Effect of Au clustering on ferromagnetism in Au doped TiO2 films: theory and experiments investigation

Zou, Zhaorui; Zhou, Zhongpo; Wang, Haiying; Yang, Zongxian

doi:10.1016/j.jpcs.2016.09.011

Cited by 13 publications

(7 citation statements)

References 32 publications

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“…The 2.5 wt%Pt-TiO 2 had showed the optimum catalytic performance and a reduction in the TiO 2 band gap energy from 3.00 to 2.34 eV with an enhanced electron storage capacity, leading to a minimization of the electron-hole recombination rate [34]. Noble metal nanoparticles such as Ag [35], Pt [34], Pd [36], Rh [37] and Au [38] have also been used to modify TiO 2 for photocatalysis and have been reported to efficiently hinder electron-hole recombination due to the resulting Schottky barrier at the metal-TiO 2 interface. The noble metal nanoparticles act as a mediator in storing and transporting photogenerated electrons from the surface of TiO 2 to an acceptor.…”

Section: Metal Dopingmentioning

confidence: 99%

Modified Titanium Dioxide for Photocatalytic Applications

Moma¹,

Baloyi²

2019

Photocatalysts - Applications and Attributes

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Titanium dioxide (TiO 2) has been widely used as a photocatalyst in many environmental and energy applications due to its efficient photoactivity, high stability, low cost, and safety to the environment and humans. However, its large band gap energy, ca. 3.2 eV limits its absorption of solar radiation to the UV light range which accounts for only about 5% of the solar spectrum. Furthermore, the photocatalytic activity of TiO 2 is also limited by the rapid recombination of the photogenerated electron-hole pairs. When used in water treatment applications, TiO 2 has a poor affinity toward organic pollutants, especially hydrophobic organic pollutants. Several strategies have been employed to reduce its band gap energy, its electron-hole recombination rates as well as enhance its absorption of organic pollutants. In this chapter, we review some of the most recent works that have employed the doping, decoration, and structural modification of TiO 2 particles for applications in photocatalysis. Additionally, we discuss the effectiveness of these dopants and/or modifiers in enhancing TiO 2 photoactivity as well as some perspective on the future of TiO 2 photocatalysis.

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Section: Metal Dopingmentioning

confidence: 99%

Modified Titanium Dioxide for Photocatalytic Applications

Moma¹,

Baloyi²

2019

Photocatalysts - Applications and Attributes

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“…Other studies show, instead, that if TiO 2 is modified by adding noble metals (such as Ag, Pt, Pd, Rh and Au), electron-hole recombination is hindered by the resulting Schottky barrier at the metal–TiO 2 interface, where the former acts as a storing-transporting mediator of photogenerated electrons from the surface of TiO 2 to an acceptor (in the reaction medium). Consequently, the photocatalytic activity increases as the charge carrier recombination rate decreases [22,23,24,25,26].…”

Section: Introductionmentioning

confidence: 99%

Application of Reverse Micelle Sol–Gel Synthesis for Bulk Doping and Heteroatoms Surface Enrichment in Mo-Doped TiO2 Nanoparticles

et al. 2019

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TiO2 nanoparticles containing 0.0, 1.0, 5.0, and 10.0 wt.% Mo were prepared by a reverse micelle template assisted sol–gel method allowing the dispersion of Mo atoms in the TiO2 matrix. Their textural and surface properties were characterized by means of X-ray powder diffraction, micro-Raman spectroscopy, N2 adsorption/desorption isotherms at −196 °C, energy dispersive X-ray analysis coupled to field emission scanning electron microscopy, X-ray photoelectron spectroscopy, diffuse reflectance UV–Vis spectroscopy, and ζ-potential measurement. The photocatalytic degradation of Rhodamine B (under visible light and low irradiance) in water was used as a test reaction as well. The ensemble of the obtained experimental results was analyzed in order to discover the actual state of Mo in the final materials, showing the occurrence of both bulk doping and Mo surface species, with progressive segregation of MoOx species occurring only at a higher Mo content.

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“…However, the presence of Cr 3+ ions at the interstitial site in doped samples may be responsible for a decrease in the magnetic moment for the samples containing 10%, 15% and 20% Cr ions. The other reason could be the nonappearance of the formation of oxygen vacancies that can be attributed to superexchange interaction between Cr 3+ −Cr 3+ or Cr 3+ −O−Cr 3+ related to the alignment of the antiparallel spins 3,51 . The inset of Figure 12 demonstrates the presence of the short‐range order of ferromagnetic interactions in both prepared pristine and Cr‐doped samples by showing a modest opening of all hysteresis loops with nonzero values of M r and H c .…”

