Composition and properties of RF-sputter deposited titanium dioxide thin films

Daughtry, Jesse; Alotabi, Abdulrahman S.; Howard-Fabretto, Liam; Andersson, Gunther G.

doi:10.1039/d0na00861c

Cited by 22 publications

(23 citation statements)

References 41 publications

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“…However, Cr 2 O 3 remains on top of the rutile phase because it has a higher surface energy than Cr 2 O 3 . In the case of the mixed anatase:rutile phases, the sample contains separate domains of anatase and rutile as evident from the AFM and SEM images elsewhere . Therefore, it is likely that Cr 2 O 3 has diffused into anatase but not into rutile.…”

Section: Resultsmentioning

confidence: 98%

“…In the case of the mixed anatase:rutile phases, the sample contains separate domains of anatase and rutile as evident from the AFM and SEM images elsewhere. 51 Therefore, it is likely that Cr 2 O 3 has diffused into anatase but not into rutile. It should be noted that diffusion of Cr 2 O 3 into the metal oxide substrate driven by surface energy is not significantly affected whether the sample is exposed to air or vacuum.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Investigation of the Diffusion of Cr₂O₃ into Different Phases of TiO₂ upon Annealing

Alotabi

Gibson

Metha

et al. 2021

ACS Appl. Energy Mater.

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Chromium oxide (Cr 2 O 3 ) can be used as a protective layer for photocatalysts to improve photocatalytic water splitting activity and is commonly photodeposited. However, it is not known how the conditions of the Cr 2 O 3 formation affect the formation of the protective layer and potential diffusion into the substrate onto which Cr 2 O 3 has been deposited. We have investigated the stability of Cr 2 O 3 photodeposited onto the surface of different crystal phases of TiO 2 with subsequent annealing at a range of temperatures up to 600 °C. X-ray photoelectron spectroscopy and synchrotron near-edge X-ray absorption fine structure were used to analyze the chemical composition of the sample, neutral impact collision ion scattering spectroscopy was used to study the concentration depth profile of the elements in the sample, and atomic force microscopy was used to investigate the morphology of the surface. Under annealing conditions, the Cr 2 O 3 layer diffuses into the amorphous and anatase phases of TiO 2 but remains at the surface of the rutile phase. This finding is attributed to differences in surface energy with Cr 2 O 3 being higher in surface energy than the amorphous and anatase phases of TiO 2 but lower in surface energy than the rutile phase of TiO 2 . Reduction of Cr 2 O 3 to Cr metal was observed after annealing with no observation of the formation of higher oxidized forms of chromium oxide like CrO 2 and CrO 3 . These findings are of general interest to researchers utilizing a protective overlayer to augment photocatalytic water splitting.

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Section: Resultsmentioning

confidence: 98%

Section: ■ Results and Discussionmentioning

confidence: 99%

Investigation of the Diffusion of Cr₂O₃ into Different Phases of TiO₂ upon Annealing

Alotabi

Gibson

Metha

et al. 2021

ACS Appl. Energy Mater.

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“…An HHV/Edwards TF500 Sputter Coater was used at a pressure of <2 x 10 -5 mbar. This process has been described in detail in previous publications [30,58]. Based on SEM measurements performed on previously prepared wafers, the thickness of the RF-TiO2 was approximately 150 nm [58], which is thick enough that the SiO2 wafer beneath would not affect any measured electron spectra.…”

Section: Methodology Substratesmentioning

confidence: 99%

“…We have previously shown this type of substrate does not feature X-ray diffraction peaks related to a specific crystal phase until modest heating is applied to the substrate under atmosphere or vacuum, upon which an anatase phase is formed and the grain size increases; strong heating under atmosphere to 1373 K for 18 hours also results in a rutile peak emerging in addition to anatase, with no further increase in grain size [58]. Anatase is the most common form used in high surface area catalysis studies.…”

Section: Introductionmentioning

confidence: 99%

“…This material is prepared by radio frequency (RF) sputtering a TiO2 wafer over a spinning substrate under high vacuum, which produces a dense, uniform, stoichiometrycontrolled layer of TiO2 which is cheaper and more readily available than TiO2 (110) [57]. RF-TiO2 has been shown to have a nanoparticulate film structure with spherical-shaped grains distributed across the substrate, with the grain size enlarging upon heat treatment [57][58][59][60].…”

