Trends and Properties of 13-Atom Ag–Au Nanoalloys I: Structure and Electronic Properties

Barron, Hector; Fernández-Seivane, Lucas; Weissker, Hans‐Christian; López-Lozano, Xóchitl

doi:10.1021/jp403230t

Cited by 20 publications

(17 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Barron indicate that the Kohn−Sham gap value of about 0.2 eV is a general feature of the 13-atom Ag−Au clusters. 17 The most stable structure has a total spin of 1 μ B , which is determined by Mulliken population analysis.…”

Section: Resultsmentioning

confidence: 99%

Ag₇Au₆ Cluster as a Potential Gas Sensor for CO, HCN, and NO Detection

Yong

et al. 2015

J. Phys. Chem. C

View full text Add to dashboard Cite

Ag−Au bimetallic clusters have demonstrated extreme sensitivity, which can be theoretically explained by the conductivity change of the clusters induced by the absorption process, to molecules such as CO, H 2 S, and so forth. Recently, a 13-atom alloy quantum cluster (Ag 7 Au 6 ) has been experimentally synthesized and characterized. Here, the adsorption of CO, HCN, and NO on the Ag 7 Au 6 cluster was investigated using density functional theory calculations in terms of geometric, energetic, and electronic properties to exploit its potential applications as gas sensors. It is found that the CO, HCN, and NO molecules can be chemisorbed on the Ag 7 Au 6 cluster with exothermic adsorption energy (−0.474 ∼ −1.039 eV) and can lead to finite charge transfer. The electronic properties of the Ag 7 Au 6 cluster present dramatic changes after the adsorption of the CO, HCN, and NO molecules, especially its electric conductivity. Thus, the Ag 7 Au 6 cluster is expected to be a promising gas sensor for CO, HCN, and NO detection. ■ INTRODUCTIONThe environmental gas monitoring and controlling is now recognized as an important issue for our safety and health. Much research has been focused on the development of suitable gas-sensitive materials for continuous monitoring and setting off alarms for hazardous chemical vapors present beyond specified levels. 1−4 Chemical gases such as CO, HCN, and NO are highly toxic to human beings and animals as they inhibit the consumption of oxygen by body tissues. They are colorless, odorless, and tasteless, and thus human beings do not have timely alertness to their presence. For example, exposure levels of 100 ppm of HCN which would result in death are about 1 h or less in some cases, while exposure levels of 500 ppm of HCN are within 15 min. 5 Higher concentration levels will result in faster onset of symptoms or death. Therefore, effective methods for sensing these three toxic gases are highly desired.Bimetallic nanoclusters (also called "nanoalloys" 6 ) are of great interest from both the fundamental and the technological points of view not only because of their new degrees of freedom for understanding their electronic and geometric properties of clusters but also because of their potential applications in catalysis, 7−11 optics, 12−14 nanoelectronics, 15 and sensing. 16 In particular, silver−gold (Ag−Au) clusters have been investigated extensively from a computational point of view 17−27 as well as experimentally. 28−37 Their unique physicochemical properties depend on the shape and structure of the clusters, the surface segregation of the clusters, and the alloying extent or atomic distribution in nanoclusters. Recently, Ag−Au clusters are investigated as potential catalysts or sensors for removal and detection of toxic molecules. In this regard, adsorption of toxic molecules on Ag−Au clusters has attracted several theoretical and experimental studies. 38−45 Experimental investigations on CO adsorption on Au n Ag m (n = 10−45, m = 0, 1, 2) clusters at 140 K indicate that the CO molecule a...

show abstract

Section: Resultsmentioning

confidence: 99%

Ag₇Au₆ Cluster as a Potential Gas Sensor for CO, HCN, and NO Detection

Yong

et al. 2015

J. Phys. Chem. C

View full text Add to dashboard Cite

show abstract

“…8 AuAg NPs is probably one of the most studied bimetallic systems. [9][10][11][12] This is partially because the surface plasmon absorptions of Ag and Au NPs are distinctive and generally restricted to around 400 nm and 520 nm, respectively, while that resulting from mixing Ag and Au into a bimetallic nanoparticle can be tuned between 400 nm and 520 nm, depending on the particle composition, size and morphology. [13][14] In the bulk phase, Ag and Au form alloys for all compositions with very little surface segregation due to their similar lattice constants, namely 4.09 Å for Ag and 4.08 Å for Au.…”

