SrSnO₃:Cu²⁺/Sn_1-xZr_xO₂: Structural and photocatalytic properties

Full text: Perovskites with ASnO₃ stoichiometry (A=Sr, Ba and Ca) have been studied due to its interesting optical, electrical, magnetic and photocatalytic properties [1,2]. On the other hand, oxides as SnO₂ and ZrO₂ have been used as catalysts or catalytic supports for the photocatalytic degradation of organic pollutants. In the present work, catalytic supports with the composition Sn_1-xZr_xO₂ (x = 0, 5 and 10 at %) were synthesized by solid state reaction, and SrSnO₃:Cu perovskite was impregnated on their surfaces using the modified Pechini method. The materials were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), Raman spectroscopy and UV-visible spectroscopy. In spite of Cu addition into SrSnO₃ structure, no meaningful changes in the long-range order were noticed. Peaks were observed in the XRD patterns, in agreement to the orthorhombic structure of SrSnO₃ (ICDD 01-77-1798). SnO₂, Sn_0.95Zr_0.05O₂, Sn_0.90Zr_0.10O₂ presented tetragonal phase (ICDD 00-041-1445). After impregnation, only the three most intense perovskite peaks were observed, assigned to the (200), (220) and (312) planes. Bands assigned to the perovskite were also observed in the IR spectra and Raman spectra of the impregnated materials. The materials were applied in the photocatalytic degradation of the Remazol Golden Yellow azo-dye (RNL) under UV irradiation. A discoloration of 58% after 4 h of irradiation was observed for SrSnO₃, while only 9% was obtained using the Cu-doped SrSnO₃, probably due to electron-hole recombination processes. The impregnation of the SrSnO₃ on the supports did not improve its photocatalytic activity, while a higher activity was observed for the SrSnO₃:Cu sample, for which 36% of discoloration after impregnation on Sn_0.90Zr_0.10O₂. References: [1] Z. Kotan and M. Ayvacikli, Journal of Alloys and Compounds 581, 101-108 (2013). [2] Ž. Dohnalová and N. Gorodylova, Ceramics International 40, 12637-12645 (2014). (author)