PHOTOCATALYSIS OF CATIONS INCORPORATED WITHIN ZEOLITES- The Local Structures and Excited States of the Cu (I) and Ag (I) Species and Their Photocatalytic Reactivities

摘要

Transition metal ions (Cu~+, Ag~+) incorporated within the c; vities of zeolites by an ion-exchange method showed an efficient and unique photocatalytic performance for the decomposition of NOx (NO, N_2O) into N_2 and O_2 at 275 K. In-situ ESR, UV-VIS, photoluminescence and XAFS (XANES and FT-EXAFS) investigations revealed that the transition metal ions exist in a highly dispersed state with a linear 2-coordination sphere within the pores of the ZSM-5 zeolite, the local struc ures of the metal ions being significantly affected by the change in the kinds of zeolites. Detailed studies of the interaction of NO with the excited states of these metal io is clearly indicated that the unique inner shell type excitation states of these metal ions play a significant role in the photocatalytic decomposition of NO, i.e., an electron transfer from the s orbital of the excited state of Cu~+ or Ag~+ ions into the π~* antibonding orbital of NO initiates the decomposition reaction of NO.