title: Zinc-Containing Magnetic Oxides Stabilized by a Polymer: One Phase or Two?
abstract: Here we developed a new family of Zn-containing magnetic oxides of different structures by thermal decomposition of Zn(acac)2 in the reaction solution of preformed magnetite nanoparticles (NPs) stabilized by polyphenylquinoxaline. Upon an increase of the Zn(acac)2 loading from 0.15 to 0.40 mmol (vs 1 mmol of Fe(acac)3), the Zn content increases, and the Zn-containing magnetic oxide NPs preserve a spinel structure of magnetite and an initial, predominantly multicore NP morphology. X-ray photoelectron spectroscopy (XPS) of these samples revealed that the surface of iron oxide NPs is enriched with Zn, although Zn species were also found deep under the iron oxide NP surface. For all the samples, XPS also demonstrates the atom ratio of Fe(3+)/Fe(2+) = 2:1, perfectly matching Fe3O4, but not ZnFe2O4, where Fe(2+) ions are replaced with Zn(2+). The combination of XPS with other physicochemical methods allowed us to propose that ZnO forms an ultrathin amorphous layer on the surface of iron oxide NPs and also diffuses inside the magnetite crystals. At higher Zn(acac)2 loading, cubic ZnO nanocrystals coexist with magnetite NPs, indicating a homogeneous nucleation of the former. The catalytic testing in syngas conversion to methanol demonstrated outstanding catalytic properties of Zn-containing magnetic oxides, whose activities are dependent on the Zn loading. Repeat experiments carried out with the best catalyst after magnetic separation showed remarkable catalyst stability even after five consecutive catalytic runs.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Baird
authors.forename: Yaroslav
authors.initials: Y
authors.lastname: Losovyj
authors.affiliation: A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences , 28 Vavilov Street, Moscow 119991, Russia.
authors.forename: Ekaterina Yu
authors.initials: EY
authors.lastname: Yuzik-Klimova
authors.affiliation: A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences , 28 Vavilov Street, Moscow 119991, Russia.
authors.forename: Nina V
authors.initials: NV
authors.lastname: Kuchkina
authors.affiliation: A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences , 28 Vavilov Street, Moscow 119991, Russia.
authors.forename: Zinaida B
authors.initials: ZB
authors.lastname: Shifrina
authors.forename: Maren
authors.initials: M
authors.lastname: Pink
authors.forename: Barry D
authors.initials: BD
authors.lastname: Stein
authors.forename: David Gene
authors.initials: DG
authors.lastname: Morgan
authors.forename: Tianhao
authors.initials: T
authors.lastname: Wang
authors.affiliation: Department of Biotechnology and Chemistry, Tver State Technical University , 22 A Nikitina Street, 170026 Tver, Russia.
authors.forename: Mikhail A
authors.initials: MA
authors.lastname: Rubin
authors.affiliation: Department of Biotechnology and Chemistry, Tver State Technical University , 22 A Nikitina Street, 170026 Tver, Russia.
authors.forename: Alexander I
authors.initials: AI
authors.lastname: Sidorov
authors.affiliation: Department of Biotechnology and Chemistry, Tver State Technical University , 22 A Nikitina Street, 170026 Tver, Russia.
authors.forename: Esther M
authors.initials: EM
authors.lastname: Sulman
authors.affiliation: A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences , 28 Vavilov Street, Moscow 119991, Russia.|Faculty of Science, Department of Physics, King Abdulaziz University , Jeddah 21589, Saudi Arabia.
authors.forename: Lyudmila M
authors.initials: LM
authors.lastname: Bronstein
keywords: X-ray photoelectron spectroscopy; magnetite; nanoparticles; polymer; zinc oxide