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16226 DOI: 10.1021/la101326c Langmuir 2010, 26(21), 1622616231Published on Web 07/01/2010 pubs.acs.org/Langmuir
 

Summary: 16226 DOI: 10.1021/la101326c Langmuir 2010, 26(21), 1622616231Published on Web 07/01/2010
pubs.acs.org/Langmuir
2010 American Chemical Society
Structure-Reactivity Correlations in Pd-Au Bimetallic Nanoclusters
Elad Gross and Micha Asscher*
Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
Received April 4, 2010. Revised Manuscript Received June 17, 2010
The effect of composition and morphology of bimetallic Pd-Au nanoclusters on their chemical reactivity has been
studied with acetylene decomposition and conversion to ethylene and benzene as the chemical probe. High resolution
transmission electron microscopy (HR-TEM) and CO-Temperature Programmed Desorption (TPD) measurements
were employed for structure and chemical composition determination. Pd-Au clusters were prepared in ultrahigh
vacuum (UHV) environment on SiO2/Si(100) by direct deposition (DD) to form 2D bimetallic nanostructures. Different
bimetallic cluster morphology could be obtained by employing the buffer layer assisted growth (BLAG) procedure with
amorphous solid water as buffer material. The BLAG bimetallic clusters were found to be more reactive than DD
particles toward acetylene hydrogenation to ethylene and trimerization to benzene. The morphology and composition of
DD clusters enabled the formation of both tilted (low adsorption energy) and flat laying (high adsorption energy)
benzene, while mainly tilted benzene was detected upon adsorption of acetylene on BLAG clusters. Moreover, the
reactivity of bimetallic clusters was compared to that of thin Pd film. Strong preference (100:1 ratio) toward acetylene
hydrogenation to ethylene over trimerization to benzene has been correlated with the lack of extended Pd(111) facets on
the bimetallic clusters that suppress the benzene formation.

  

Source: Asscher, Micha - Institute of Chemistry, Hebrew University of Jerusalem

 

Collections: Chemistry