Photoluminescence properties and photocatalytic reactivities of Cu~+/zeolite and Ag~+/zeolite catalysts prepared by the ion-exchange method

摘要

Transition metal ions (Cu~+, Ag~+) incorporated within the cavities of zeolites by an ion-exchange method exhibit unique photoluminescence under UV irradiation due to the inner shell type electronic transition (d~9s~1 → d~(10)). Detailed photoluminescence investigations revealed that the transition metal ions exist in highly dispersed state with linear 2 coordination sphere and interact with NO_x (NO and N_2O) in their photoexcited states. In fact, Cu~+ and Ag~+ ions within zeolites show an efficient and unique photocatalytic performance for the decomposition of NO into N_2 and O_2 at ambient temperature. Detailed studies of the interaction of NO_x with the excited states of these metal ions indicated that an electron transfer from the s orbital of the excited state of Cu~+ or Ag~+ ions into the μ* antibonding orbital of NO_x initiates the decomposition of NO_x into N_2 and O_2.