Synthesis of a novel Z-scheme Ag/WO3/g-C3N4 nanophotocatalyst for degradation of oxytetracycline hydrochloride under visible light

Abstract

In this work, Ag/WO3/g-C3N4 (AWC) nanocomposites were successfully prepared via a hydrothermal method. Oxytetracycline hydrochloride (OTC) was used to evaluate the photocatalytic activity of the photocatalysts under visible light. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectra (Raman), scanning electron microscope (SEM), Ultraviolet–visible spectroscopy (UV–vis DRS), photocurrent density (I-t) and electrochemical impedance spectra (EIS). The results showed that WO3 and Ag nanoparticles were coupled with g-C3N4 successfully. Comparing with pure WO3 or g-C3N4, the visible light absorption region of AWC composites was effectively broadened. The photocatalytic performance experiment illustrated that AWC-2 composite had the highest photocatalytic activity, and 97.74% of OTC (10 mg/L) was degraded in 60 min with 0.4 g/L of AWC-2. The radical scavenging experiments indicated that the superoxide radical (•O2−) and hydroxyl radical (•OH) were the most important active species for OTC oxidation. The five cycle photocatalysis experiment further proved that AWC is a stable photocatalyst for degradation of OTC. Finally, the possible degradation mechanism of Z-scheme heterostructure photocatalysis was proposed according to the experimental results.