Synthesis, characterization, photocatalytic, and antimicrobial activity of ZrO2 nanoparticles and Ag@ZrO2 nanocomposite prepared by the advanced oxidative process/hydrothermal route

Abstract

ZrO2 nanoparticles (ZrO2 NPs) and Ag@ZrO2 nanocomposite (Ag@ZrO2 NCs) were prepared from zirconium (IV) butoxide in the absence of base or acid mineraliser by the advanced oxidation processes (AOP) and subsequent hydrothermal treatment. Samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), Raman, Photoluminescence (PL), Fourier transform infrared (FTIR), and diffuse reflectance spectroscopy (DRS). XRD and Raman analyses confirmed ZrO2 NPs and Ag@ZrO2 NCs tetragonal crystalline phase synthesized at 200 °C for 1 h. HRTEM images of ZrO2 NPs and Ag@ZrO2 NCs after treatment at 200 °C indicated small nanoparticles with characteristic size of 5–8 nm (ZrO2) and 40–50 nm (Ag NPs). It was found that Ag@ZrO2 NCs showed outstanding photocatalytic activity in photodegradation Rhodamine B dye compared with pure ZrO2 NPs. Antibacterial activity tests of ZrO2 NPs and Ag@ZrO2 NCs were carried out using E. coli and S. aureus as model strains of Gram-negative and Gram-positive bacteria, respectively. Ag@ZrO2 NCs were capable of efficiently growth inhibition of bacteria cultures in more than 75% E. Coli compared to ZrO2 NPs that exhibited <10% instead. However, at the same concentration (for example 0.25 mg/mL) we found that both ZrO2 NPs and Ag@ZrO2 NCs were significantly more effective against S. aureus in comparison with E. coli showing bacterial growth inhibition higher than 90% for S. aureus. Morphological observation of bacterial cells by scanning electron microscopy (SEM) revealed that nanoparticles and nanocomposite caused irreversible damage to the cell membrane.