In-situ electrochemical atomic force microscopy study of aging of magnetron sputtered Pt-Co nanoalloy thin films during accelerated degradation test

Abstract A Pt-Co nanoalloy thin film catalyst was prepared by using simultaneous magnetron sputtering of Pt and Co. The catalyst was characterized during accelerated degradation test using in-situ electrochemical atomic force microscopy complemented with ex-situ techniques such as energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and synchrotron radiation photoelectron spectroscopy. The combined results gave the full step-by-step picture of the catalyst behavior during the aging test.

Electronic exchanges between adsorbed Ni atoms and TiO2(110) surface evidenced by resonant photoemission

Abstract Nickel was deposited on stoichiometric TiO2(1 1 0) surface in the 0.02–2.1 equivalent monolayer (eqML) range and analyzed by means of photoemission and resonant photoemission. In the case of very low coverage (lower than 0.1 eqML), deposited nickel reacts with the surface through an electronic transfer from nickel atoms towards titanium ions. This exchange caused the filling of unoccupied Ti3d states leading to the increase of a peak in the TiO2 band gap. These states can be better characterized through resonant photoemission experiments at the Ti 3p → 3d absorption edge: for very low coverage, these states in the TiO2 band gap have resonant behavior of Ti3d electrons rather than N…

Maximum Noble-Metal Efficiency in Catalytic Materials: Atomically Dispersed Surface Platinum

International audience; Platinum is the most versatile element in catalysis, but it is rare and its high price limits large-scale applications, for example in fuel-cell technology. Still, conventional catalysts use only a small fraction of the Pt content, that is, those atoms located at the catalyst's surface. To maximize the noble-metal efficiency, the precious metal should be atomically dispersed and exclusively located within the outermost surface layer of the material. Such atomically dispersed Pt surface species can indeed be prepared with exceptionally high stability. Using DFT calculations we identify a specific structural element, a ceria ``nanopocket'', which binds Pt2+ so strongly…

Back Cover: Maximum Noble-Metal Efficiency in Catalytic Materials: Atomically Dispersed Surface Platinum (Angew. Chem. Int. Ed. 39/2014)

Noble metal nanoparticles in organic matrix

Abstract The purpose of this work is the synthesis and study of the properties of nanocomposite structures created by noble metal (silver) nanoparticles (NP's), an exciting class of materials with unique properties differ from both bulk and atomic behavior, which are self-organize in a thin organic film of copper phthalocyanine (CuPc). The structure and morphology of this material, depending on the amount of deposited silver, was studied in ultrahigh vacuum using transmission electron microscopy (TEM) and photoelectron spectroscopy (PES). Metallic atoms deposited on the surface of an organic substrate diffuse into the substrate, forming NPs with a narrow size distribution, which correlates …

Rücktitelbild: Auf dem Weg zu größtmöglicher Effizienz bei der katalytischen Nutzung von Edelmetallen: atomar dispergiertes Oberflächen-Platin (Angew. Chem. 39/2014)

Auf dem Weg zu größtmöglicher Effizienz bei der katalytischen Nutzung von Edelmetallen: atomar dispergiertes Oberflächen-Platin

Platin ist das am vielseitigsten eingesetzte Element in der Katalyse. Allerdings begrenzt der hohe Preis des Edelmetalls die Verwendung in vielen Bereichen, z. B. in Katalysatormaterialien fur Brennstoffzellen. Trotzdem nutzen konventionelle Katalysatoren oftmals nur einen Bruchteil ihres Pt-Gehaltes, namlich diejenigen Atome, die sich auf der Oberflache des Katalysators befinden. Eine effizientere Edelmetallnutzung setzt somit eine hohere, bevorzugt atomare Dispersion der Pt-Atome auf der Oberflache voraus. Tatsachlich ist es moglich, solche atomar dispergierten Pt-Spezies mit sehr hoher Stabilitat auf einer Katalysatoroberflache herzustellen. Mithilfe von DFT-Rechnungen identifizieren wir…