The Adsorption of Hydrogen on Au n Ni m and Au n Cu m Clusters ( n + m = 13): Quantum-Chemical Simulation
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CTURE OF CHEMICAL COMPOUNDS, QUANTUM CHEMISTRY, SPECTROSCOPY
The Adsorption of Hydrogen on AunNim and AunCum Clusters (n + m = 13): Quantum-Chemical Simulation N. V. Dokhlikovaa, *, A. K. Gatina, S. Yu. Sarvadiia, E. I. Rudenkoa, M. V. Grishina, and B. R. Shuba aSemenov
Federal Research Center for Chemical Physics, Russian Academy of Sciences, Moscow, Russia *e-mail: [email protected] Received May 22, 2019; revised September 25, 2019; accepted October 21, 2019
Abstract—The adsorption of hydrogen on bimetallic gold–nickel and gold–copper nanoparticles is simulated quantum chemically. We find that the changes in the adsorption properties of the bimetallic nanosystem are due to the change in distances between atoms and the redistribution of the electron density in the cluster. This leads to an increase in the bond energy of the hydrogen atom near the Ni/Cu atoms; and a decrease, near the Au atoms of the bimetal cluster. Keywords: nanoparticles, gold, nickel, hydrogen, adsorption, interaction, quantum-chemical simulation, scanning tunneling microscopy and spectroscopy DOI: 10.1134/S1990793120050036
INTRODUCTION Currently, the bimetallic nanoparticles are widely used in nanocatalysis due to their unique physicochemical properties: selectivity [1], reactivity [2], and stability [3]. The strong change in the properties of bimetallic nanosystems in comparison with those of monometallic systems with the same elemental composition, however, is attracting the greatest attention. This effect is due to the interaction between different atoms of a bimetal and due to the deformation of the geometric structure due to different lattice constants of crystals of the initial substances [4]. The combined action of these factors can lead to a nonlinear change in the parameters of a bimetallic system, i.e., to a synergistic effect. The mutual influence of different atoms on each other and on the processes in real bimetallic nanoparticles (for example, gas adsorption) can be confused because of a large number of variable parameters, which complicates the description and study of such nanosystems [5]. The numerical experiments, however, make it possible to accurately control the changes in the atomic and electronic structures of bimetallic nanoparticles for a better understanding of catalytic reactions with their participation. In this study, the nanoparticles consisting of gold– nickel and gold–copper atoms are numerically simulated. The published data indicate that the change in the elemental composition of gold nanostructures with transition or noble metal atoms as additives can lead to a strong change in the adsorption and catalytic properties of the resulting bimetallic nanosystem. Indeed, the authors found that doping gold clusters (AuN, N = 2–7) with atoms of transition metals of the
platinum group (Ni, Pt, and Pd) increases the stability of the bimetal cluster [6]. In this case, its adsorption and electronic properties are due to the interaction between external electron orbitals of gold and impurity atoms, i.e., the degre
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