Amorphous TiO<sub>2</sub>nanostructures: synthesis, fundamental properties and photocatalytic applications

Sun, Shaodong; Song, Peng; Cui, Jie; Liang, Shuhua

doi:10.1039/c9cy01020c

Cited by 118 publications

(75 citation statements)

References 164 publications

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“…The carrier lifetime and recombination processes depend critically on the crystal structure of TiO 2 . The long range disorder of amorphous TiO 2 (am.-TiO 2 ) results in under and over-coordinated Ti ions in which short staggered chains of edge and vertex linked Ti–O octahedral like units are present [ 16 ]. Prasai et al [ 17 ] have proposed that long-range disorder affects the localization of band edge states.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Photogenerated Charge Carrier Lifetimes in ALD Grown TiO2 for Photonic Applications

et al. 2020

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Titanium dioxide (TiO2) thin films are widely employed for photocatalytic and photovoltaic applications where the long lifetime of charge carriers is a paramount requirement for the device efficiency. To ensure the long lifetime, a high temperature treatment is used which restricts the applicability of TiO2 in devices incorporating organic or polymer components. In this study, we exploited low temperature (100–150 °C) atomic layer deposition (ALD) of 30 nm TiO2 thin films from tetrakis(dimethylamido)titanium. The deposition was followed by a heat treatment in air to find the minimum temperature requirements for the film fabrication without compromising the carrier lifetime. Femto-to nanosecond transient absorption spectroscopy was used to determine the lifetimes, and grazing incidence X-ray diffraction was employed for structural analysis. The optimal result was obtained for the TiO2 thin films grown at 150 °C and heat-treated at as low as 300 °C. The deposited thin films were amorphous and crystallized into anatase phase upon heat treatment at 300–500 °C. The average carrier lifetime for amorphous TiO2 is few picoseconds but increases to >400 ps upon crystallization at 500 °C. The samples deposited at 100 °C were also crystallized as anatase but the carrier lifetime was <100 ps.

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Section: Introductionmentioning

confidence: 99%

Optimization of Photogenerated Charge Carrier Lifetimes in ALD Grown TiO2 for Photonic Applications

et al. 2020

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“…The performance of these as well as other systems used in photocatalysis and photoelectrocatalysis [11] is affected or governed by electrons and/or holes induced by dopants (such as H, Li, Nb, and vacancy defects) [12][13][14][15][16][17], photoexcitation, and as a result of carrier injection from electrodes. In similar wide-gap semiconductors, excess charges often localize at regular lattice sites or impurities and modify the electronic structure by creating the corresponding shallow or deep gap states [18].…”

Section: Introductionmentioning

confidence: 99%

Disorder-induced electron and hole trapping in amorphous TiO2

2020

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Thin films of amorphous (a)-TiO 2 are ubiquitous as photocatalysts, protective coatings, photo-anodes, and in memory applications, where they are exposed to excess electrons and holes. We investigate trapping of excess electrons and holes in the bulk of pure amorphous titanium dioxide, a-TiO 2 , using hybrid density-functional theory (h-DFT) calculations. Fifty 270-atom a-TiO 2 structures were produced using classical molecular dynamics and their geometries fully optimized using h-DFT simulations. They have the density, distribution of atomic coordination numbers, and radial pair-distribution functions in agreement with experiments. The calculated average a-TiO 2 band gap is 3.25 eV with no states splitting into the band gap. Trapping of excess electrons and holes in a-TiO 2 is predicted at precursor sites, such as elongated Ti-O bonds. Single electron and hole polarons have average trapping energies (E T) of −0.4 eV and −0.8 eV, respectively. We also identify several types of electron and hole bipolaron states and discuss their stability. These results can be used for understanding the mechanisms of photo-catalysis and improving the performance of electronic devices employing a-TiO 2 films.

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“…DSSC consists of a mesoporous (Titania) TiO 2 layer adsorbing a monolayer of dye molecules, an electrolyte based redox system for charge transport, and counter electrodes to collect photogenerated carriers [3], which has high power-conversion efficiency [4]. To optimise the performance of DSSCs, research universities and institutes are now working on TiO 2 photoanodes fabrication with different forms of nanostructure morphologies [5][6][7]. Because of their advantages, which include abundantly available inexpensive materials and potentially lower costs of fabrication, DSSCs offer a promising alternative to thin-film silicon solar cells [8].…”

Section: Introductionmentioning

confidence: 99%

A simulation study on the effect of size gold nanoparticles on broadband light absorption in dye-sensitised solar cells

Qadir

2021

Rev. Mex. Fís.

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Plasmon-assisted energy conversion in dye-sensitised solar cells (DSSCs) has been achieved by applying gold (Au) nanoparticles (NPs) inside Titania (TiO2) photoanodes. Gold nanoparticles (GNPs) were introduced into DSSCs to further enhance their power conversion efficiency (PCE). In this research work, an effort has been made to enhance the optical absorption and improve the performance of DSSCs. By utilising finite-difference time-domain (FDTD) software, GNPs with radii of 15, 25, 35, 45, 55, 65, 75 and 85 nm were produced and introduced into the TiO2 photoanode. The optimum radius for the optical absorption enhancement was found to be 85 nm because the effect of plasmon coupling is more significant for metal nanoparticle sizes > 60 nm. The effect of various sizes of GNPs on light scattering has also been presented in this study. Moreover, the investigation has focused on the role of incident angle of light source on the absorption in TiO2 films. It was found that the optimum incident angle for the enhancement of broadband optical absorption in the wavelength range of 450–800 nm is 70°.

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Amorphous TiO₂nanostructures: synthesis, fundamental properties and photocatalytic applications

Abstract: In this review, we mainly highlight the advances made in the development of amorphous TiO2 nanostructures for photocatalysts. Some perspectives on the challenges and new direction are also discussed.

Cited by 118 publications

References 164 publications

Optimization of Photogenerated Charge Carrier Lifetimes in ALD Grown TiO2 for Photonic Applications

Optimization of Photogenerated Charge Carrier Lifetimes in ALD Grown TiO2 for Photonic Applications

Disorder-induced electron and hole trapping in amorphous TiO2

A simulation study on the effect of size gold nanoparticles on broadband light absorption in dye-sensitised solar cells

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Amorphous TiO2nanostructures: synthesis, fundamental properties and photocatalytic applications

Abstract: In this review, we mainly highlight the advances made in the development of amorphous TiO2 nanostructures for photocatalysts. Some perspectives on the challenges and new direction are also discussed.

Cited by 118 publications

References 164 publications

Optimization of Photogenerated Charge Carrier Lifetimes in ALD Grown TiO2 for Photonic Applications

Optimization of Photogenerated Charge Carrier Lifetimes in ALD Grown TiO2 for Photonic Applications

Disorder-induced electron and hole trapping in amorphous TiO2

A simulation study on the effect of size gold nanoparticles on broadband light absorption in dye-sensitised solar cells

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Product

Resources

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Amorphous TiO₂nanostructures: synthesis, fundamental properties and photocatalytic applications