Synthesis, analysis and characterization of structural, optical, photoluminescence, chromaticity, antimicrobial, antioxidant, and hemolysis properties of SnO2-NiO nanocomposites

SnO2-NiO nanocomposites were synthesized through co-precipitation utilizing two distinct tin oxide precursors (Sn powder and tin dichloride dihydrate) along with a nickel precursor (nickel nitrate). XRD analysis validated the presence of tetragonal rutile SnO2 and face-centered cubic NiO phases, with increasing temperatures (450–650 °C) leading to improved crystallinity and increased crystallite size. FE-SEM analysis displayed average particle sizes ranging from 10-37 nm, depending on precursor and calcination temperature. EDX confirmed variations in elemental composition of Sn, O, and Ni with increasing calcination temperature. Optical studies of SnO2-NiO revealed a reduction in the band gap and photoluminescence (PL) emission intensity with increasing calcination temperature, accompanied by strong PL peaks at 393, 436, and 465 nm, corresponding to UV and blue emissions. The chromaticity diagrams of all calcined SnO2-NiO nanocomposites showed blue colour emissions. The antibacterial efficacy of SnO2-NiO nanocomposites was evaluated against E. coli and S. aureus. The nanocomposites demonstrated comparatively larger zones of inhibition against E. coli than against S. aureus, suggesting superior antibacterial effectiveness. Additionally, antioxidant and hemolysis tests were performed to evaluate the free radical scavenging capacity and hemocompatibility of the nanocomposites, respectively. The findings revealed a notable variation with respect to calcination temperature. In particular, as the calcination temperature increased, there was a decrease in the zone of inhibition, free radical scavenging activity, and hemolytic percentage. This reduction is likely attributed to the enhanced crystallinity of the nanocomposites at elevated temperatures.