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 prepar ed and analyzed spectroscopically. Data from luminescence and Raman spectro scopies along with extended Huckel calculations indicate the formation of [ M(CN)(2)(-)](n) oligomers (M = Ag, Au) in the zeolite host. Variations in l uminescent properties as a function of excitation wavelength, dopant concen tration inside the zeolite host, and temperature facilitate assignment of c luster 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 photode composition of carbaryl in aqueous solution. The photodecomposition of carb aryl at room temperature shows different decomposition products in the pres ence 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 phot odecomposition rates with carbaryl that are 40 and 60 times faster, respect ively, than for carbaryl alone in aqueous solution.