Effect of PVP molecular weight on the formation of Ag nanoparticles on echinoid-like TiO2

Ag nanoparticles were immobilized on echinoid-like TiO2 particles via an alcohol reduction process with poly(vinyl pyrrolidone) (PVP) of different molecular weights (Mw.). The sizes of Ag nanoparticles prepared by using PVP K15 (Mw.: 10,000) and K30 (Mw.: 40,000) were 12–15 nm and 19–31 nm, respectively. On the other hand, Ag nanoparticles were not observed when PVP K12 (Mw.: 3500) was used. The crystal structure of Ag nanoparticles formed on TiO2 was face-centered cubic silver phase and the chemical states of Ag nanoparticles were Ag+ and Ag0. The photocatalytic performance was enhanced by Ag deposition. Among the samples, the prepared Ag/TiO2 composite by using PVP K15 exhibited better photocatalytic activity than other composites due to its higher Ag coverage on the TiO2 surface.

Graphical abstractSchematic illustration for the effect of PVP molecular weight on the immobilization of Ag nanoparticles on echinoid-like TiO2. Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Ag nanoparticles were immobilized on the surface of echinoid-like TiO2 particles in aqueous PVP solution. ► Immobilization process was influenced by the molecular weight of PVP. ► Optimal molecular weight of PVP for the immobilization of Ag nanoparticles was found to be 10,000.