The electrochemistry of iron oxide thin films nanostructured by high ion flux plasma exposure

TitleThe electrochemistry of iron oxide thin films nanostructured by high ion flux plasma exposure
Publication TypeJournal Article
Year of Publication2017
AuthorsR. Sinha, I. Tanyeli, R. Lavrijsen, M.CM van de Sanden, A. Bieberle
JournalElectrochimica Acta
Volume258
Pagination709-717
Date Published12/2017
KeywordsElectrochemical impedance spectroscopy, Hematite, Magnetron sputtering, Plasma exposure, water splitting
Abstract

Photo-electrochemical (PEC) water splitting of hematite photoanodes suffers from low performance and efficiency. One way to increase the performance is to increase the electrochemically active surface area available for the oxygen evolution reaction. In this study, we use high ion flux, low energy helium plasma exposure to nanostructure sputtered iron thin films. Subsequent annealing in air at 645 °C leads to the formation of PEC active hematite (α-Fe2O3) phase in these films. The surface area, as derived from electrochemical impedance spectroscopy (EIS), was seen to increase 10–40 times with plasma exposure. The photocurrent density increased by 2–5 times for the plasma exposed films as compared to the unexposed films. However, the less nanostructured film showed a higher photocurrent density. These findings were explained by detailed chemical and structural characterization in combination with electrochemical characterization and attributed to the presence of secondary elements in the film as well as to the presence of secondary iron oxide phases apart from hematite. This work demonstrates the complex effect of plasma exposure on both film morphology and chemical composition of PEC thin films and provides further understanding on how this technique can be used for nanostructuring of other functional films.

DOI10.1016/j.electacta.2017.11.117
Division

MaSF

Department

EMI

PID

b784807a07c51e282d3efe51a09c5512

Alternate TitleElectrochim. Acta

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