One-pot biogenic synthesis of C. limon/TiO2 with dual applications as an advance photocatalyst and antimicrobial agent

The present study portrays a facile, cost-effective, and environmentally benign way for the preparation of TiO₂ nanoparticles utilizing C. limon extract, which possesses phytochemicals as reducing and stabilizing agents. Structural characterization by XRD reveals that C. limon/TiO₂ NPs exhibit anatase-type tetragonal crystallinity. An average crystallite-size is calculated using Debye Scherrer's method (3.79 nm), Williamson-Hall plot (3.60 nm), and Modified Debye Scherrer plot (3.68 nm), which are very closely intercorrelated. The absorption peak at 274 nm (UV-visible spectrum) corresponds to the bandgap (E_g) value of 3.8 eV. The existence of different phytochemicals containing organic groups like N-H, C=O, and O-H, has been elucidated from FTIR along with Ti-O bond stretching at wavenumber 780 cm^-1. Micro-structural investigations of TiO₂ NPs using FESEM and TEM display different geometrical configurations involving spherical, pentagonal, hexagonal, heptagonal and capsule-like structures. BET and BJH analysis show mesoporous characteristics of synthesized nanoparticles with specific surface-area (97.6 m² g^-1), pore-volume (0.018322 cm³ g^-1), and mean pore-diameter (∼7.5 nm) values. In adsorption studies, the influence of reaction parameters, i.e., catalyst dosage and contact-time, for removal of Reactive Green dye is explored along with Langmuir and Freundlich models. The highest adsorption capability is ∼219 mg g^-1 for green dye. TiO₂ displays an excellent photocatalytic efficiency of ∼96% towards the degradation of reactive green dye within 180 min and excellent reusable performance. C. limon/TiO₂ is found to have an outstanding performance with a quantum yield value of 4.68 × 10^-5 molecules photon^-1 for Reactive Green dye degradation. Additionally, synthesized nanoparticles have exhibited antimicrobial activity against gram-positive Staphylococcus aureus (S. aureus) and gram-negative Pseudomonas aeruginosa (P. aeruginosa) bacteria.