Section: Introductionmentioning

confidence: 99%

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Encapsulation of Size-Selected Ru3 Clusters into RF-Deposited TiO2

Howard-Fabretto

Gorey

et al. 2022

Preprint

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In this study Ru3 clusters are deposited onto radio frequency-sputter deposited TiO2 (RF-TiO2) substrates by both solution submersion and chemical vapor deposition (CVD) of Ru3(CO)12, as well as cluster source depositions of bare Ru3. TiO2(100) and SiO2 are used as comparison surfaces with differing cluster-surface interactions. Temperature-dependent X-ray photoelectron spectroscopy (XPS), angle-resolved XPS, and temperature-dependent low energy ion scattering (TD-LEIS) are used to probe how the cluster-surface interaction changes due to heat treatment. Results show that bare Ru3 supported on SiO2 remain on the surface layer but agglomerates upon heating. Conversely, when supported on sputter-treated RF-TiO2, bare Ru3 is encapsulated by a layer of titania substrate material as-deposited. Ligated Ru3(CO)12 is also covered by a layer of titania when deposited onto sputter-treated RF-TiO2 but heat treatment is required to remove most of the ligands. TD-LEIS is used to directly measure the encapsulation of CVD Ru3(CO)12 clusters on sputter-treated RF-TiO2 and determine the substrate overlayer thickness. The overlayer was found to be 1-2 monolayers, which is thin enough for catalytic or photocatalytic reactions to occur without Ru being present in the outermost layer.

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Correlation between Photocatalysis and Antibacterial Responses of Cu‐Doped TiO₂ Films: Influence of Doping Tuning into the Oxide Matrix

Velardi

Scrimieri

Serra

et al. 2023

Physica Status Solidi (a)

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Herein, a study on the photocatalysis and antibacterial performances of Cu‐doped titania films as a function of the dopant concentration is presented. The TiO2 films are produced by sol–gel spin‐coating technique, and the doping is performed by adding different quantities of copper in the form of salt (CuSO4) during the preparation of sol. The obtained films are characterized by Raman and X‐ray diffraction spectroscopies, atomic force microscopy, and Rutherford backscattering spectrometry, to investigate on the chemical–physical properties, the quality, the composition, and the thickness. The photocatalytic activity of the films is studied by measuring the degradation of methylene blue (MB) under UV light, while Staphylococcus aureus is chosen for microbiological testing. The results show a correlation between photocatalysis and antibactericity with a rise of these two activities with increasing dopant concentrations in the films up to a given point, beyond which structural defects are introduced, promoting electron–hole recombination.

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Composition and properties of RF-sputter deposited titanium dioxide thin films

Abstract: A simple, low-cost method of preparing photocatalytic TiO2 thin films using RF plasma has been developed, offering known elemental composition, homogenous depositions, and easily modifiable crystallinity and surface properties.

Cited by 22 publications

References 41 publications

Investigation of the Diffusion of Cr₂O₃ into Different Phases of TiO₂ upon Annealing

Investigation of the Diffusion of Cr₂O₃ into Different Phases of TiO₂ upon Annealing

Encapsulation of Size-Selected Ru3 Clusters into RF-Deposited TiO2

Correlation between Photocatalysis and Antibacterial Responses of Cu‐Doped TiO₂ Films: Influence of Doping Tuning into the Oxide Matrix

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Composition and properties of RF-sputter deposited titanium dioxide thin films

Abstract: A simple, low-cost method of preparing photocatalytic TiO2 thin films using RF plasma has been developed, offering known elemental composition, homogenous depositions, and easily modifiable crystallinity and surface properties.

Cited by 22 publications

References 41 publications

Investigation of the Diffusion of Cr2O3 into Different Phases of TiO2 upon Annealing

Investigation of the Diffusion of Cr2O3 into Different Phases of TiO2 upon Annealing

Encapsulation of Size-Selected Ru3 Clusters into RF-Deposited TiO2

Correlation between Photocatalysis and Antibacterial Responses of Cu‐Doped TiO2 Films: Influence of Doping Tuning into the Oxide Matrix

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Investigation of the Diffusion of Cr₂O₃ into Different Phases of TiO₂ upon Annealing

Investigation of the Diffusion of Cr₂O₃ into Different Phases of TiO₂ upon Annealing

Correlation between Photocatalysis and Antibacterial Responses of Cu‐Doped TiO₂ Films: Influence of Doping Tuning into the Oxide Matrix