Local Structures of Copper Ion Catalysts Anchored onto Various Oxide Supports and their Photocatalytic Reactivities for the Decomposition of N2O at 298 K. In Situ XAFS, Photoluminescence, EPR Investigations

Cu+/(SiO2/Al2O3), Cu+/Al2O3 and Cu+/SiO2 catalysts were prepared by a combination of the ion-exchange method and thermovacuum treatment. In-situ XANES and EXAFS investigations of the catalysts have revealed that Cu+ ions are anchored onto Al2O3 or SiO2 as planar 3-coordinate Cu+, while being anchored onto SiO2/Al2O3 as linear 2-coordinate Cu+. Photoluminescence measurements of the catalysts and their quenching by the addition of N2O indicated that the Cu+ ions interact with N2O in their photo excited state (3d94s1). UV irradiation of the catalysts in the presence of N2O led to the formation of N2 and O2 at 298 K, indicating that the photocatalytic decomposition of N2O proceeds on the Cu+ ion catalysts. Reaction proceeds more efficiently on the Cu+/(SiO2/Al2O3) catalyst than on the Cu+/Al2O3 or Cu+/SiO2 catalysts, suggesting that the 2-coordinate Cu+ species show the higher activity for the photocatalytic decomposition of N2O than the 3-coordinate Cu+ species