2022-05-27T07:29:49Zhttps://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/187652021-06-14T09:01:48Zcom_10261_14181com_10261_4col_10261_14182
http://hdl.handle.net/10261/18765
10.1039/b910200k
18557
Mechanism of molecular hydrogen dissociation on gold chains and clusters as model prototypes of nanostructures
Royal Society of Chemistry (UK)
2009
Zanchet, Alexandre
Dorta-Urra, A.
Roncero, Octavio
rp14174
Flores, F.
Tablero, César
Paniagua, Miguel
Aguado, Alfredo
2009
The reactivity of H2 on several gold clusters is studied using density functional theory with
generalized gradient approximation methods, as model systems designed to study the main effects
determining their catalytic properties under controlled conditions. Border effects are studied in
finite linear gold chains of increasing size and compared with the corresponding periodic systems.
In these linear chains, the reaction can proceed with no barrier along the minimum energy
path, presenting a deep chemisorption well of E1.4 eV. The mechanism presents an
important dependence on the initial attacking site of the chain. Linear Au4 chains joined to
model-nanocontacts, formed by 2 or 3 gold atoms, in a planar triangle or in a pyramid,
respectively, are also studied. The reaction barriers found in these two cases are E0.24 and
0.16 eV, respectively, corresponding to H2 attacking the more coordinated edge atom of the linear
chain. The study is extended to planar clusters with coordinations IV and VI, for which higher H2
dissociation barriers are found. However, when the planar gold clusters are folded, and the
Au–Au distances elongated, the reactivity increases considerably. This is not due to a change of
coordination, but to a larger flexibility of the gold orbitals to form bonds with hydrogen atoms,
when the planar sd-hybridization is broken. Finally, it is concluded that the major factor
determining the reactivity of gold clusters is not strictly the coordination of gold atoms but their
binding structure and some border effects.
closedAccess
Physical Chemistry Chemical Physics 11: 10122–10131(2009)