Atomic Layer Deposition Al2O3 Coatings Significantly Improve Thermal, Chemical, and Mechanical Stability of Anodic TiO2 Nanotube Layers

Zazpe, Raúl; Přikryl, Jan; Gärtnerová, V.; Nechvílová, Kateřina; Beneš, Ludvı́k; Strizik, Lukas; Jäger, Aleš; Bosund, Markus; Sopha, Hanna; Macák, Jan M.

doi:10.1021/acs.langmuir.7b00187

Cited by 47 publications

(29 citation statements)

References 62 publications

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“…In order to provide an additional proof of MoSe x O y successful coatings, the energy‐dispersive X‐ray spectroscopy (EDX) elemental mapping and line scan of the 50 cycles MoSe x O y ‐coated TiO 2 nanotube layer taken from the interface of the bottom part of the TiO 2 nanotube layer and the underlying Ti substrate is shown in Figures S1 and S2 (Supporting Information). Similar uniform and ultrathin coatings within TiO 2 nanotube layers were also observed in our previous works for various secondary materials, including Al 2 O 3 , TiO 2 , ZnO, and CdS . By measuring the thickness of the MoSe x O y shown in Figure a,b, we estimate that the thickness of the 50 cycles MoSe x O y coating is ≈10 nm.…”

Section: Resultssupporting

confidence: 87%

MoSe_xO_y‐Coated 1D TiO₂ Nanotube Layers: Efficient Interface for Light‐Driven Applications

Krbal

Zazpe

et al. 2017

Adv Materials Inter

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in the materials science community. [2] Apart from the generation of H 2 and O 2 gases, photocatalysis can be extended to other applications. The early works on the irradiation of TiO 2 for purification of water via photocatalytic decomposition of pollutants were demonstrated by Frank and Bard in late 1970s. [3][4][5] These initial works and many reports later have shown that photooxidation of inorganic and organic contaminants is a promising route for environmental remediation. [6][7][8][9][10][11][12] In fact, the key factors that determine the efficiencies of a photocatalyst include its light harvesting capability and reduced charge carriers recombination of the photo generated electron-hole pairs. [3,13] However, TiO 2 possesses rather wide bandgap energies between 3.0 and 3.2 eV, with high photo activity only in the UV region (λ ≤ 390 nm) equivalent to only ≈5% of the solar spectrum. [14,15] Nevertheless, owing to its nontoxicity, low-cost synthesis, chemical inertness, and resistance against photocorrosion, TiO 2 has been long studied and recognized as the most promising photocatalyst material. [13,16] In order to harness more from the abundant renewable energy source, that is, solar energy, tremendous efforts have been devoted to reduce the bandgap energy of TiO 2 and broaden its optical absorption to the visible region. [8,[13][14][15]17,18] Bandgap engineering has been extensively carried out Ultrathin molybdenum oxyselenide (MoSe x O y ) coatings are made first ever by atomic layer deposition (ALD) within anodic 1D TiO 2 nanotube layers for photoelectrochemical and photocatalytic applications. The coating thickness is controlled through varying ALD cycles from 5 to 50 cycles (corresponding to ≈1-10 nm). In the ultraviolet region, the coatings have enhanced up to four times the incident photon-to-current conversion efficiency (IPCE), and the highest IPCE is recorded at 32% at (at λ = 365 nm). The coatings notably extend the photoresponse to the visible spectral region and remarkable improvement of photocurrent densities up to ≈40 times is registered at λ = 470 nm. As a result, the MoSe x O y -coated-TiO 2 nanotube layers have shown to be an effective photocatalyst for methylene blue degradation, and the optimal performance is credited to a coating thickness between 2 and 5 nm (feasible only by ALD). The enhancement in photoactivities of the presented heterojunction is mainly associated with the passivation effect of MoSe x O y on the TiO 2 nanotube walls and the suitability of bandgap position between MoSe x O y and TiO 2 interface for an efficient charge transfer. In addition, MoSe x O y possesses a narrow bandgap, which favors the photoactivity in the visible spectral region.

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Section: Resultssupporting

confidence: 87%

MoSe_xO_y‐Coated 1D TiO₂ Nanotube Layers: Efficient Interface for Light‐Driven Applications

Krbal

Zazpe

et al. 2017

Adv Materials Inter

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“…Both images show two distinct tube walls, and the white ZnO layer completely enfolds the tubes. Similarly, homogeneous coatings were achieved within our previous works on Al 2 O 3 coatings for thermal stability and Li‐ion batteries, TiO 2 coatings for photocatalysis, and CdS coatings for solar cells, respectively, within anodic TiO 2 nanotube layers. Figure e and f show the selected area electron diffraction (SAED) and XRD patterns of the ZnO (19 nm) coatings within TiO 2 nanotube layers, respectively.…”

Section: Resultsmentioning

confidence: 70%

“…The peculiar characteristics are particularly helpful for the deposition of a secondary material in high aspect ratio structures, such as porous anodic alumina, and TiO 2 nanotube layers, as in this study. Very recently, a few works have shown the potential of ALD secondary material in TiO 2 nanostructures . These include ALD ZnO loaded TiO 2 nanowires and nanotubes, both focused on the photocatalytic and photoelectrochemcial (PEC) applications .…”

Section: Introductionmentioning

confidence: 99%

ZnO Coated Anodic 1D TiO₂ Nanotube Layers: Efficient Photo‐Electrochemical and Gas Sensing Heterojunction

