Novel ZnO/Ag nanohybrids prepared from Ag+-doped layered zinc hydroxides as highly active photocatalysts for the degradation of dyes and Ciprofloxacin

The design and the synthesis of highly active nanohybrid photocatalysts for environmental remediation is a topical issue in the context of sustainable development. The hybridization of a semiconductor with noble metal nanoparticles (NPs) has been demonstrated to be a versatile strategy to restrict the recombination of photogenerated electron-hole pairs and thus increase the photocatalytic activity. However, the uniform association of nanosized metal particles with ZnO NPs remains a challenge. Herein, a novel synthesis of ZnO NPs hybridized with Ag(0) NPs is presented. Ag+-doped layered zinc hydroxides (LZHs) were prepared in aqueous solution in the presence of triethanolamine and subsequently Ag+ ions were photoreduced into metallic Ag NPs embedded into LZHs. The LZHs not only promote the dispersion of Ag NPs but also limit their growth. The Ag(0)-doped LZHs obtained after hydrothermal treatment was finally transformed into ZnO/Ag nanohybrids by a mild thermal treatment at 300 °C for 5 min, which allows high interface coupling between ZnO and Ag NPs. ZnO associated with 3 mol% Ag exhibits the highest photocatalytic activity for the degradation of dyes (Rhodamine B and Remazol Brillant Blue R) and of the Ciprofloxacin antibiotic. The high photocatalytic performance of the ZnO/Ag(3) nanohybrid originates from the charge transfer in the ZnO/Ag nanohybrid and from the enhanced harvesting of visible light. The ZnO/Ag(3) photocatalyst also exhibits a high practical stability, indicating its great potential for real photocatalytic applications.