Graphene oxide-integrated SnO2 nanocomposites with tunable structural, morphological, optical, and antibacterial properties

Graphene oxide (GO)–incorporated tin oxide (SnO _2 ) nanocomposites have attracted significant attention due to their tunable structural, optical, and biological properties. In this work, pristine and GO-integrated SnO _2 nanocomposites were synthesized via a co-precipitation method with varying GO concentrations to investigate their physicochemical characteristics and antibacterial performance. X-ray diffraction analysis confirmed the formation of a tetragonal cassiterite SnO _2 structure with an average crystallite size of approximately 26 nm. FESEM and TEM studies revealed well-distributed GO–SnO _2 nanocomposites, while HRTEM analysis confirmed their crystalline nature with d-spacing values consistent with XRD results. Raman spectroscopy identified characteristic vibrational modes (A _1 g, B _2 g, and Eg), indicating structural integrity and defect-related features, whereas FTIR spectra exhibited prominent Sn–O stretching vibrations at 604 and 462 cm ^−1 . TGA/DTA analysis demonstrated good thermal stability with minimal weight loss beyond 400 °C. UV–Visible spectroscopy and Tauc analysis revealed a reduction in band gap upon GO incorporation, attributed to the formation of interstitial energy levels and enhanced electronic interaction. EDS analysis showed increased carbon content and notable variations in the Sn–O ratio with increasing GO concentration, suggesting modified surface reactivity. Antibacterial activity evaluated against Staphylococcus aureus , Escherichia coli , Klebsiella sp., and Pseudomonas sp. showed a significant enhancement for GO-integrated SnO _2 samples, with a maximum increase of approximately 66.7% against Pseudomonas sp and 37.5% against E.coli , calculated from zone of inhibition measurements. This enhancement is attributed to increased reactive oxygen species generation and effective bacterial membrane disruption induced by GO incorporation. The study highlights the potential of GO–SnO _2 nanocomposites as advanced antibacterial materials, contributing to Sustainable Development Goals SDG 3 (Good Health and Well-being) and SDG 9 (Industry, Innovation, and Infrastructure).