Publication type: Article in scientific journal
Type of review: Peer review (publication)
Title: Adsorption states of N2/H2 activated on Ru nanoparticles uncovered by modulation-excitation infrared spectroscopy and density functional theory calculations
Authors: Rivera Rocabado, David S.
Noguchi, Tomohiro G.
Hayashi, Shio
Maeda, Nobutaka
Yamauchi, Miho
Ishimoto, Takayoshi
et. al: No
DOI: 10.1021/acsnano.1c07825
Published in: ACS Nano
Volume(Issue): 15
Issue: 12
Pages: 20079
Pages to: 20086
Issue Date: 28-Dec-2021
Publisher / Ed. Institution: American Chemical Society
ISSN: 1936-0851
Language: English
Subjects: N2/H2 activation; N2/H2 adsorption state; Ru nanoparticle model; Ambient-condition infrared spectroscopy; Ammonia synthesis; Density functional theory; Modulation−excitation infrared spectroscopy
Subject (DDC): 660: Chemical engineering
Abstract: The adsorption states of N2 and H2 on MgO-supported Ru nanoparticles under conditions close to those of ammonia synthesis (AS; 1 atm, 250 °C) were uncovered by modulation-excitation infrared spectroscopy and density functional theory calculations using a nanoscale Ru particle model. The two most intense N2 adsorption peaks corresponded to the vertical chemisorption of N2 on the nanoparticle's top and bridge sites, while the remaining peaks were assigned to horizontally adsorbed N2 in view of the site heterogeneity of Ru nanoparticles. Long-term observations showed that vertically adsorbed N2 molecules gradually migrated from the top sites to the bridge sites. Compared to those adsorbed vertically, N2 molecules adsorbed horizontally exhibited a lower dipole moment, an increased N─N bond distance, and a decreased N─N bond order (i.e., were activated), which was ascribed to enhanced Ru-to-N charge transfer. H2 molecules were preferentially adsorbed horizontally on top sites and then rapidly dissociated to afford strongly surface-bound H atoms and thus block the active sites of Ru nanoparticles. Our results clarify the controversial adsorption/desorption behavior of N2 and H2 on AS catalysts and facilitate their further development.
Fulltext version: Published version
License (according to publishing contract): Licence according to publishing contract
Departement: School of Engineering
Organisational Unit: Institute of Materials and Process Engineering (IMPE)
Appears in collections:Publikationen School of Engineering

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