The Role of Nb Addition in TiO<sub>2</sub> Nanoparticles: Phase Transition and Photocatalytic Properties

Silva, Luís F. da; Avansi, Waldir; Catto, Ariadne C.; Rodrigues, João Elias Figueiredo Soares; Bernardi, Maria Inês Basso; Mastelaro, Valmor Roberto

doi:10.1002/pssa.201800321

Cited by 8 publications

(5 citation statements)

References 83 publications

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“…ART of TiO 2 at high temperature could be controlled by the addition of metal ions, suitable chemical modifiers and an appropriate synthesis method [13]. Doping with metal ions is a one of the profitable ways to retard the ART [14,21,[23][24][25][26][27][28][29][30][31]. Metal ions could improve the thermal stability of TiO 2 through the reduction in contact points, and nucleation sites [32].Generally, doping of an element with higher oxidation state compared to Ti 4+ would improve charge carrier separation on the photocatalyst surface [33].…”

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

et al. 2020

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“…Schematic illustration of the proposed mechanism of selective adsorption of the cationic dye such as Malachite green onto the hybrid nanocomposite can be seen in Figure (a). Due to the Lewis acidity of niobium, it acts as an active site for the photo‐degradation thus enhancing the efficiency significantly while electron donating nature of silver nanocluster stabilized by captopril suppresses the self‐recombination rate . Electron rich silver nanocluster, TiO 2 and niobium oxide creates a ternary junction and due to the presence of ternary junction, electron‐hole pair recombination is strongly reduced.…”

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confidence: 99%

“…Visible light photocatalysis of the cationic dye (malachite green) by the hybrid nanocomposite is proposed by a schematic in Figure (b). As the band edge of both TiO 2 and Nb 2 O 5 are sufficiently close in energy, creation of a heterojunction between these nanomaterials does not change light absorption property and it allows the absorption of UV light only. However it promotes the interfacial charge transfer between these two and has been proven to improve the photocatalytic activity .…”

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confidence: 99%

Silver Nanocluster Anchored TiO₂/Nb₂O₅ Hybrid Nanocomposite as Highly Efficient and Selective Visible‐Light Sensitive Photocatalyst

2019

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It is of great interest to find a suitable modification of noble metal nanocluster (NC) with an aim to get a profound change in physical and chemical properties. In the present study, a new class of hybrid nanomaterials were successfully synthesized by anchoring Ag nanocluster with TiO 2 /Nb 2 O 5 nanocomposite. Two synthetic strategies have been carried out to prepare these. Two steps synthetic strategy was found to efficiently decorate TiO 2 /Nb 2 O 5 with silver nanocluster whereas one step synthesis produced Ag/TiO 2 nanocluster with negligible Nb 2 O 5 content. The as-prepared materials were characterized by HRTEM, EDAX, FTIR, Raman and XRD. Visible light photo-catalytic activities of the as-synthesized hybrid nanomaterials were investigated for the degradation of some of the potentially hazardous organic dyes (Malachite green and Methyl orange). We observed much greater photocatalytic activity of the nanocomposite for the degradation of Malachite green when silver nanocluster is anchored to the TiO 2 /Nb 2 O 5 as compared to the same materials with negligible Nb 2 O 5 content. Such observations indicate that the loading of Nb 2 O 5 in hybrid nanocomposite allowed the selective enhancement of the photocatalytic degradation of Malachite green.[a] Dr.

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“…cleaning coating for architectural glazing units 21,22 . This work focuses to prove the concept of combining HiPIMS in adjustable magnetic field configuration with a CVD to deposit metaldoped compounds.…”

Section: Introductionmentioning

confidence: 99%

Nb-doped TiO2 coatings developed by high power impulse magnetron sputtering-chemical vapor deposition hybrid deposition process

Kulczyk-Malecka

Donaghy

Delfour-Peyrethon

et al. 2020

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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The Role of Nb Addition in TiO₂ Nanoparticles: Phase Transition and Photocatalytic Properties

Cited by 8 publications

References 83 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

Silver Nanocluster Anchored TiO₂/Nb₂O₅ Hybrid Nanocomposite as Highly Efficient and Selective Visible‐Light Sensitive Photocatalyst

Nb-doped TiO2 coatings developed by high power impulse magnetron sputtering-chemical vapor deposition hybrid deposition process

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The Role of Nb Addition in TiO2 Nanoparticles: Phase Transition and Photocatalytic Properties

Cited by 8 publications

References 83 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

Silver Nanocluster Anchored TiO2/Nb2O5 Hybrid Nanocomposite as Highly Efficient and Selective Visible‐Light Sensitive Photocatalyst

Nb-doped TiO2 coatings developed by high power impulse magnetron sputtering-chemical vapor deposition hybrid deposition process

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The Role of Nb Addition in TiO₂ Nanoparticles: Phase Transition and Photocatalytic Properties

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

Silver Nanocluster Anchored TiO₂/Nb₂O₅ Hybrid Nanocomposite as Highly Efficient and Selective Visible‐Light Sensitive Photocatalyst