0507778 - ÚACH 2020 RIV GB eng J - Journal Article
Bakardjieva, Snejana - Mareš, Jakub - Fajgar, Radek - Zenou, V. Y. - Malečková, M. - Chatzisymeon, E. - Bíbová-Lipšová, Hana - Jirkovský, Jaromír
The relationship between microstructure and photocatalytic behavior in lanthanum-modified 2D TiO2 nanosheets upon annealing of a freeze-cast precursor.
RSC Advances. Roč. 9, č. 40 (2019), s. 22988-23003. ISSN 2046-2069. E-ISSN 2046-2069
R&D Projects: GA ČR(CZ) GA18-15613S; GA MŠMT(CZ) LM2015073
Institutional support: RVO:61388980 ; RVO:67985858 ; RVO:61388955
Keywords : lyophilized aqueous colloids * lattice distortion * salicylic-acid * degradation * titania * 4-chlorophenol
OECD category: Inorganic and nuclear chemistry; Inorganic and nuclear chemistry (UCHP-M); Physical chemistry (UFCH-W)
Impact factor: 3.119, year: 2019 ; AIS: 0.515, rok: 2019
Method of publishing: Open access
DOI: https://doi.org/10.1039/c9ra03940f

Titanium dioxide modified with 3 wt% La was prepared via a green freeze-casting method, and its photocatalytic activity was tested in terms of its ability to degrade 4-chlorophenol (4-CP) and remove total organic carbon (TOC). Under annealing conditions, the freeze-cast precursor was transformed into an La-modified anatase with a well-defined 2D TiO2 nanosheet morphology. Rietveld refinement of the X-ray diffraction patterns confirmed the substitutional nature of the La cation that induced local structural variations and involved subtle ion displacement in the TiO2 lattice due to the ionic size effect. Despite nearly identical tetragonal structures, replacement of Ti with La alters the photocatalytic activity through a reduction in band gap energies and an increase in charge carrier mobility. Material annealed at 650 degrees C exhibited the highest photocatalytic performance and achieved efficient TOC removal. Upon annealing at 800 degrees C, nanoscale lanthanum-enriched regions were generated due to the diffusive migration of La cations and phase transition from anatase to rutile. The La3+ cation, acting as a structural promoter, supported 2D TiO2 growth with well controlled crystallite size, surface area and porosity. La3+ could be regarded as a potential electronic promoter that can reduce the band gap of 2D TiO2 nanosheets and can provide a signature of the electron transfer and carrier charge separation. Both methods, kinetics of degradation of 4-CP and TOC, provided similar results, revealing that the photocatalytic activity under UV light irradiation increased in the order 950C < 500 degrees C < 800 degrees C < 650 degrees C < TiO2-P25.
Permanent Link: http://hdl.handle.net/11104/0298752