Ibuprofen Photodegradation by Ag 2 O and Ag/Ag 2 O Composites Under Simulated Visible Light Irradiation

Ag2O was synthesized by the precipitation method and it was used as support to prepare Ag/Ag2O nanocomposites using different sodium citrate volumes to control the size and amount of Ag nanoparticles. Materials were characterized by X-ray powder diffraction, diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, scanning and transmission electron microscopy and nitrogen adsorption–desorption at − 196 °C analyses, respectively. Ibuprofen was selected as a probe molecule and materials were assessed as photocatalysts under simulated visible light irradiation. The SEM and TEM analysis revealed the presence of Ag nanoparticles over Ag2O support showing a size increase as citrate volume increased. By means of DRS analysis a band gap shift was observed, suggesting the formation of metallic silver during Ag impregnation while XPS results proved the co-existence of Ag0 and Ag2O composites. On the other hand, the photocatalysis results revealed the formation of intermediaries during ibuprofen photodegradation. Visible light absorption by Ag nanoparticles produced superoxide anion radicals (due to surface plasmon resonance) that enhanced the formation of intermediaries. The reaction mechanism proposed involves the generation of a Ag/Ag2O heterojunction where the metal acts as an electron scavenger decreasing the recombination of the e−–h+ pair.