open access

https://hdl.handle.net/2115/87236

Structural Characterization of Nickel-Doped Aluminum Oxide Cations by Cryogenic Ion Trap Vibrational Spectroscopy

英語

2021-11-04

American Chemical Society

Journal of physical chemistry A

125(43)

9527-9535

Isolated nickel-doped aluminum oxide cations (NiOm) (Al2O3)(n) (AlO)(+) with m = 1 -2 and n = 1-3 are investigated by infrared photodissociation (IRPD) spectroscopy in combination with density functional theory and the single-component artificial force-induced reaction method. IRPD spectra of the corresponding He-tagged cations are reported in the 400-1200 cm(-1) spectral range and assigned based on a comparison to calculated harmonic IR spectra of low-energy isomers. Simulated spectra of the lowest energy structures generally match the experimental spectra, but multiple isomers may contribute to the spectra of the m = 2 series. The identified structures of the oxides (m = 1) correspond to inserting a Ni-O moiety into an Al-O bond of the corresponding (Al2O3)(1-3)(AlO)(+) cluster, yielding either a doubly or triply coordinated Ni2+ center. The m = 2 clusters prefer similar structures in which the additional O atom either is incorporated into a peroxide unit, leaving the oxidation state of the Ni2+ atom unchanged, or forms a biradical comprising a terminal oxygen radical anion Al-O-center dot(-) and a Ni3+ species. These clusters represent model systems for under-coordinated Ni sites in alumina-supported Ni catalysts and should prove helpful in disentangling the mechanism of selective oxidative dehydrogenation of alkanes by Ni-doped catalysts.

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Accepted Manuscript

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of physical chemistry A, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/articlesonrequest/AOR-3WS6QQZYZGHSZVJJVJDV.

1089-5639