Green synthesis and characterization of titanium dioxide nanoparticles using Eucalyptus globulus leaf extract: Impacts of the mild thermal treatment

Current research efforts are directing considerable attention towards the green synthesis of nanomaterials, such as titanium dioxide nanoparticles (NPs) known for their versatile technological applications. The present work is the first to report on the synthesis of TiO₂ NPs using eucalyptus globulus leaf extract - a gentle, renewable, and non-toxic agent - in conjunction with titanium butoxide as a precursor in a mild thermal treatment. The results comprise four distinct biosynthesised material samples, each obtained by applying different techniques, including single and double-thermal treatments of NPs. Initially characterized by Fourier-transform infrared (FT-IR) and UV–visible spectroscopy, the plant extract plays a dual role in both reduction and stabilisation, leading to a remarkable NPs stability. The phytochemicals components, including phenolic and flavonoid acids, are believed to reduce the Ti⁴⁺ ions, aiding in the creation of related NPs. The successfully synthesised TiO₂ samples were characterised with diffuse reflectance UV–visible spectroscopy (DRS), FT-IR, Raman, X-ray powder diffraction (XRD), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). The findings from these investigations highlighted the pure, uniform structure, and arrangement of all NP samples, exhibiting a spherical morphology and a predominance of the anatase form. The characteristic parameters of the NPs including particle size, band gap energy, crystallinity, and lattice constants, were calculated and compared to those of commercial TiO₂. The double thermally treated sample exhibits a closer resemblance to commercial TiO₂ compared to both the singal thermally treated sample and the untreated counterpart. This suggests that the proposed mild thermal treatment can serve as an alternative approach for the effective and environmentally friendly preparation of TiO₂ NPs, ensuring good physico-chemical characteristics for a broad spectrum of advanced and sustainable applications.