Kuberský

Krbal

et al. 2017

Adv Eng Mater

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The authors demonstrate, in this work, a fascinating synergism of a high surface area heterojunction between TiO 2 in the form of ordered 1D anodic nanotube layers of a high aspect ratio and ZnO coatings of different thicknesses, produced by atomic layer deposition. The ZnO coatings effectively passivate the defects within the TiO 2 nanotube walls and significantly improve their charge carrier separation. Upon the ultraviolet and visible light irradiation, with an increase of the ZnO coating thickness from 0.19 to 19 nm and an increase of the external potential from 0.4-2 V, yields up to 8-fold enhancement of the photocurrent density. This enhancement translates into extremely high incident photon to current conversion efficiency of %95%, which is among the highest values reported in the literature for TiO 2 based nanostructures. In addition, the photoactive region is expanded to a broader range close to the visible spectral region, compared to the uncoated nanotube layers. Synergistic effect arising from ZnO coated TiO 2 nanotube layers also yields an improved ethanol sensing response, almost 11-fold compared to the uncoated nanotube layers. The design of the high-area 1D heterojunction, presented here, opens pathways for the light-and gas-assisted applications in photocatalysis, water splitting, sensors, and so on.

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“…Titania in the rutile phase is more mechanically robust than anatase, as its octahedra shares four edges instead of four corners in the anatase octahedra [97]. Hence, there is increasing interest in annealing the amorphous TNTs in order to enhance the elastic modulus, hardness and adhesive strength [89][90][91][92][93].…”

Section: Physical Treatmentmentioning

confidence: 99%

“…In addition, the deposition of an appropriate secondary material on the fabricated The heat treated Al2O3-coated TNTs exhibited higher hardness with increasing coating thickness, which was attributed to more Al2O3 mass within the TNTs and increased content of rutile titania [97]. Undoubtedly, some of these modifications may alter the surface chemistry of the nano-engineered implant and thereby can influence cellular interactions, which is an issue that requires further exploration.…”

Section: Physical Treatmentmentioning

confidence: 99%

Understanding and augmenting the stability of therapeutic nanotubes on anodized titanium implants

Gulati

Wang

et al. 2018

Materials Science and Engineering: C

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Titanium is an ideal material choice for orthopaedic and dental implants, and hence a significant amount of research has been focused towards augmenting the therapeutic efficacy of titanium surfaces. More recently the focus has shifted to nano-engineered implants fabricated via anodization to generate self-ordered nanotubular structures composed of titania (TiO). These structures (titania nanotubes/TNTs) enable local drug delivery and tailorable cellular modulation towards achieving desirable effects like enhanced osseointegration and antibacterial action. However, the mechanical stability of such modifications is often ignored and remains underexplored, and any delamination or breakage in the TNTs modification can initiate toxicity and lead to severe immuno-inflammatory reactions. This review details and critically evaluates the progress made in relation to this aspect of TNT based implants, with a focus on understanding the interface between TNTs and the implant surface, treatments aimed at augmenting mechanical stability and strategies for advanced mechanical testing within the bone micro-environment ex vivo and in vivo. This review article extends the existing knowledge in this domain of TNTs implant technology and will enable improved understanding of the underlying parameters that contribute towards mechanically robust nano-engineered implants that can withstand the forces associated with implant surgical placement and the load bearing experienced at the bone/implant interface.

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Atomic Layer Deposition Al₂O₃ Coatings Significantly Improve Thermal, Chemical, and Mechanical Stability of Anodic TiO₂ Nanotube Layers

Cited by 47 publications

References 62 publications

MoSe_xO_y‐Coated 1D TiO₂ Nanotube Layers: Efficient Interface for Light‐Driven Applications

MoSe_xO_y‐Coated 1D TiO₂ Nanotube Layers: Efficient Interface for Light‐Driven Applications

ZnO Coated Anodic 1D TiO₂ Nanotube Layers: Efficient Photo‐Electrochemical and Gas Sensing Heterojunction

Understanding and augmenting the stability of therapeutic nanotubes on anodized titanium implants

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Atomic Layer Deposition Al2O3 Coatings Significantly Improve Thermal, Chemical, and Mechanical Stability of Anodic TiO2 Nanotube Layers

Cited by 47 publications

References 62 publications

MoSexOy‐Coated 1D TiO2 Nanotube Layers: Efficient Interface for Light‐Driven Applications

MoSexOy‐Coated 1D TiO2 Nanotube Layers: Efficient Interface for Light‐Driven Applications

ZnO Coated Anodic 1D TiO2 Nanotube Layers: Efficient Photo‐Electrochemical and Gas Sensing Heterojunction

Understanding and augmenting the stability of therapeutic nanotubes on anodized titanium implants

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Product

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Atomic Layer Deposition Al₂O₃ Coatings Significantly Improve Thermal, Chemical, and Mechanical Stability of Anodic TiO₂ Nanotube Layers

MoSe_xO_y‐Coated 1D TiO₂ Nanotube Layers: Efficient Interface for Light‐Driven Applications

MoSe_xO_y‐Coated 1D TiO₂ Nanotube Layers: Efficient Interface for Light‐Driven Applications

ZnO Coated Anodic 1D TiO₂ Nanotube Layers: Efficient Photo‐Electrochemical and Gas Sensing Heterojunction