| 1. |
- Aromaa, Mikko, et al.
(författare)
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Atmospheric synthesis of superhydrophobic TiO2 nanoparticle deposits in a single step using Liquid Flame Spray
- 2012
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Ingår i: Journal of Aerosol Science. - : Elsevier BV. - 0021-8502. ; 52, s. 57-68
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Tidskriftsartikel (refereegranskat)abstract
- Titanium dioxide nanoparticles are synthesised in aerosol phase using the Liquid Flame Spray method. The particles are deposited in-situ on paperboard, glass and metal surfaces. According to literature, titanium dioxide is supposed to be hydrophilic. However, hydrophobic behaviour is observed on paperboard substrates but not on metal or glass substrates. Here, the water contact angle behaviour of the deposits is studied along with XRD, XPS, BET and HR-TEM. The deposits are compared with silicon dioxide deposits having, as expected, hydrophilic properties synthesised with the same method. It seems probable that the deposition process combusts some substrate material from the paperboard substrate, which later on condenses on top of the deposit to form a carbonaceous layer causing the hydrophobic behaviour of the TiO2 deposit. The similar layer does not form when depositing the nanoparticles on a metal or glass surfaces. The observations are more than purely aerosol phenomena. However, they are quite essential in nanoparticle deposition from the aerosol phase onto a substrate which is commonly utilised. (C) 2012 Elsevier Ltd. All rights reserved.
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| 2. |
- Koivikko, Niina, et al.
(författare)
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Activity and in situ DRIFT studies on vanadia catalysts during oxidative dehydrogenation of sulfur-contaminated methanol
- 2022
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Ingår i: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373. ; 318
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Tidskriftsartikel (refereegranskat)abstract
- Silica-titania (70/30) supported vanadium catalysts were prepared, characterized, and studied in oxidative dehydrogenation of sulfur-contaminated methanol. The quality of vanadia species is dependent on temperature and gas conditions during preparation, support type, support specific surface area and VOx surface density. For example, upon heating the amount of V2O5 decrease along with formation of polymeric species. Such changes may occur also during the catalytic reaction. The reaction experiments and characterization results showed that the stability of polymeric vanadia species and total acidity has a connection with better formaldehyde production performance. The best performance was observed for N2-calcined silica-titania catalyst. Easy reducibility of the catalyst, as in the case of reference catalysts, leads to further oxidation of formaldehyde.
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| 3. |
- Li, Miao, et al.
(författare)
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0.7-GHz Solution-Processed Indium Oxide Rectifying Diodes
- 2020
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Ingår i: IEEE Transactions on Electron Devices. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9383 .- 1557-9646. ; 67:1, s. 360-364
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Tidskriftsartikel (refereegranskat)abstract
- Solution-based deposition, with its simplicity and possibility for upscaling through printing, is a promising process for low-cost electronics. Metal oxide semiconductor devices, especially indium oxide with its excellent electrical properties, offer high performance compared to amorphous Si-based rivals, and with a form factor conducive to flexible and wearable electronics. Here, rectifying diodes based on an amorphous spin-coated indium oxide are fabricated for high-speed applications. We report a solution-processed diode approaching the UHF range, based on indium oxide, with aluminum and gold as the electrodes. The device was spin-coated from a precursor material and configured into a half-wave rectifier. The J-V and frequency behavior of the diodes were studied, and the material composition of the diode was investigated by X-ray photoemission spectroscopy (XPS). The 3-dB point was found to be over 700 MHz. The results are promising for the development of autonomously powered wireless Internet-of-Things systems based on scalable, low-cost processes.
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| 4. |
- Nikkanen, Juha-Pekka, et al.
(författare)
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Synthesis of carbon nanotubes on FexOy doped Al2O3-ZrO2 nanopowder
- 2014
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Ingår i: Powder Technology. - : Elsevier BV. - 0032-5910. ; 266, s. 106-112
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Tidskriftsartikel (refereegranskat)abstract
- Carbon nanotubes (CNTs) were synthesized on liquid flame sprayed (LFS) powder substrate of iron oxide doped Al2O3-ZrO2. Iron oxide doped Al2O3-ZrO2 nanopowder was produced by injecting the liquid precursor of aluminium-isopropoxide, zirconium-n-propoxide, ferrocene and p-xylene into a high temperature (similar to 3000 K) flame. The precursor solution was atomized by high-velocity H-2 flow and injected into the flame where nanopartides were formed. The collected sample was used as a substrate material for the synthesis of CNTs. The CNTs were formed on the surfaces of the substrate powder by catalyzed decomposition of CH4. The particle morphology, size, phase composition and the nature of CNTs were determined by TEM, FE-SEM, XRD, XPS, Mossbauer and Raman spectroscopy. The collected powder consists of micron-sized agglomerates with nanosized primary particles. Tetragonal zirconia was detected while alumina was amorphous. In the carbonized sample multiwalled CNTs were obtained. (C) 2014 Elsevier B.V. All rights reserved.
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| 5. |
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| 6. |
- Tuominen, Mikko, et al.
(författare)
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Superamphiphobic overhang structured coating on a biobased material
- 2016
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 389, s. 135-143
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Tidskriftsartikel (refereegranskat)abstract
- A superamphiphobic coating on a biobased material shows extreme liquid repellency with static contact angles (CA) greater than 150 degrees and roll-off angles less than 10 degrees against water, ethylene glycol, diiodomethane and olive oil, and a CA for hexadecane greater than 130 degrees. The coating consisting of titanic nanoparticles deposited by liquid flame spray (LFS) and hydrophobized using plasma-polymerized perfluorohexane was applied to a birch hardwood. Scanning electron microscopy (SEM) imaging after sample preparation by UV laser ablation of coated areas revealed that capped structures were formed and this, together with the geometrically homogeneous wood structure, fulfilled the criteria for overhang structures to occur. The coating showed high hydrophobic durability by still being non-wetted after 500 000 water drop impacts, and this is discussed in relation to geometrical factors and wetting forces. The coating was semi-transparent with no significant coloration. A self-cleaning effect was demonstrated with both water and oil droplets. A self-cleanable, durable and highly transparent superamphiphobic coating based on a capped overhang structure has a great potential for commercial feasibility in a variety of applications, here exemplified for a biobased material.
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