Investigation of structural, optical, antibacterial, and dielectric properties of sol-gel and biosynthesized TiO2 nanoparticles

Abstract

This study explored the structural, optical, antibacterial, and dielectric properties of TiO2 nanoparticles synthesized using two distinct approaches: sol-gel and biosynthesis. Density functional tight binding (DFTB+) and density functional theory (DFT) calculations were employed alongside experimental techniques to gain a comprehensive understanding of the electronic-property relationships. Allium sativum peel extract was utilized for the biosynthesis method. X-ray diffraction (XRD) affirmed the anatase phase formation for both nanoparticles. Rietveld technique was employed for a detailed structural analysis. The FESEM analysis revealed the diminutive particle size of TiO2 nanoparticles with a comparable size distribution for both variants. However, the biosynthesized variant exhibited smaller average particle size (26.74 nm) than the sol-gel variant (32.22 nm). Optical studies showed an absorption redshift for the biosynthesized variant (352 nm) relative to the sol-gel variant (347 nm). The band gap energy is higher for the sol-gel variant (3.17 eV) compared to the biosynthesized variant (3.02 eV). The biosynthesized nanoparticles showed strong antibacterial activity, with inhibition zones of 15 mm against E. coli and S. flexneri bacteria. Dielectric analysis revealed that the sol-gel synthesized nanoparticles exhibited a higher dielectric permittivity of 27.80 and a lower dielectric loss of 0.37 at 1 kHz, compared to the biosynthesized nanoparticles, which showed a dielectric permittivity of 19.48 and a dielectric loss of 0.69.

Keywords

• Sol-gel
• Biosynthesis
• Allium sativum
• Band gap
• Antibacterial activity
• Dielectric properties