Europium induced point defects in SrSnO3-based perovskites employed as antibacterial agents

The antibacterial activity of Eu3+-doped SrSnO3-type materials against Staphylococcus aureus (Gram-posi-tive) and Escherichia coli (Gram-negative) bacteria is described. Two Eu3+-doped SrSnO3 perovskites -(SrEu) SnO3 and Sr(SnEu)O3 -were synthesised by a modified-Pechini method and characterised by XRD, FT-IR, FE-SEM, HR-STEM/EDX, BET, Photoluminescence (PL), UV-Vis, Q-band EPR and XPS to understand the impact of Eu doping on the materials' properties. Structural characterisations indicated that the desired perovskite phase completely crystallised after calcination at 700 degrees C. Long and short-range structural changes were observed as a function of the site-doping with Eu and calcination temperature. Small specific surface area, which varied from 8.09 to 13.28 m2/g, was observed for the samples. Nonetheless, the formation of na-noparticles under 10 nm, clusters of nanoparticles > 100 nm, and nanorods with 100-600 nm x 10-50 nm (length x width) was evidenced. Eu3+ doping led to an increase of Sn2+ and oxygen vacancies in SrSnO3 lattice, playing an essential role in the antibacterial activity. Reduced Eu2+ species were also observed. The samples had activity below 5 % against Escherichia coli, whereas (SrEu)SnO3 displayed an efficiency of 100 % after 24 h against Staphylococcus aureus at a concentration of 1 mg/mL. Our results demonstrate that a specific chemical doping with Eu induces the formation of distinct point defect (Sn2+, Eu2+ and VO center dot) in the materials, which promoted a negative surface charge that seems to have improved the redox ability and, therefore, enhanced the biocide property.(c) 2023 Elsevier B.V. All rights reserved.