Multifunctional reusable Ag-decorated ZnO nanostructured photocatalyst obtained by green synthesis

This work examined an environmentally friendly precipitation method for preparing zinc oxide decorated with silver using chitosan as a non-toxic reducing agent. The obtained powders were characterized in detail by XRPD, FESEM, HRTEM/SAED, PSD, and UV–VIS techniques. Ag/ZnO samples contained wurtzite spherical nanoparticles with an average crystallite size of about 25 nm and cubic Ag distributed on the surface. Compared to the unmodified ZnO, modification with Ag increased absorption of the visible light regarding the formation of additional charge carriers, i.e. hot electrons, due to the surface plasmon resonance effect. The recyclable Ag/ZnO photocatalyst with an optimal content of 1.5 mol. % of Ag, was successfully applied under simulated solar light for the degradation of four industrial dyes: Reactive Orange 16, Mordant Blue 9, Acid Green 25, and Ethyl Violet. High repeatability and reproducibility were confirmed. The kinetics and full mechanism of the photodegradation process through the simultaneous and synergistic influence of light-harvesting Ag and ZnO were also suggested.