Titanium-Dioxide-Based Visible-Light-Sensitive Photocatalysis: Mechanistic Insight and Applications

Higashimoto, Shinya

doi:10.3390/catal9020201

Cited by 79 publications

(45 citation statements)

References 90 publications

(130 reference statements)

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“…The oxidizing and reducing nature of photo-generated holes and electrons, respectively, in TiO2 produce superoxide [1,2]. TiO2 nanoparticle films are used in photo semiconductor, photo-oxidation of water and photo-catalysis [3,4]. Photo semiconducting titanium dioxide thin films are important in processes where the transparency of the film required.…”

Section: Introductionmentioning

confidence: 99%

Effect of Concentration Variation on Optical and Structural Properties of TiO2 Thin Films

Ezike

2020

J. Mod. Mater.

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Concentrations in weight percent (5- 25 wt %) of TiO2 films used to optimize the film formation. The TiO2 films on glass substrates successfully obtained by spin-coating process using TiO2 nanopowder as precursor. Ultraviolet-Visible (UV-Vis), Scanning Electron Microscopy (SEM) equipped with Electron Diffraction X-ray (EDX) and X-ray Diffractometer (XRD) techniques used to characterize the films. The result of electron transport material (TiO2) showed that film prepared from 15 wt % of TiO2 solution and annealed at 450 has highest transmittance at visible light region with indirect optical band gap of 3.24 eV which corresponds to wavelength of 382 nm whereas 20 wt % has indirect band gap of 2.99 nm equivalent to 414.7 nm . The chemical analysis from Electron Diffraction Spectroscopy (EDS) of the material shows titanium and oxygen present at L and K-shells, respectively. The sample crystallized with preferred orientation at (101) from XRD analysis.

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Section: Introductionmentioning

confidence: 99%

Effect of Concentration Variation on Optical and Structural Properties of TiO2 Thin Films

Ezike

2020

J. Mod. Mater.

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“…5-6 times higher than that of 0/TiO 2 . This platinum-loading effect was attributable to the enhancement of electron transfer (reduction) of surface-adsorbed molecular oxygen (O 2 ), as has often been reported [17][18][19]. Since the conduction-band bottom of the anatase titania was sufficiently higher (more cathodic) than the standard electrode potential (SEP) of one-electron reduction of O 2 and the surface of anatase titania could induce electron transfer to surface-adsorbed O 2 , the enhancement ratio was not overly high when compared to the case of rutile titania or tungstena [20,21].…”

Section: Photocatalytic Activity Of Samplesmentioning

confidence: 59%

Correlation of the Photocatalytic Activities of Cu, Ce and/or Pt-Modified Titania Particles with their Bulk and Surface Structures Studied by Reversed Double-Beam Photoacoustic Spectroscopy

et al. 2019

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Modified titania photocatalyst powder samples were prepared using the sol-gel method for copper (Cu) and cerium (Ce) doping and impregnation for platinum (Pt) loading. Their bulk crystalline structures were investigated using X-ray diffractometry (XRD) with the Rietveld analysis. The surface/bulk structure, surface properties, and morphologies were observed using reversed double-beam photoacoustic spectroscopy (RDB-PAS), nitrogen adsorption, and scanning electron microscopy, respectively. The results from the XRD revealed that all samples were mainly anatase (ca. 80% or higher) with small amounts of rutile and non-crystalline components. The specific surface areas of all samples were in the range of 115-155 m 2 g −1 . Ce and Cu species were mainly distributed, while Pt was potentially loaded as a partially oxidized form on the titania surface. The results from the RDB-PAS indicated the changing of the energy-resolved distribution of electron traps (ERDT) from the original titania surface upon doping of the metals (Cu, Ce, and Pt), which altered their catalytic activities. The metals photocatalytic activities with UV irradiation were measured in two representative reactions; (a) CO 2 evolution from acetic acid under the aerobic condition and (b) H 2 evolution from deaerated aqueous methanol. In reaction (a), the Cu and/or Ce modification gave almost the same or slightly lower activity compared to the non-modified titania samples, while platinum loading yielded ca. 5-6 times higher activity. For reaction (b), the photocatalytic tests were divided into two sets; without (b 1 ) and with (b 2 ) Pt deposition during the reaction. Similar enhancements of activity from the Pt loading sample (and by Cu modification) were observed in reaction (b 1 ) without in-situ platinum deposition, while the unmodified and Ce-doped samples were almost inactive. For the activities of reaction (b 2 ) with in-situ platinum deposition, the unmodified samples showed the highest activity while the Cu-modified samples showed significantly lower activity. deposition under UV-light irradiation [1][2][3][4]. The basic principle for these photocatalytic reactions is that a photoexcited electron in a conduction band and a positive hole in a valence band, created by UV photoabsorption of titania photocatalysts, will reduce and oxidize, respectively, the surface-adsorbed substrates. The band-structure model (BSM) has been used, not limited to titania photocatalysis, for the explanation of reaction mechanisms, as well as the difference in photocatalytic activities. However, the photocatalytic reaction rates probably depend on the type and surface properties of the photocatalysts. The limitations of using the BSM to describe the relationship between photocatalyst properties and photocatalytic activities are that the BSM does not include information on the surface structure/property of photocatalyst particles and it does not include the description on the surface structure, where electrons and positive holes are transferred to the surface-adsorbed subs...

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“…However, this method has the disadvantage of overestimating the size in the small size region. Hence, we have used the new empirical formula suggested by Ranjani Viswanatha et al [12], (1) where Eg is the shift in the energy band gap and d is the diameter of the particle. The particle size of CdS thus calculated was 2 nm (Table 1).…”

Section: Experimental Methodsmentioning

confidence: 99%

“…The band gap of TiO2 is generally a range of 3.0-3.2 eV which means that UV light irradiation with a wavelength lower than 400 nm only initiate photo-reaction. Many composites have been tried to improve the efficiency of pure TiO2 by improving the absorption in the visible region of the solar spectrum as well [1,2]. This can be done either by Surface modifications achieved by anchoring colored inorganic semiconductors (for example, CdS and CdSe) or organic dyes on the TiO2 surface, where they act as sensitizers [3,4].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Photocatalytic Studies of TiO2-CdS Nanocomposite

Krishnan¹,

Menon²

2019

JNST

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Considering the importance of photo catalytic oxidation of organic pollutants by semiconductors using sunlight, in the present study, we prepared and studied CdS-TiO2 nanocomposite. The commonly used photocatalyst TiO2 as such has the drawback that it uses only the UV portion of sunlight. The CdS-TiO2 composite was prepared by a modified sol-gel method. The structure and optical properties were studied by means of XRD, TEM and UV-visible spectroscopy. The composite was tested for their photocatalytic efficiency by the time taken for the degradation of the dye methyl orange under illumination of by absorption spectroscopy of samples extracted at different time intervals. It is found that CdS-TiO2 is more efficient as a photocatalyst than pure TiO2.This is due to better absorption of light in the visible range.

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Titanium-Dioxide-Based Visible-Light-Sensitive Photocatalysis: Mechanistic Insight and Applications

Cited by 79 publications

References 90 publications

Effect of Concentration Variation on Optical and Structural Properties of TiO2 Thin Films

Effect of Concentration Variation on Optical and Structural Properties of TiO2 Thin Films

Correlation of the Photocatalytic Activities of Cu, Ce and/or Pt-Modified Titania Particles with their Bulk and Surface Structures Studied by Reversed Double-Beam Photoacoustic Spectroscopy

Synthesis and Photocatalytic Studies of TiO2-CdS Nanocomposite

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