Effect of <i>Terminalia chebula</i> Seed Extract Concentration on the Structural, Optical, and Photocatalytic Properties of Biosynthesized SnO ₂ Nanoparticles

ABSTRACT In this study, tin oxide (SnO 2 ) nanoparticles (NPs) were biosynthesized using Terminalia chebula seed extract at varying concentrations of 3%, 4%, and 5%, highlighting the critical role of extract concentration in tuning the properties of the resulting nanomaterials. Structural and morphological analyses confirmed the formation of tetragonal SnO 2 NPs with particle size decreasing from 12.3 to 11.5 nm as the extract concentration increased. Characterization by X‐ray diffraction (XRD), UV–visible spectroscopy (UV–vis), High‐transmission electron microscopy (HR‐TEM), and Brunauer–Emmett–Teller (BET) analysis revealed that higher extract concentrations yielded NPs with reduced crystallite size, narrower bandgaps, and increased surface areas—properties that collectively enhanced their photocatalytic performance. The 5% extract‐derived SnO 2 NPs exhibited superior efficiency, degrading 92.5% of methylene blue (MB) within 60 min under UV irradiation, compared to 81.6% by the 3% extract‐derived sample. These findings underscore the significance of extract concentration in tailoring NP characteristics, enabling improved environmental applications through enhanced photocatalytic activity.