Laser induced phase transformation influenced by Co doping in TiO2 nanoparticles

Gaur, Lalit Kumar; Kumar, Promod; Kushavah, Dushyant; Khiangte, Krista R.; Mathpal, Mohan Chandra; Agrahari, Vivek; Gairola, S.P.; Soler, Maria A. G.; Swart, H.C.; Agarwal, Arvind

doi:10.1016/j.jallcom.2018.11.344

Cited by 40 publications

(12 citation statements)

References 38 publications

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“…In accordance with the XRD results, we think that this band shift was due to the formation of Fe-O and Co-O bonds, which occurred following the substitution of Ti 4+ with Fe 3+ and Co 3+ within the TiO 2 lattice. This sort of frequency shifting was also presented by other researchers [32,38,43].…”

Section: Resultssupporting

confidence: 81%

“…Based on this, and the results of a previous X-ray photoelectron spectroscopy (XPS) study that revealed the coexistence of Co 2+ and Co 3+ on the surface of Co-doped TiO 2 NPs [25], and by comparing the cationic radius values of Co 2+ (0.74 Å), Co 3+ (0.61 Å), Fe 2+ (0.76 Å), and Fe 3+ (0.65 Å) to that of Ti 4+ (0.68 Å) [25,28,30,31,32], we hypothesize that some of the doping elements were incorporated into the structures of Titania and replaced the titanium ions, which induced a perturbation in anatase crystal structure; as a result, the crystallinity decreased and the peak position shifted. A similar behavior was reported in the literature [15,28,32,33]. The average crystallite size of the samples was estimated from the Full width at half maximum (FWHM) of the prominent peak (101) of anatase, using the Debye-Scherer method [34,35].…”

Section: Resultsmentioning

confidence: 99%

“…The low-frequency broad band located in the range 400–900 cm −1 corresponded to the Ti-O-Ti vibrational mode [39,42]. Interestingly, a shift of this band position to a lower wave number was observed for both Fe- and Co-doped TiO 2 NPs, indicating the existence of structure defects [32,43]. In accordance with the XRD results, we think that this band shift was due to the formation of Fe-O and Co-O bonds, which occurred following the substitution of Ti 4+ with Fe 3+ and Co 3+ within the TiO 2 lattice.…”

Section: Resultsmentioning

confidence: 99%

“…Raman spectroscopy is one of the most efficient analysis techniques to investigate the structural properties of materials. The changes in Raman spectra are related to non-stoichiometry, structure defects, phase changes, and bond modifications [18,32,40,44,45]. Figure 3 shows the Raman spectra of pure TiO 2 , Co-doped TiO 2 , and Fe-doped TiO 2 .…”

Section: Resultsmentioning

confidence: 99%

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Synthesis of Fe- and Co-Doped TiO2 with Improved Photocatalytic Activity Under Visible Irradiation Toward Carbamazepine Degradation

et al. 2019

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Pure TiO2 and Fe- and Co-doped TiO2 nanoparticles (NPs) as photocatalysts were synthesized using wet chemical methods (sol-gel + precipitation). Their crystalline structure and optical properties were analyzed using X-ray diffraction (XRD), Raman spectroscopy and Fourier-transform infrared (FTIR) spectroscopy, ultraviolet-visible light (UV-Vis) diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. The photocatalytic activity of the synthesized nanoparticles was evaluated through degradation of carbamazepine (CBZ) under UV-A and visible-light irradiations. The XRD and Raman analyses revealed that all synthesized nanomaterials showed only the anatase phase. The DRS results showed that the absorption edge was blue-shifted for Fe-doped TiO2 NPs. The decrease in charge recombination was evidenced from the PL investigation for both Co-doped and Fe-doped TiO2 nanomaterials. An enhancement in photocatalytic degradation of carbamazepine in aqueous suspension under both UV-A light and visible-light irradiations was observed for Fe-doped Titania NPs by comparison with pure TiO2. These results suggest that the doping cations could suppress the electron/hole recombination. Therefore, the photocatalytic activity of TiO2-based nanomaterials was enhanced.

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Section: Resultssupporting

confidence: 81%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Synthesis of Fe- and Co-Doped TiO2 with Improved Photocatalytic Activity Under Visible Irradiation Toward Carbamazepine Degradation

et al. 2019

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“…TiO 2 anatase phase is easily prepared at a calcination temperature around 500°C, owing to its low surface free energy [13,20]. The phase transformation of TiO 2 mostly relies on surface defects (oxygen vacancies, Ti interstitials), crystal strain, particle size, existence of additives or dopants, and calcination conditions [20][21][22]. 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].…”

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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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Density Functional Theory Study of ZnIn₂S₄ and CdIn₂S₄ Polymorphs Using Full‐Potential Linearized Augmented Plane Wave Method and Modified Becke–Johnson Potential

Zhang

Tang

Gao

2019

Physica Status Solidi (b)

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ZnIn2S4 and CdIn2S4 are ternary sulfide semiconductors with attracting photoelectric and catalytic properties, which are closely related with their band structure. The full‐potential linearized augmented plane wave (FP‐LAPW) method is used to calculate the band structures of cubic and hexagonal polymorphs of ZnIn2S4 and CdIn2S4. Among the four systems studied, the hexagonal CdIn2S4 structure with a space group P63mc (No. 186) is newly predicted, and the phonon calculation shows that its structure is dynamically stable. Owing to the well‐known bandgap underestimation problem of local density approximation (LDA) and generalized gradient approximation (GGA), the effects of Hubbard model and modified Becke–Johnson (mBJ) potential to band structure are investigated. The calculated outcomes of cubic ZnIn2S4 and cubic CdIn2S4 with mBJ‐GGA + U are in good agreement with the experimental data. For hexagonal ZnIn2S4, it is shown that electronic states in high valence bands and low conduction bands have different components. The origin of discrepancy between the theoretical bandgap of hexagonal ZnIn2S4 and experimental value obtained from optical absorption measurement is discussed based on the spatial separation of electron and hole states and optical transition probability.

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Laser induced phase transformation influenced by Co doping in TiO2 nanoparticles

Cited by 40 publications

References 38 publications

Synthesis of Fe- and Co-Doped TiO2 with Improved Photocatalytic Activity Under Visible Irradiation Toward Carbamazepine Degradation

Synthesis of Fe- and Co-Doped TiO2 with Improved Photocatalytic Activity Under Visible Irradiation Toward Carbamazepine Degradation

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

Density Functional Theory Study of ZnIn₂S₄ and CdIn₂S₄ Polymorphs Using Full‐Potential Linearized Augmented Plane Wave Method and Modified Becke–Johnson Potential

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Laser induced phase transformation influenced by Co doping in TiO2 nanoparticles

Cited by 40 publications

References 38 publications

Synthesis of Fe- and Co-Doped TiO2 with Improved Photocatalytic Activity Under Visible Irradiation Toward Carbamazepine Degradation

Synthesis of Fe- and Co-Doped TiO2 with Improved Photocatalytic Activity Under Visible Irradiation Toward Carbamazepine Degradation

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

Density Functional Theory Study of ZnIn2S4 and CdIn2S4 Polymorphs Using Full‐Potential Linearized Augmented Plane Wave Method and Modified Becke–Johnson Potential

Contact Info

Product

Resources

About

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

Density Functional Theory Study of ZnIn₂S₄ and CdIn₂S₄ Polymorphs Using Full‐Potential Linearized Augmented Plane Wave Method and Modified Becke–Johnson Potential