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

Blume, A. R., Calvet, W., & Ghafari, A. (2023). Structural and chemical properties of NiOx thin films: the role of oxygen vacancies in NiOOH formation in a H2O atmosphere. Physical chemistry, chemical physics, 25 (2023). https://doi.org/10.60810/openumwelt-1932

Zusammenfassung englisch

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

URI

https://openumwelt.de/handle/123456789/1359

Sammlungen

Aufsätze

Komplettanzeige