Silver decorated ZnO photocatalyst for effective removal of reactive red azo dye and ofloxacin antibiotic under solar light irradiation

Abstract It is well accepted that fast electron-hole recombination is the main drawback affecting low performance of the ZnO photocatalyst which is active only under UV light covering less than 5% of sunlight. To overcome this problem, the promising strategy based on decoration of noble metals on ZnO photocatalyst has been proposed. In the present study, incorporation of silver from 1 to 5 wt% was performed. The 5Ag-ZnO photocatalyst, containing 5 wt% silver, showed hexagonal phase with excellent visible-light-responsive performance and improved anti-photocorrosion property. The complete removal of reactive red dye and ofloxacin antibiotic was achieved after 25 and 80 min, respectively. The enhanced photoactivity is attributed to great electron-hole separation efficiency at the interface of the photocatalyst. Decoration of the metallic silver on ZnO photocatalyst leads to the creation of the Schottky barrier at the silver/ZnO interface resulting in enhancement of the quantum efficiency and improvement of the photocatalytic activity. In addition, incorporation of silver metal also leads to red shift in the adsorption band toward the visible region due to the local surface plasmon resonance (LSPR) effect of the metallic silver on the surface of ZnO. The photocatalyst shows structural stability after three cycles of use. The 5Ag-ZnO photocatalyst retains its great efficiency even after the third cycle suggesting its excellent reusability. The present research provides a novel route for fabrication of a promising silver decorated ZnO for detoxification of organic pollutants in wastewater.