Physicochemical Variation of Tin Oxide (SnO2) Nanoparticles Induced by Reduction and Stabilization with Different Phytochemicals
摘要
Green synthesis using plant-derived phytochemicals offers a sustainable route for producing metal oxide nanomaterials. In this study, tin oxide nanoparticles (SnO2 NPs) were synthesized via a phytochemical-mediated approach using extracts from four flavonoid-rich spices: ginger (Zingiber officinale), turmeric (Curcuma longa), coriander (Coriandrum sativum), and fennel (Foeniculum vulgare). Liquid chromatography–mass spectrometry revealed distinct phytochemical profiles among the extracts, comprising varying proportions of polyphenols, flavonoids, and terpenoids. Despite identical synthesis conditions, these compositional differences correspond to variations in the SnO2 properties. X-ray diffraction and Raman spectroscopy showed the formation of tetragonal SnO2 in all samples, with crystallite sizes varying notably, ginger (45.9 nm), coriander (59.8 nm), turmeric (70.1 nm), and fennel (80.8 nm). Diffuse reflectance spectroscopy indicated reduced optical bandgaps (2.62–3.04 eV), suggesting the presence of defect- and carbon-associated states. Furthermore, BET analysis showed that ginger-derived SnO2 NPs possessed the highest specific surface area (103.46 m2 g–1), followed by turmeric (85.28 m2 g−1), coriander (84.35 m2 g−1), and fennel (68.39 m2 g−1). Under UV irradiation, the photocatalytic degradation of methylene blue over 90 min varied by extract, with SnO2-Ginger exhibiting the highest degradation efficiency (13%) and rate constant (1.48 × 10–3 min−1), while SnO2-Fennel demonstrated the lowest (5.7%; 0.64 × 10–3 min−1). These findings suggest that the balance of phytochemical reducing and stabilizing agents could influence nucleation, growth, and defect formation in green-synthesized SnO2. Finally, this work demonstrates the relationship between extract composition and nanoparticle characteristics, highlighting the potential role of phytochemical selection in modulating the physicochemical properties of metal oxide photocatalysts.