Photoluminescence and Raman spectroscopy as probes to investigate silver and gold dicyanide clusters doped in A-zeolite and their photoassisted degradation of carbaryl

Dicyanoaurate and dicyanoargentate ions doped in A-type zeolite were prepared and analyzed spectroscopically. Data from luminescence and Raman spectroscopies along with extended Huckel calculations indicate the formation of [M(CN)(2)(-)](n) oligomers (M = Ag, Au) in the zeolite host. Variations in luminescent properties as a function of excitation wavelength, dopant concentration inside the zeolite host, and temperature facilitate assignment of cluster structures. The data obtained from a comparison of Ag- and Au-doped silica and gamma -alumina. show that the [M(CN)(2)(-)](n) clusters form in the channels of the zeolite rather than on the surface. The [M(CN)(2)(-)](n) clusters in A zeolite show strong catalytic activities toward the photodecomposition of carbaryl in aqueous solution. The photodecomposition of carbaryl at room temperature shows different decomposition products in the presence and absence of the M(CN)2- doped A zeolite catalyst. In addition, the decomposition rate constants increase as the metal content increases. The M(CN)2- doped in A zeolite samples with M = 24.2Ag% and 42.3Au% produce photodecomposition rates with carbaryl that are 40 and 60 times faster, respectively, than for carbaryl alone in aqueous solution.