Fabrication and photoactivity of ionic liquid-TiO2 structures for efficient visible-light-induced photocatalytic decomposition of organic pollutants in aqueous phase

Anna Gołąbiewska; Marta Paszkiewicz-Gawron; Aleksandra Sadzińska; Wojciech Lisowski; Ewelina Grabowska; Adriana Zaleska-Medynska; Justyna Łuczak

doi:10.3762/bjnano.9.54

Fabrication and photoactivity of ionic liquid-TiO₂ structures for efficient visible-light-induced photocatalytic decomposition of organic pollutants in aqueous phase

Beilstein J Nanotechnol. 2018 Feb 14:9:580-590. doi: 10.3762/bjnano.9.54. eCollection 2018.

Authors

Anna Gołąbiewska¹, Marta Paszkiewicz-Gawron¹, Aleksandra Sadzińska², Wojciech Lisowski³, Ewelina Grabowska¹, Adriana Zaleska-Medynska¹, Justyna Łuczak²

Affiliations

¹ University of Gdansk, Faculty of Chemistry, Department of Environmental Technology, Wita Stwosza 63, 80-308 Gdansk, Poland.
² Gdansk University of Technology, Chemical Faculty, Department of Chemical Technology, Narutowicza 11/12, 80-233 Gdansk, Poland.
³ Institute of Physical Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Poland.

Abstract

To investigate the effect of the ionic liquid (IL) chain length on the surface properties and photoactivity of TiO₂, a series of TiO₂ microspheres have been synthesized via a solvothermal method assisted by 1-methyl-3-octadecylimidazolium chloride ([ODMIM][Cl]) and 1-methyl-3-tetradecylimidazolium chloride ([TDMIM][Cl]). All as-prepared samples were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS), scanning transmission microscopy (STEM) and the Brunauer-Emmett-Teller (BET) surface area method, whereas the photocatalytic activity was evaluated by the degradation of phenol in aqueous solution under visible light irradiation (λ > 420 nm). The highest photoefficiency (four times higher than pristine TiO₂) was observed for the TiO₂ sample obtained in the presence of [TDMIM][Cl] for a IL to TiO₂ precursor molar ratio of 1:3. It was revealed that interactions between the ions of the ionic liquid and the surface of the growing titanium dioxide spheres results in a red-shift of absorption edge for the IL-TiO₂ semiconductors. In this regard, the direct increase of the photoactivity of IL-TiO₂ in comparison to pristine TiO₂ was observed. The active species trapping experiments indicated that O₂^•- is the main active species, created at the surface of the IL-TiO₂ material under visible-light illumination, and is responsible for the effective phenol degradation.

Keywords: TiO2; heterogeneous photocatalysis; ionic liquids; visible light catalysis.