Stability of nanostructured silver-platinum alloys

Abstract

The stability of Ag-Pt systems: 13-atoms icosahedral cluster model (Ag13-nPtn) and 54-atoms (111) surface slab model (45Ag9Pt) have been systematically investigated by using Density Functional Theory within the generalized gradient approximation (DFT-GGA). Experimentally tested resistance of AgPt alloy nanoparticles supported on silica to decay upon temperature treatment (423 K-573 K in N2 flow) have shown to correlate with theoretical results. The stability of the clusters as a function of AgPt composition decreases with increasing content of Pt. The general stability trend of the AgPt alloy was maintained, in theory and experiment, for the Ag/Pt molar ratio of 1.6-5.1. Two particularly stable Ag/Pt compositions were revealed: 1.6 and 0.4. It was also found that surface location of platinum is responsible for stabilization of the Ag-Pt nanostructured alloy.

Au-Ag/TiO2 Thin Films Preparation by Laser Ablation and Sputtering Plasmas for Its Potential Use as Photoanodes in Electrochemical Advanced Oxidation Processes (EAOP)

“…For the samples Au/TiO2 and Ag/TiO2, the presence of absorbance bands peaking at 557 nm and 441 nm is clearly observed, attributed to the surface resonance plasmons of Au and Ag, and indicating the presence of nanoparticles with spherical shapes and sizes in the nanometer scale; ranging 15-20 nm for Ag and 20-30 nm for Au. The spectrum corresponding to the sample with Au-Ag does not show defined absorbance band peaks, probably due to the lack of spherical nanoparticle formation [11,33,43,44].…”

“…The observed sizes are in good agreement with the wavelength position of the surface plasmons discussed in the UV-Vis results (Figure 6a). Therefore, it can be inferred that the thermal process did not modify the metallic particles deposited by ablation over the thin films [32,43,44].…”

“…Therefore, it can be inferred that the thermal process did not modify the metallic particles deposited by ablation over the thin films. [32,43,44]. Figure 6b shows the transmittance spectra of the thin films.…”

Formation of Catalytically Active Nanoparticles under Thermolysis of Silver Chloroplatinate(II) and Chloroplatinate(IV)

“…The stability of the synthesised nanoalloys is also a significant aspect. As shown in [27], the stability of Ag/Pt clusters decreases with increasing Pt content depending on the cluster composition. The nanoalloy stability increases in the following sequence: 5.1 < 3.6 < 2.5 < 1.6 of the Ag/Pt molar ratio.…”

A platinum promoted Ag/SBA-15 catalyst effective in selective oxidation of methanol – design and surface characterization

“…These Ag/Pt molar ratios are much higher than those required for the formation of Ag-Pt alloy nanoparticles. 20 In the one-pot modi-cation the initial solution contained 20 times lower amount of platinum ions than silver. It is possible that much higher amount of Ag + ions interacting with thiol groups (SH from MPTMSfunctionalization agent) limited the access of PtCl 6 À to anchoring sites.…”