Spectral Study of the Inverse Effect of Metal on the Properties of a Carrier
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ICAL CHEMISTRY OF SURFACE PHENOMENA
Spectral Study of the Inverse Effect of Metal on the Properties of a Carrier L. M. Kustova,b,*, E. A. Redinaa, O. P. Tkachenkoa, A. L. Kustova,b, and V. B. Kazanskya aZelinsky
Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, 119991 Russia of Chemistry, Moscow State University, Moscow, 119991 Russia *e-mail: [email protected]
bDepartment
Received April 27, 2020; revised April 27, 2020; accepted April 29, 2020
Abstract—The effects of the mutual influence of supported metal nanoparticles and a carrier are considered for different cases where the carrier is a solid acid, a solid base, a semiconductor, or a conducting material. Special attention is given to the inverse side of this mutual influence, i.e., modification of the properties of the carrier itself due to the influence of metal particles, which has virtually not been studied or considered before. Keywords: metal–carrier interaction, acid–base carriers, IR spectroscopy of adsorbed CO, semiconductor carriers, nanoparticles, charge transfer, X-ray photoelectron spectroscopy DOI: 10.1134/S0036024420110187
INTRODUCTION Metallic nanoparticles deposited on porous carriers are a subject of constant interest in connection with their various practical applications. Such materials are used especially widely in catalysis, where the properties of catalysts are largely determined by the structural, electronic, and other characteristics of deposited nanoparticles. The high catalytic activity of metal catalysts can be due to factors such as the morphology and size of metal nanoparticles, the interaction between a metal and a carrier, and the means of sample synthesis [1]. The carrier helps to stabilize small nanoparticles (sometimes with sizes of less than 1 nm) and largely determines the morphology of the deposited nanoparticles and their uniform distribution according to size. This is true even when the carrier is an inert material that does not interact with deposited metal particles, but due to its porous structure (especially in the case of micropores) it helps to stabilize very small particles as a result of topological (geometric) effects. The selection of optimum conditions for the synthesis of metal catalysts can lead to strong interaction of between a metal and a carrier, resulting in electron transfer from the former to the latter with the formation of a partial positive charge on the metal or transfer in the opposite direction, as a result of which the metal acquires a partial negative charge [2–4]. This is very interesting, since the properties of metal particles, including such catalytic properties as activity and selectivity, change as a result of charge transfer. For deposited gold particles, it is known that upon a
reduction in particle size, the metal–metal bond lengths are shortened and the density of d-electrons increases [5]. The relative number of metal atoms on the faces, edges, and vertices of a nanoparticle is uniquely determined by its size [6]. Charge transfer is reliably determined by physical
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