Section: Introductionmentioning

confidence: 99%

Impact of the AuAg NPs Composition on Their Structure and Properties: A Theoretical and Experimental Investigation

et al. 2014

View full text Add to dashboard Cite

Bimetallic AuAg NPs (NPs) were synthesized via chemical reduction of AuCl 3 and AgNO 3 and fully characterized by several experimental techniques and theoretical calculations. The plasmon absorptions of these NPs were correlated with the most stable particle structure through different simulations, revealing the most stable structure to be consisted of a gold core and a silver shell. This structural motif was then confirmed by HR-TEM coupled with line-scan EDS and molecular dynamics. Finally, the impact of the nanoparticle composition on their catalytic performance for glycerol electro-oxidation was evaluated. The better catalytic performance in terms of the onset potential found for the Au 50 Ag 50 and Au 75 Ag 25 catalysts suggests the existence of a synergistic effect between Au and Ag.

show abstract

“…It should be noted that the icosahedron, while energetically more stable than the helical cluster, is not the global minimum for Ag 13 . For the neutral cluster, the icosahedron is highly spinpolarized and uncompetitive with the buckled biplanar motif, 46,47 and is therefore unlikely to be the global minimum for Ag 13 + .…”

Section: Cluster Geometriesmentioning

confidence: 99%

A theoretical study of the structures and optical spectra of helical copper–silver clusters

Heard

Johnston

2014

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

The structures and optical response of helical clusters ("Bernal spirals") with compositions Ag12Cu1(+) and Ag1Cu12(+) are calculated within Kohn-Sham density functional theory and the configuration interaction singles variant of time dependent density functional theory. The effects of dopant position within the cluster on the vertical excitation spectrum are investigated according to the underlying electronic structure of the major transitions. The roles of symmetry and geometry are investigated by calculating the optical response of helical, icosahedral and nanorod-like clusters of Ag13(+), finding local structure to be significant in driving the resultant optical response at the subnanometre scale. Further, it is noted that helical clusters have optical properties which are quite distinct from those of nanorods of similar dimensions. The effect of multiple doping is studied by introducing copper atoms into the centre of the silver helix, over the composition range Ag13(+) to Ag6Cu7(+). There is a complex variation of the major plasmon-like peak over this range, attributed to subtle variations in the influence of the copper 3d band on the excitations and charge transfer for different sites within the cluster. This work suggests that coinage metal nanohelices have unusual, tunable electronic properties, which in addition to their inherent chirality makes them interesting systems to study for chiral catalysis and optoelectronics.

show abstract

Trends and Properties of 13-Atom Ag–Au Nanoalloys I: Structure and Electronic Properties

Cited by 20 publications

References 48 publications

Ag₇Au₆ Cluster as a Potential Gas Sensor for CO, HCN, and NO Detection

Ag₇Au₆ Cluster as a Potential Gas Sensor for CO, HCN, and NO Detection

Impact of the AuAg NPs Composition on Their Structure and Properties: A Theoretical and Experimental Investigation

A theoretical study of the structures and optical spectra of helical copper–silver clusters

Contact Info

Product

Resources

About

Trends and Properties of 13-Atom Ag–Au Nanoalloys I: Structure and Electronic Properties

Cited by 20 publications

References 48 publications

Ag7Au6 Cluster as a Potential Gas Sensor for CO, HCN, and NO Detection

Ag7Au6 Cluster as a Potential Gas Sensor for CO, HCN, and NO Detection

Impact of the AuAg NPs Composition on Their Structure and Properties: A Theoretical and Experimental Investigation

A theoretical study of the structures and optical spectra of helical copper–silver clusters

Contact Info

Product

Resources

About

Ag₇Au₆ Cluster as a Potential Gas Sensor for CO, HCN, and NO Detection

Ag₇Au₆ Cluster as a Potential Gas Sensor for CO, HCN, and NO Detection