Synthesis and Exploration of Barium Stannate–Zirconate BaSn1–xZrxO3 (0 ≤ X ≤ 1) Solid Solutions as Photocatalysts

Employing ionic liquid-assisted microwave synthesis and moderate heat treatment allows for the preparation of otherwise difficult-to-obtain perovskite-type BaSn_1-xZr_xO₃ solid solutions (0 ≤ x ≤ 1). The impact of substituting Sn for the crystal structure, crystallinity, morphology, and photocatalytic performance was investigated. The obtained materials are characterized by X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller (BET) surface area analysis, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, and Raman and IR spectroscopy. SEM images show that the morphology of the samples varies from rods for x = 0, 0.2 to spherical for x = 0.5, 0.8, 1. Upon Zr for Sn substitution, the band gap changes from 3.1 to 5.0 eV as the valence and conduction bands move to lower and higher energies. The photocatalytic activities of the BaSn_1-xZr_xO₃ samples in the hydroxylation of terephthalic acid (TA) follow the order BaSn_0.5Zr_0.5O₃> BaSn_0.8Zr_0.2O₃> BaSnO₃> BaSn_0.2Zr_0.8O₃> BaZrO₃. The superior photocatalytic activity of BaSn_0.5Zr_0.5O₃ can be attributed to the synergistically favorable combination of a suitable band structure, band gap size, and increased surface area-to-volume ratio, resulting in a diminished crystalline particle size unattainable from samples prepared via traditional synthetic routes or without ionic liquid.