Remarkable Structural Effect on the Gold-Hydrogen Analogy in Hydrogen-Doped Gold Cluster
Meghaa,b, Kamal Chinnathambia,b, Krishnakanta Mondalc, Tapan K. Ghantyb,d, Arup Banerjeea,b
aHuman Resources Development Section, Raja Ramanna Centre for Advanced Technology, Indore 452013, India
bHomi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai 450094, India
cDepartment of Physics, Indian Institute of Science Education and Research, Pune 411008, India
dTheoretical Chemistry Section, Chemistry Group, Bhabha Atomic Research Centre, Mumbai 400085, India
Abstract
In accordance with the well established gold-hydrogen analogy a hydrogen atom possess properties similar to a gold atom in gold clusters. In a recent study it has been shown that the properties of a hydrogen atom doped Au7H cluster are not in conformity with the aforementioned analogy. We study the properties of Au7H cluster to re-examine the validity of gold-hydrogen analogy in the context of adsorption of CO and O2molecules on pristine Au8and hydrogen-atom doped Au7H gold clusters. For this purpose, we useab initiodensity functional theory based method with generalized gradient approximation (GGA) and Meta-GGA exchange-correlation functionals. We find that the lowest energy structure of both Au7H and Au8 clusters is planar with symmetries C2vand D4h, respectively. The adsorption energies of CO and O2molecules on the most stable planar isomer of Au7H are almost the same as those on the parent Au8cluster with D4hsymmetry proving the validity of gold-hydrogen analogy. On the other hand, for the high energy three-dimensional isomer of Au7H cluster obtained from pristine Au8cluster with Tdsymmetry, we find an appreciable enhancement in adsorption energy of CO and O2molecules in comparison to that for the corresponding bare Au8cluster. The high reactivity of the 3D isomer of Au7H cluster may be because of its existence in a higher energy state than its most stable planar isomer. Our study reveals that the gold-hydrogen analogy is obeyed by the most stable planar isomer of Au7H cluster and the higher energy isomers may fail to satisfy the analogy.