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Cascade catalysis of highly active bimetallic Au/Pd nanoclusters: structure–function relationship investigation using anomalous small‐angle X‐ray scattering and UV–Vis spectroscopy
Author(s) -
Haas Sylvio,
Fenger Robert,
Fertitta Edoardo,
Rademann Klaus
Publication year - 2013
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889813018190
Subject(s) - nanoclusters , bimetallic strip , catalysis , nanoparticle , materials science , nanostructure , chemical physics , chemical engineering , small angle x ray scattering , colloid , spectroscopy , crystallography , nanotechnology , scattering , chemistry , physics , organic chemistry , quantum mechanics , engineering , optics
Recently, a so‐called `crown‐jewel' concept of preparation of Au/Pd‐based colloidal nanoclusters has been reported [Zhang, Watanabe, Okumura, Haruta & Toshima (2011). Nat. Mater. 11 , 49–52]. Here, a different way of preparing highly active Au/Pd‐based nanoclusters is presented. The origin of the increased activity of Au/Pd‐based colloidal bimetallic nanoclusters was unclear up to now. However, it is, in general, accepted that in the nanometre range (1–100 nm) the cluster size, shape and composition affect the structural characteristics ( e.g. lattice symmetry, unit cell), electronic properties ( e.g. band gap) and chemical properties ( e.g. catalytic activity) of a material. Hence, a detailed study of the relationship between the nanostructure of nanoclusters and their catalytic activity is presented here. The results indicate that a high surface‐to‐volume ratio of the nanoclusters combined with the presence of `both' Au and Pd isolated regions at the surface are crucial to achieve a high catalytic activity. A detailed structure elucidation directly leads to a mechanistic proposal, which indeed explains the higher catalytic activity of Au/Pd‐based catalysts compared with pure metallic Au or Pd. The mechanism is based on cascade catalysis induced by a single type of nanoparticle with an intermixed surface of Au and Pd.