Persona: Fernández Sánchez, Eva María
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Fernández Sánchez
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Eva María
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Publicación Sequential adsorption of multiple CO molecules on Au10-and Au9Zn-triangular clusters: The crucial role of a single atomic impurity(Royal Society of Chemistry, 2025-02-05) Fernández Sánchez, Eva María; Balbás, Luis C.In this paper, we find, using DFT calculations, that the patterns of sequential adsorption sites of up to six CO molecules on the planar Au10− and Au9Zn− clusters differ radically. Thus, CO prefers bridge (top) adsorption sites forming Au10(CO)n− compounds with n = 1–3 (n = 4–5), but top (bridge) sites occur for Au9Zn(CO)n− compounds when n = 1–4 (n = 5–6). These facts are distinguishable in the CO stretching spectra of both types of compounds. Severe distortions and broken Au–Au bonds appear in the morphology of pure compounds after CO adsorption, but only small distortions are seen in the doped compounds. Using the nudged elastic band (NEB) method, we find the reaction paths of CO adsorption for pure n = 3 and doped n = 5 compounds. The estimated reaction barrier of the pure compound is much higher than that of the doped one. We also find important differences in the electronic properties of these compounds as functions of the size n: adsorption energy, bond lengths, angles, Bader atomic charges, and HOMO–LUMO gaps. We argue that all these differences are due to a larger charge reorganization in the doped than in the pure gold compounds, because of the Zn atom's lower electronegativity than that of gold and carbon. Comparison with previous results for multiple adsorption of NO molecules sheds light on the characteristics of Au–CO and Au–NO bonds.Publicación Adsorption of multiple NO molecules on Au10− and Au9Zn− planar clusters. A comparative DFT study(Royal Society of Chemistry, 2023-06-01) Fernández Sánchez, Eva María; Balbás, Luis C.The doping of atomic clusters with transition-metal atoms modifies to a lesser or greater extent the catalytic properties of the pure forms. Here we study by means of density functional theory (DFT) the adsorption of up to six NO molecules on Au10− and Au9Zn− clusters, both with well-tested D3h planar geometry, to learn how precise modifications of the atomic and electronic environment, namely one atom and a valence electron, affect the bonding of multiple NO molecules to anionic gold clusters. First, we confirm that these clusters have D3h symmetry as determined by L. S. Wang and coworkers using photoelectron spectroscopy experiments [Kulichenko et al., J. Phys. Chem. A, 2021, 125, 4606]. Second, we verify that Au10(NO)n− with n ≤ 6 does not form adsorbed (NO)2 dimers, as realized by the experiments of Ma and coworkers [Ma et al., Phys. Chem. Chem. Phys., 2020, 22, 25227] using a mini flow-tube reactor at 150 K. Third, we discover that the ground state of the doped Au9Zn(NO)6− compound forms a (NO)2cis-dimer bridging two non-corner Au atoms of the Au9Zn(NO)4− compound. The discussion of adsorption energies, spin multiplicities, bond lengths, charge trends, vibrational strength frequencies of adsorbed NO's, and projected density of states (PDOS), brings additional testable differences between Au10(NO)n− and Au9Zn(NO)n− compounds (n ≤ 6).