Semiconducting and electrocatalytic properties of sputtered cobalt oxide films

Cobalt oxide films, fabricated by reactive sputtering in a 100% pure O 2 plasma are highly nonstoichiometric with a bulk oxygen to cobalt ratio of ∼ 1.15. Conversely, surface XPS studies indicate an oxygen to cobalt ratio ranging from 1.8 to 3.0 and show the presence of Co 3+ only in the surface reg...

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Bibliographic Details
Published in:Electrochimica acta 1990, Vol.35 (6), p.975-984
Main Authors: Schumacher, Lynn C., Holzhueter, Ingo B., Hill, Ian R., Dignam, Michael J.
Format: Article
Language:English
Subjects:
Chemistry
Electrochemistry
Exact sciences and technology
General and physical chemistry
High temperature electrochemistry (including molten salts)
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Summary:Cobalt oxide films, fabricated by reactive sputtering in a 100% pure O 2 plasma are highly nonstoichiometric with a bulk oxygen to cobalt ratio of ∼ 1.15. Conversely, surface XPS studies indicate an oxygen to cobalt ratio ranging from 1.8 to 3.0 and show the presence of Co 3+ only in the surface region of the as formed films. Infrared and Raman spectra however confirm the presence of both Co 3+ and Co 2+ in the bulk and indicate that these highly defective films possess the spinel structure. Photoelectrochemical and impedance studies show that the sputtered oxide is a highly doped p-type semiconductor with an indirect bandgap of E g ∼ 1.50 eV. The electrocatalytic properties of these oxide films for oxygen reduction and evolution are reported.
ISSN:0013-4686
1873-3859
DOI:10.1016/0013-4686(90)90030-4