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

Abstract

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 1(30 (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 Ag-0. 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.