Facile formation of self-organized TiO2 nanotubes in electrolyte containing ionic liquid-ethylammonium nitrate and their remarkable photocatalytic properties
Anna Pancielejko , Paweł Mazierski , Wojciech Lisowski , Adriana Zaleska-Medynska , Klaudia Kosek , Justyna Łuczak
AbstractThe oriented TiO2 nanotube arrays (NTs) are identified as a stable, active, and recyclable photocatalytic surface. However, their photoactivity is strictly dependent on morphology (especially length), which could be controlled by anodic oxidation parameters, including electrolyte properties. To control the morphology a series of NTs were successfully synthesized by a novel approach where ionic liquid (IL), ethylammonium nitrate [EAN][NO3], was used as an addition to an organic electrolyte. Using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, diffuse reflectance UV−vis spectroscopy, and photoluminescence spectroscopy, we are able to show how electrolyte composition influences nanotubes’ surface properties and photocatalytic activity. It was found that the change in the amount of [EAN][NO3] in the electrolyte used for anodization in the range from 0.05 to 1.0 wt % affected dynamic viscosity, conductivity, and surface tension of the electrolyte and finally altered the morphology of the formed nanotubes resulting in a proportional increase of the outer diameter and tube length from 105 to 140 nm and from 6.0 to 8.1μm, respectively. The highest photoactivity (achieving high reaction rate constant, equal to k= 0.0941 min−1) and wettability were found for the sample prepared in the electrolyte containing 0.05 wt % of [EAN][NO3], revealing the improved ability to light photoabsorption and suppression of recombination rate. The increase of the contact angle from 9.3° to 13.1° with elongation of the tube diameter from 107 to 140 nm was also noted. It turned out that the IL_NTs’ surface became more hydrophobic when stored in air ambience over 7 weeks after fabrication with approximately 20−52°.
|Journal series||ACS Sustainable Chemistry & Engineering, ISSN 2168-0485, (A 40 pkt)|
|Publication size in sheets||0.6|
|Keywords in English||TiO2 nanotubes, ionic liquid, electrochemical method, anodization, phenol degradation, photoactivity, photocatalysis|
|ASJC Classification||; ; ;|
|Score||= 40.0, 30-09-2019, ArticleFromJournal|
|Publication indicators||= 0; : 2016 = 1.408; : 2017 = 6.14 (2) - 2017=6.415 (5)|
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