Sunlight-mediated removal of endocrine disruptors from Wastewater using trimetallic core-shell Ag-TeO2@ZnO nanocomposites.

The current work emphasizes the synthesis of a trimetallic core-shell Ag-TeO2@ZnO nanocomposites by thermo-mechanical method for the efficient photocatalytic degradation of 2,4-Dichlorophenol and β-naphthol pollutants. The phase, crystallite size and morphological studies of the prepared Ag-TeO2@ZnO nanocomposites were studied by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. FE-SEM shows that Ag and TeO2 nanoparticles are deposited on the surface of ZnO nanotubes. The synthesized nanocomposite exhibited remarkable photocatalytic performance for the degradation of beta-naphthol (95.6%) in 40 min at the concentration of (0.6 mg/mL) and 2,4-DCP (99.6%) in 180 min (0.4 mg/mL) under natural sunlight. The electrochemical measurements were carried out using cyclic voltammetry and electrochemical impedance spectroscopy. Determination of reactive oxygen species (ROS) confirmed that the degradation of the pollutants by 5wt% Ag-TeO2@ZnO NCs was due to the formation of superoxide radicals. Electron paramagnetic resonance revealed the presence of sharp signals in pure ZnO nanoparticles at g ~1.9530 and oxygen vacancy peak at g~2.01 in 5 wt% Ag-TeO2@ZnO NCs. The reduction in the intensity of oxygen vacancy peak in 5 wt% Ag-TeO2@ZnO NCs resulted in higher ROS generation and, finally enhanced photocatalytic activity. To study the mechanism behind the degradation of pollutants, a scavenger test using histidine and ascorbic acid (ROS scavengers) was performed. The synthesized nanocomposites are highly stable and showed enhanced efficiency up to three cycles, confirming their reusability as a photocatalyst. We believe the synthesis method and the nanocomposite's high photocatalytic activity could be utilized extensively in wastewater treatment under natural sunlight.