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

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 (d9s1 → d10). Detailed photoluminescence investigations revealed that the transition metal ions exist in highly dispersed state with linear 2 coordination sphere and interact with NOx (NO and N2O) 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 N2 and O2 at ambient temperature. Detailed studies of the interaction of NOx 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 π∗ antibonding orbital of NOx initiates the decomposition of NOx into N2 and O2.