, following a Mo-doped TiO2 nanotube array grown by anodization. Morphology test shows that the doping of Mo could inhibit the phase transition and growth of crystal of TiO2. X-ray photoelectron spectroscopy (XPS) results show that Mo has successfully been embedded in the TiO2 crystal lattice and mainly exists in the valence states of Mo6+. Mo-doping samples show slightly increased visible light absorption as the red shift of TiO2 absorption edge with the band gap dropping from 3.24 to 3.16 eV with 0.5 at.% Mo doping. The enhanced photocurrent is demonstrated for a 0.5 at.% Mo-doped TiO2 electrode. Through photoelectric performance testing under UV-visible light irradiation, the nanotube array film with a Mo-doped content of 0.5% produced the maximum photocurrent density, which is about four times the undoped TiO2 nanotube array film, exhibiting a considerable photoelectric effect gain. The controllable Mo doping TiO2 nanotube array film prepared by this combining technique is expected as a promising material for efficient applications in photoelectric conversion.

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W and Mo doped TiO2: Synthesis, characterization and photocatalytic activity

Cited by 82 publications

References 43 publications

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

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

Synthesis of W‐doped TiO₂ by low‐temperature hydrolysis: Effects of annealing temperature and doping content on the surface microstructure and photocatalytic activity

Enhanced Photoelectrochemical Properties from Mo-Doped TiO2 Nanotube Arrays Film

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W and Mo doped TiO2: Synthesis, characterization and photocatalytic activity

Cited by 82 publications

References 43 publications

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

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

Synthesis of W‐doped TiO2 by low‐temperature hydrolysis: Effects of annealing temperature and doping content on the surface microstructure and photocatalytic activity

Enhanced Photoelectrochemical Properties from Mo-Doped TiO2 Nanotube Arrays Film

Contact Info

Product

Resources

About

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

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

Synthesis of W‐doped TiO₂ by low‐temperature hydrolysis: Effects of annealing temperature and doping content on the surface microstructure and photocatalytic activity