Silver Clusters and Chemistry in Zeolites

DNA-stabilized, fluorescent, metal nanoclusters for biosensor development

“…Before the seminal work in 2002 by Zheng and Dickson who used dendrimers as a stabilizer [12], metal NCs were only prepared in cryogenic noble gases or in solid zeolites [30][31][32]. Following this initial discovery, the Dickson group further showed that cytosine (C)-rich DNA can also stabilize fluorescent AgNCs [15], which represents the first connection between metal NCs and DNA.…”

Influence of alternative cations distribution in AgxLi96-x-LSX on dehydration kinetics and its selective adsorption performance for N2 and O2

“…During the N 2 and O 2 isotherm measurements at 273 and 298 K, the Ag x Li 96-x -LSX samples were turned to yellow-deep brown color from gray color after dehydration, indicating the formation of silver clusters, which is found in good agreement with the literature. 8 As can be seen in Figs. 4A(b) and 4B(b), after 3.87 wt % of Ag + was exchanged in Ag 3.87 Li 88.82 Na 3.31 -LSX, the N 2 adsorption as well as N 2 /O 2 separation factor (5.41 and 5.78) were increased as compared to the parent Li 95.95 Na 0.05 -LSX (Figs.…”

“…Thus, it can be stated that the mechanism function belongs to the mechanism of Nucleation and growth (N and G) and is the most probable describing function for the dehydration step. Concerning the second peak of decomposition (chemisorbed water), the R 2 was obtained again with mechanism 8.77 Na 1.61 -LSX, the first peak of thermal decomposition (physisorbed water) is characterized by mechanism function no. 16, which was assumed to have integral form g(α)= − ln(1 − α) belongs to the Mampel (first order) model related to nucleation and growth mechanism, whereas the second and third peaks of Ag 32.54 Li 71.6 Na 2.53 -LSX are characterized by function no.…”

“…Earlier in 1964, Habgood 7 found that silver has very strong influence on the adsorption characteristics of bi-metallic zeolites due to its stronger polarizing force than other alkali and alkaline earth cations. Sun and Seff 8 further demonstrated that Ag + can be exchanged completely into zeolites, and its reversible oxidation-reduction properties provide an excellent model system not only for studying the mechanism of formation of noble metal clusters in zeolite channels and cavities but also the catalytic mechanism of hydrocarbons for the dehydrogenation. Since the good N 2 /O 2 selectivity and higher N 2 adsorption capacity of bi-metallic Li x Al y -X zeolite have been reported, the Li x Na 96-x -LSX and Ag x Li 96-x -LSX have become the best sorbents for use in air separation via PSA or VSA processes.…”

Nanostructured Ag-zeolite Composites as Luminescence-based Humidity Sensors

“…3,4 The latter properties confer to silver-zeolite composites the ability to optically respond to external stimuli, such as variations of moisture within the zeolite scaffold [6][7][8] or the presence of determined gases; therefore their use as water vapor and gas sensors has been suggested. 9,10 In a recent study we have demonstrated that the optical response of Ag-zeolites to moisture is not only correlated to changes in the absorption or quenching of their emission but also to the appearance of different emission colors with respect to their water content. 5 The stabilization of silver clusters in partially Li exchanged LTA zeolites led to the formation of a moisture-responsive material in which changes in the relative low humidity scale were reflected in a dynamic color change from a blue to green/yellow emission in dehydrated and hydrated samples, respectively.…”