Green Synthesis of Titanium Dioxide Nanoparticles: Characterization and Evaluation of Their Potential for Photocatalytic and Dielectric Applications

This study investigated the dielectric and photocatalytic properties of green-synthesized titanium dioxide nanoparticles (TiO₂ NPs), which are widely utilized semiconductor materials known for their excellent optical, structural, and electronic characteristics. The TiO₂ NPs were synthesized via a green precipitation method from the aqueous extract of <i>Cymbopogon proximus</i>. A comprehensive set of analytical techniques-UV-Vis spectroscopy, XRD, FTIR, TEM, EDX, and DLS-was employed to determine their optical response, crystalline structure, functional groups, morphology, elemental composition, and particle size distribution. UV-Vis analysis revealed a characteristic absorption peak at 327 nm, and the band gap energy, calculated via the Tauc plot method, was 3.16 eV. The XRD results confirmed the formation of a tetragonal TiO₂ phase with an average crystallite size of approximately 4 nm. TEM images further supported the spherical to quasitetragonal morphology and revealed that the aggregated clusters formed conjoint nanostructures. The photocatalytic activity of the TiO₂ NPs was evaluated using a 0.5 mM RhB dye solution under UV-visible irradiation. The synthesized nanoparticles achieved a photodegradation efficiency of 97% after 50 h, with a corresponding rate constant of 0.073402 h^-1, indicating their potential for effective photocatalytic pollutant removal. Furthermore, the dielectric behavior of the TiO₂ NPs was examined at room temperature. The material exhibited a high dielectric constant at low frequencies due to interfacial (Maxwell-Wagner) polarization, along with frequency-dependent AC conductivity attributed to charge-carrier hopping mechanisms. These dielectric properties, combined with strong photocatalytic performance, underscore the suitability of green-synthesized TiO₂ NPs for applications in environmental remediation, energy-storage devices, and advanced technologies.