Structural and chemical properties of NiOx thin films: the role of oxygen vacancies in NiOOH formation in a H2O atmosphere

Description: NiOx films grown from 50 nm thick Ni on Si(111) were put in contact with oxygen and subsequently water vapor at elevated temperatures. Near ambient pressure (NAP)-XPS and -XAS reveal the formation of oxygen vacancies at elevated temperatures, followed by H2O dissociation and saturation of the oxygen vacancies with chemisorbing OH. Through repeated heating and cooling, OH-saturated oxygen vacancies act as precursors for the formation of thermally stable NiOOH on the sample surface. This is accompanied by a significant restructuring of the surface which increases the probability of NiOOH formation. Exposure of a thin NiOx film to H2O can lead to a partial reduction of NiOx to metallic Ni accompanied by a distinct shift of the NiOx spectra with respect to the Fermi edge. DFT calculations show that the formation of oxygen vacancies and subsequently Ni0 leads to a state within the band gap of NiO which pins the Fermi edge. © the Owner Societies 2023

Global identifier:

Doi(
    "10.60810/openumwelt-1932",
)

Types:

Origin: /Bund/UBA/openUMWELT

Tags: Tierhaltungsanlage ? Sauerstoff ? Wasserdampf ? Blei ? Vorläufersubstanz ? Dissoziation ? Chemische Stoffeigenschaft ? Flächenheizung ? Atmosphäre ?

License: unbekannt

Language: Englisch/English

Persons

• Blume, A. Raoul (Verfasser*in)
• Calvet, Wolfram (Verfasser*in)
• Ghafari, Aliakbar (Verfasser*in)

Issued: 2023-01-01

Time ranges: 2023-01-01 - 2023-01-01

Status

Aktiv

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