Ag+/ZSM-5 catalysts were prepared by an ion-exchange method and characterized by in-situ XPS, XAFS (XANES and EXAFS), UV−Vis, photoluminescence, and FT-IR investigations. These Ag+/ZSM-5 catalysts were found to exhibit an UV absorption band at around 190 nm due to the isolated Ag+ ions. The addition of N2O molecules leads to a shift in this band to 220 nm due to the adsorption of N2O on the Ag+ ions. The adsorption of N2O on the Ag+ ions could also be clarified by the appearance of characteristic FT-IR bands at 2251 cm-1. UV irradiation of the Ag+/ZSM-5 catalysts in the presence of N2O led to the photocatalytic decomposition of N2O into N2 and O2 at temperatures as low as 298 K. It was found that UV light at around 200−250 nm is effective for the reaction, suggesting that excitation of the isolated Ag+ ion plays a significant role in the photocatalytic decomposition of N2O.

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Cu(I) (Cu + ) ion catalysts anchored onto various oxides (SiO 2 ‚Al 2 O 3 , Al 2 O 3 , and SiO 2 ) were prepared by the combination of an ion-exchange method and a thermovacuum treatment. XAFS (X-ray absorption fine structure) investigations revealed that Cu + ions exist as linear two-coordinate Cu + on SiO 2 ‚Al 2 O 3 , while they exist as planar three-coordinate Cu + on Al 2 O 3 or SiO 2 . It was also found that the typical photoluminescence observed at 430 nm for the Cu + /(SiO 2 ‚Al 2 O 3 ) catalyst and that observed at 510 nm for the Cu + /Al 2 O 3 and Cu + /SiO 2 catalysts could be attributed to the radiative decay from the excited electronic state of the linear two-coordinate Cu + ions and planar three-coordinate Cu + ions, respectively. The addition of N 2 O onto the Cu + ion catalyst leads to the quenching of the photoluminescence of Cu + , indicating that N 2 O interacts with the photoexcited Cu + ion. UV irradiation of the catalysts in the presence of N 2 O led to the formation of N 2 and O 2 at 298 K, indicating that the photocatalytic decomposition of N 2 O proceeds on the Cu + ion catalysts. The reaction was found to proceed more efficiently on the Cu + /(SiO 2 ‚Al 2 O 3 ) catalyst than on the Cu + /Al 2 O 3 or Cu + /SiO 2 catalysts, suggesting that the two-coordinate Cu + species show higher activity for this reaction than the three-coordinate Cu + species.

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