Photocatalytic and antibacterial activities of Tl–Hg–I nanocomposites: sonochemical synthesis and characterization

Abstract

Efforts to find new and practical solutions to improve water quality and treatment of industrial effluents are ongoing. In this study, Tl₄HgI₆/HgI₂ nanocomposites were synthesized by a rapid ultrasonic method to investigate their photocatalytic and antibacterial activity. Various synthesis conditions such as changes in the ratio of precursors, use of surfactants, and changes in the power and time of sonication to achieve particles with optimal size and morphology were performed. X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) analysis confirmed the purity and formation of the nanocomposite. Optimal nanoparticles in terms of size and morphology were selected by examining the images obtained from scanning electron microscopy (SEM) analysis. The nanocomposites obtained in the presence of PVP (polyvinylpyrrolidone) as a surfactant (sample no. 8) were selected as the optimal sample. Transmission electron microscopy (TEM), differential reflectance spectroscopy (DRS), Raman, N₂ adsorption/desorption analyzes were performed for the optimal sample to evaluate the properties of nanocomposites. The band-gap for Tl₄HgI₆/HgI₂ nanocomposites was calculated to be about 2.3 eV for HgI₂ and 3.1 eV for Tl₄HgI₆. The optimal sample was used to evaluate the photocatalytic activity for decolorizing an aqueous solution of six different organic dyes. Finally, for rhodamine B, the decolorization was about 80%. Also, Tl₄HgI₆/HgI₂ nanocomposite showed a significant inhibition zone in the antibacterial test. The maximum inhibition diameter of 50 mm was obtained against Streptococcus pyogenes. The results showed that Tl₄HgI₆/HgI₂ nanocomposites have good potential for many industrial applications.