Optical properties of TiFe2O4 nanoparticles prepared by pulsed laser ablation in a liquid environment and their application in mercury removal

Abstract

Nanoparticles have garnered significant attention from researchers due to their enhanced properties compared to the same bulk materials. By reducing the material size, the contact area with the analyte increases exponentially, further enhancing the interaction between the sample and the target. This augmentation facilitates the acquisition of new and improved results. Titanium ferrite (TiFe₂O₄) is an alloy of particular interest to the scientific community. The amalgamation of a noble metal (Ti) with a metallic oxide forms a structure that combines the advantages of the metallic oxide with enhanced electrical conductivity due to the noble metal. This, in turn, expedites molecular interaction processes, reducing physical-chemical reaction times. In the current literature, limited information is available regarding the synthesis of TiFe₂O₄ nanoparticles, particularly through the pulsed laser ablation in liquid (PLAL) technique, known for its environmentally friendly approach to nanoparticle synthesis. With this context in mind, this work presents the synthesis and optical characterization of TiFe₂O₄ nanoparticles. TiFe₂O₄ nanoparticles were synthesized by the PLAL technique, which consisted of the ablation of a TiFe₂O₄ target immersed in a beaker containing an aqueous solution, where one solution comprised water, and the other consisted of acetone. For nanoparticle synthesis, the pulse energy was kept at 50 mJ, while the aqueous solution, wavelength, and ablation time were varied. Once synthesized, the TiFe₂O₄ nanoparticles were characterized by ultraviolet-visible (UV-Vis) spectroscopy to determine their optical properties. Using UV-Vis results, the localized surface plasmon resonance (LSPR) and band gap of each sample were determined, the latter using the Tauc method. In a sample synthesized in water, for 20 minutes and using the wavelength of 532 nm, the LSPR was observed at 270 nm. On the other hand, for the sample synthesized in acetone using the same parameters, the LSPR was observed around 330 nm and 490 nm. In addition, an analysis of the evolution over time showed that TiFe₂O₄ nanoparticles were stable when synthesized in acetone, and unstable when synthesized in water due to nanoparticle decantation over time. Finally, mercuric chloride (HgCl₂) removal experiments on agar plates of these nanoparticles were performed and quantified by Atomic Absorption Spectroscopy, where it was possible to observe a percentage of HgCl₂ elimination of around 15%.