The Impact of Different Green Synthetic Routes on the Photocatalytic Potential of FeSnO₂ for the Removal of Methylene Blue and Crystal Violet Dyes under Natural Sunlight Exposure

FeSnO₂ nanocomposites were synthesized via the green method using aqueous leaf extracts of Lawsonia inermis and Phyllanthus embilica plants. The role of polyphenols based on reduction potentials for the synthesis of FeSnO₂ was also highlighted. The synthesized materials were examined by using TGA and DSC, FT-IR, XRD, and SEM with EDX analysis. Tetragonal rutile and distorted hexagonal structures were observed in SEM images of the FeSnO₂ nanocomposites and compared with an FeSnO₂ nanocomposite prepared using the sol-gel method. Scherer’s formula yielded crystallite sizes of 29.49, 14.54, and 20.43 nm; however, the average crystallite size assessed employing the Williamson–Hall equation was found to be 20.85, 11.30, and 14.86 nm by using the sol-gel and green techniques, using extracts from Lawsonia inermis and Phyllanthus embilica. The band gap was determined by using the Tauc and Wood equations, and photocatalytic activity was analyzed to determine the degradation of methylene blue (MB) and crystal violet (CV) under the illumination of natural sunlight. It was observed that the sample prepared by means of the green method using the leaf extract of Lawsonia inermis showed the best photocatalytic activity of 84%, with a particle size of 14.54 nm, a 3.10 eV band gap, and a specific surface area of 55.68 m²g⁻¹.