Green Synthesis of Tin Oxide (SnO₂) Nanoparticles from Senna alata Leaves Extract

The plant-mediated synthesis of metal oxide nanoparticles is an eco-friendly and sustainable approach for hazardous chemical- and energy-expending protocols. Chemically synthesized methods often use toxic reagents and are biological hazards, whereas physical methods require special equipment and may lead to the loss of control of the particles. In this work, fresh Senna alata leaf extract was used to synthesize SnO₂ nanoparticles via a green route as reducing, stabilizing, and capping agents. A metal precursor (1.0 M tin chloride) was utilized. The prepared nanoparticles were characterized via X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and ultraviolet‒visible (UV‒Vis) spectroscopy to investigate their structural, morphological and optical properties. As derived from the XRD measurements, a major peak was detected for the (002) plane, and the average crystallite size was 8.25 nm, with a d-spacing value of approximately 0.2575 Å, corresponding to nanocrystalline SnO₂, which confirmed its successful formation. The FTIR analyses revealed characteristic molecular vibrations related to structures of SnO₂. Scanning and transmission electron microscopic evaluations revealed crystallites with distinctive morphologies of SnO₂ nanoparticles. The absorption edge is approximately 300 nm, and the bandgap energy is estimated to be 4.57 eV via optical characterization. The preferred (002) orientation, nanoscale crystallinity and wide bandgap make the synthesized SnO₂ nanoparticles multifunctional. These properties render them excellent candidates for optoelectronic and environmental sensors, energy storage applications, and anticorrosion coatings, providing a versatile architecture for designing next-generation nanotechnologies.