In situ characterization of the Ag+ ion-exchanged zeolites and their photocatalytic activity for the decomposition of N2O into N2 and O2 at 298 K

Ag+ ion-exchanged zeolites (Ag+/ZSM-5, Ag+/Y) were prepared by an ion-exchange method. XAFS measurements showed that Ag+ ion exists in a two-coordinate sphere within the pore structure of ZSM-5, while aggregated Ag species (Ag-n(0) or Ag-m(n+) clusters) are formed within Y-zeolite. It was found that photocatalytic decomposition reaction of N2O into N-2 and O-2 at 298 K proceeds much efficiently on Ag+/ZSM-5 as compared to Ag+/Y. In situ UV-Vis, photoluminescence and Fr-IR investigations revealed that N2O adsorbs onto the isolated Ag+ ion to form Ag+-N2O adduct within ZSM-5, and the photoexcitation of thus formed Ag+-N2O adduct is the most important step of the photocatalytic decomposition reaction of N2O. (C) 2003 Elsevier Science B.V. All rights reserved.