Section: Resultsmentioning

confidence: 95%

“…The other reason could be the nonappearance of the formation of oxygen vacancies that can be attributed to superexchange interaction between Cr 3+ −Cr 3+ or Cr 3+ −O−Cr 3+ related to the alignment of the antiparallel spins. 3,51 The inset of Figure 12 demonstrates the presence of the short-range order of ferromagnetic interactions in both prepared pristine and Cr-doped samples by showing a modest opening of all hysteresis loops with nonzero values of M r and H c . Table 4 lists the magnetic parameters that have been experimentally evaluated, including M s , M r and H c .…”

Section: Magnetic Propertiesmentioning

confidence: 93%

Physical properties and photocatalytic activity of Cr‐doped TiO₂ nanoparticles

Abushad

Naseem

Arshad

et al. 2023

Journal of Microscopy

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Nanocrystalline Ti1‐xCrxO2 (0 ≤ x ≤ 0.20) samples were synthesised via acid‐modified sol‐gel process and characterised with various techniques, such as HRTEM, FESEM, Raman, XPS, DTA and VSM. The TEM image of TiO2 exhibits elongated nanoparticles with an average size of 10 nm. The HRTEM in combination with selected area electron diffraction (SAED) reveals the interplanar spacing and polycrystalline nature of the samples, respectively. FESEM micrographs divulge nonuniform morphologies and less aggregation of the particles in the doped sample. Raman spectra ensure the phase purity of the samples and a blue shift on Cr doping. X‐ray photoelectron spectra (XPS) predict the chemical state of the elements and oxygen vacancies in the prepared samples. Room temperature magnetic measurements exhibit a significant variation in the magnetic parameters on Cr doping in TiO2. The differential thermal analysis (DTA) shows the structural phase transition at ∼630°C. The photocatalytic performance is studied for the degradation of methylene blue (MB) dye under visible light irradiation. A higher photocatalytic efficiency is found for the 20% of Cr‐doped TiO2. These studies propose that the appropriate incorporation of Cr ions makes TiO2 very efficient for visible light‐driven photocatalysts required for applications in wastewater treatment.LAY DESCRIPTION: In the present study, nanoparticles of TiO2 and Cr‐doped TiO2 have been synthesised by a cost‐effective acid‐modified sol‐gel process. The effect of Cr doping on the microstructure, thermal, magnetic and photocatalytic properties of TiO2 were explored in detail. The transmission electron microscopy (TEM) images exhibit the presence of elongated nanoparticles with an average size of 10 nm. Field emission scanning electron microscopy (FESEM) was used to study the surface morphology of the synthesised materials, which revealed nonuniform morphologies and less aggregation of the particles in the Cr‐doped sample. Energy dispersive x‐ray spectroscopy (EDS) confirms the elemental compositions with the appropriate stoichiometry of the elements. Raman spectra ensure the phase purity of the materials and also a blue shift with the incorporation of Cr ions in TiO2. X‐ray photoelectron spectra (XPS) predict the chemical state of the elements and oxygen vacancies in the prepared samples. The magnetic nature of all the synthesised samples was examined through the vibrating sample magnetometer (VSM) and revealed weak ferromagnetic behaviour of the samples. These results signify that the oxygen vacancies and defects play a crucial role in developing the ferromagnetic nature of oxide semiconductors. The differential thermal analysis (DTA) shows the structural phase transition at ∼630°C. The photocatalytic performance of the prepared samples was studied for the degradation of methylene blue (MB) dye under irradiation of visible light. A higher photocatalytic efficiency was found for the 20% of Cr‐doped TiO2. These studies propose that the appropriate incorporation of Cr ions makes TiO2 very efficient for visible light‐driven photocatalysts required for applications in wastewater treatment.

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Effect of Au clustering on ferromagnetism in Au doped TiO2 films: theory and experiments investigation

Cited by 13 publications

References 32 publications

Modified Titanium Dioxide for Photocatalytic Applications

Modified Titanium Dioxide for Photocatalytic Applications

Application of Reverse Micelle Sol–Gel Synthesis for Bulk Doping and Heteroatoms Surface Enrichment in Mo-Doped TiO2 Nanoparticles

Physical properties and photocatalytic activity of Cr‐doped TiO₂ nanoparticles

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Effect of Au clustering on ferromagnetism in Au doped TiO2 films: theory and experiments investigation

Cited by 13 publications

References 32 publications

Modified Titanium Dioxide for Photocatalytic Applications

Modified Titanium Dioxide for Photocatalytic Applications

Application of Reverse Micelle Sol–Gel Synthesis for Bulk Doping and Heteroatoms Surface Enrichment in Mo-Doped TiO2 Nanoparticles

Physical properties and photocatalytic activity of Cr‐doped TiO2 nanoparticles

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Physical properties and photocatalytic activity of Cr‐doped TiO₂ nanoparticles