Untitled

Zakharchenko, N. I.

doi:10.1023/a:1014861303777

Cited by 7 publications

(5 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Single crystalline Pt NPs are observed in some of the images even before annealing (Figure a−c). The lattice spacings measured after atomic oxygen exposure at RT [ d = 0.215(4), 0.232(4), 0.282(4) nm, Figure a,b,c], are in agreement with those previously reported for PtO x species, ,, namely, d (110) = 0.2137 nm in PtO, d (211) = 0.228 nm in Pt 3 O 4 , d (200) = 0.279 nm in Pt 3 O 4 , or d (100) = 0.266 nm in PtO 2 . , However, the lower values also fit metallic Pt. The identification of surface oxide phases on small NPs via TEM is very challenging due to several factors, including the possibility of having such phases present in a disordered structural form (amorphous), as well as possible artifacts intrinsic to the TEM technique that could result in local heating of the NPs and the decomposition of unstable surface oxides.…”

Section: Resultssupporting

confidence: 89%

Formation and Thermal Stability of Platinum Oxides on Size-Selected Platinum Nanoparticles: Support Effects

et al. 2010

View full text Add to dashboard Cite

This article presents a systematic study of the formation and thermal stability of Pt oxide species on sizeselected Pt nanoparticles (NPs) supported on SiO 2 , ZrO 2 , and TiO 2 thin films. The studies were carried out in ultrahigh vacuum (UHV) by temperature-dependent X-ray photoelectron spectroscopy (XPS) measurements and ex situ transmission electron microscopy and atomic force microscopy. The NPs were synthesized by inverse micelle encapsulation and oxidized in UHV at room temperature by an oxygen plasma treatment. For a given particle size distribution, the role played by the NP support on the stability of Pt oxides was analyzed. PtO 2 species are formed on all supports investigated after O 2 -plasma exposure. A two-step thermal decomposition (PtO 2 f PtO f Pt) is observed from 300 to 600 K upon annealing in UHV. The stability of oxidized Pt species was found to be enhanced on ZrO 2 under annealing treatments in O 2 . Strong NP/support interactions and the formation of Pt-Ti-O alloys are detected for Pt/TiO 2 upon annealing in UHV above 550 K but not under an identical treatment in O 2 . Furthermore, thermal treatments in both environments above 700 K lead to the encapsulation of Pt by TiO x . The final shape of the micellar Pt NPs is influenced by the type of underlying support as well as by the post-deposition treatment. Spherical Pt NPs are stable on SiO 2 , ZrO 2 , and TiO 2 after in situ ligand removal with atomic oxygen at RT. However, annealing in UHV at 1000 K leads to NP flattening on ZrO 2 and to the diffusion of Pt NPs into TiO 2 . The stronger the nature of the NP/support interaction, the more dramatic is the change in the NP shape (TiO 2 > ZrO 2 > SiO 2 ).

show abstract

Section: Resultssupporting

confidence: 89%

Formation and Thermal Stability of Platinum Oxides on Size-Selected Platinum Nanoparticles: Support Effects

et al. 2010

View full text Add to dashboard Cite

show abstract

“…Modern examples of applications comprise the catalytic hydrosilylation of functionalized alkenes 9 and aryl alkynes, 10 the oxidation of ethanol to acetic acid, 11 the oxidation of ammonia to nitrogen(II) oxide. 12 Finally, superficial oxide phases can form on platinum nanoparticles under oxidizing conditions (e. g. in automobile catalysts) and may trigger the oxidation of carbon compounds according to Mars-van-Krevelen reaction mechanisms. 13,14 In electrochemical applications involving platinum electrodes, the formation of a thin oxide film on the metal surface affects the mechanism and kinetics of various anodic processes (see Ref.…”

Section: Introductionmentioning

confidence: 99%

Density functional theory study of platinum oxides: From infinite crystals to nanoscopic particles

et al. 2007

View full text Add to dashboard Cite

For over a century, platinum oxides find technologically relevant applications in various fields ranging from catalysis to electrochemistry and nanoelectronics. We have performed a density functional theory study of the PtO, Pt3O4, and PtO2 bulk oxide phases. In our calculations, PtO and Pt3O4 present metallic character at the simple generalized gradient approximation level. The application of Hubbard corrections to the Kohn-Sham Hamiltonian opens a small gap in the electronic band structure of PtO, but not of Pt3O4, in which metallic Pt-Pt bonds are revealed by a Bader analysis of the calculated electronic structure. These results, together with the noninteger oxidation number of the Pt ions, are indicative of metallicity of the Pt3O4 phase which may be consistent with the known metallic character of platinum bronzes. Moreover, we have calculated the relative thermodynamic stabilities of platinum oxide Wulff's particles and discussed the results in the context of catalysis. Finally, we have predicted that the formation of alpha-PtO2 nanotubes could be energetically feasible. This result is of potential interest both for nanotechnological and catalytic applications and may explain the formation of curled alpha-PtO2 sheets observed in high-resolution transmission electron microscopy images

show abstract

“…A first example is the HCN synthesis by the Degussa process, in which a 1:1 mixture of methane and ammonia is passed through a Pt-coated tube-wall reactor, or by the related process using bimetallic gold-platinum cluster cations as catalyst [3]. The use of Pt 3 O 4 in the catalytic oxidation of ammonia to NO for the industrial production of nitric acid [4] has also been extensively studied. New hydrophobic fluorinated carbon supported Pt catalysts, promoting the reaction of nitrogen oxides NO x with NH 3 , are investigated in order to develop a very effective post combustion De-NO x technology for controlling NO x emissions [5].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterisation of the amidine complexes trans-[PtCl(NH3){HNC(NH2)R}2]Cl (R=Me, Ph, CH2Ph) derived from addition of NH3 to the coordinated nitriles in trans-[PtCl2(NCR)2]

Natile

Intini

Bertani

et al. 2005

Journal of Organometallic Chemistry

View full text Add to dashboard Cite

Untitled

Cited by 7 publications

References 2 publications

Formation and Thermal Stability of Platinum Oxides on Size-Selected Platinum Nanoparticles: Support Effects

Formation and Thermal Stability of Platinum Oxides on Size-Selected Platinum Nanoparticles: Support Effects

Density functional theory study of platinum oxides: From infinite crystals to nanoscopic particles

Synthesis and characterisation of the amidine complexes trans-[PtCl(NH3){HNC(NH2)R}2]Cl (R=Me, Ph, CH2Ph) derived from addition of NH3 to the coordinated nitriles in trans-[PtCl2(NCR)2]

Contact Info

Product

Resources

About