Estanatos/titanatos com propriedades fotocatalíticas e antimicrobianas

Abstract

In this work, perovskite-type oxides of pure and Eu3+-doped strontium stannate (SrSnO3), and pure and combined Zn2SnO4 and Zn2TiO4 spinels were synthesized in order to obtain a solid solution of Zn2SnxTi1-xO4 (0 ≤ x ≥ 1) using the modified Pechini method. In the case of perovskites, the impact of Eu3+ doping on the Sr2+ and Sn4+ sites in SrSnO3 on their structural and electronic properties was evaluated, which were correlated with photocatalytic efficiency, as well as the antibacterial activity of these materials against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) bacteria. The samples were characterized by XRD, IR, FE-SEM, HR-STEM/EDX, BET, Photoluminescence (FL), UV-Vis, EPR (Q-band), and XPS. Doping with Eu3+ led to an increase in Sn2+ and oxygen vacancies in the SrSnO3 lattice, playing an essential role in antibacterial activity; reduced Eu2+ species were also observed. The samples showed activity below 5% against Escherichia coli, while (SrEu)SnO3 showed 100% efficiency after 24h against Staphylococcus aureus. In the spinel samples, the effect of Sn insertion on structural, morphological, and electronic characteristics, as well as photoluminescent, photocatalytic, and antimicrobial properties, was evaluated. Rietveld structural refinement analyses, infrared and Raman spectroscopies, morphological and textural analyses were used. Zn2SnO4 showed greater photocatalytic efficiency, with 100% decolorization of methylene blue and brilliant victory blue dyes after UV irradiation for 300 min and 30 min, respectively. It also exhibited high antibacterial inhibition against the Gram-positive bacterium (S. aureus), suggesting that surface characteristics are key to its activity.