Photocatalytic decomposition of N2O on Cu+/Y-zeolite catalysts prepared by ion-exchange

In situ characterization of Cu+/Y-zeolite catalysts and their photocatalytic reactivities for the decomposition of N2O into N-2 and O-2 have been investigated by means of in situ photoluminescence, XAFS, and ESR techniques along with an analysis of the reaction products. It was found that Cu(I) ions included within the nanopores of Y-zeolite exist as the [Cu(I)--Cu(I)] dimer species as well as the isolated Cu(I) monomer species, their ratio being much dependent on the SiO2/Al2O3 ratio of Y-zeolite. UV irradiation of these Cu+/Y-zeolite catalysts in the presence of N2O led to the photocatalytic decomposition of N2O into N-2 and O-2 at temperatures as low as 275 K. The electronically excited state of Cu(I) ion (3d(9)4s(1) state) plays a vital role in the photocatalytic decomposition of N2O into N-2 and O-2. The photocatalytic reactivity of these Cu+/zeolite catalysts was found to be strongly affected by the local structure of the Cu(I) ions which could easily be modified by changing the SiO2/Al2O3 ratio of Y-zeolite. The isolated linear 2 coordinated Cu(I) monomer species formed on Y-zeolite having a moderate SiO2/Al2O3 ratio exhibited a high photocatalytic reactivity for the direct decomposition of N2O into N-2 and O-2, clearly showing the importance of the coordinative unsaturation of the active sites.