One-step synthesis of hexylresorcinol calix[4]arene-capped ZnO-Ag nanocomposites for enhanced degradation of organic pollutants.

In this study, hexylresorcinol calix[4]arene (HRCA) is introduced into the reaction system, and HRCA-capped ZnO-Ag nanocomposites are prepared via a simple one-step reflux method. HRCA is used not only as a reducing agent for deoxidizing Ag to Ag, but also as a protectant for wrapping around the microstructure of the formed ZnO-Ag. The prepared samples are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and water contact angle. The Ag nanoparticles and ZnO adhere to each other and HRCA molecules encapsulate on the surface of ZnO-Ag nanocomposites. HRCA-capped ZnO-Ag nanocomposites with different Ag contents are investigated for use in photodegradation of organic pollutants (rhodamine B (RhB) and levofloxacin hydrochloride). The sample with 10.20 mol% Ag, denoted as ZA3, exhibits the highest catalytic activity for photodegradation of RhB and levofloxacin hydrochloride. Moreover, ZA3 exhibits high stability during photodegradation of organic pollutants even after multiple reuses. The possible photocatalytic mechanism is discussed. We believe that O and h are the chief active species responsible for the photocatalytic activity of HRCA-capped ZnO-Ag nanocomposite system. HRCA-capped ZnO-Ag nanocomposite is expected to be an effective photocatalyst with potential application to sewage treatment under sunlight.