Operando X-ray Absorption Spectroscopy (XAS) Observation of Photoinduced Oxidation in FeNi (Oxy)hydroxide Overlayers on Hematite (α-Fe2O3) Photoanodes for Solar Water Splitting
An FeNi (oxy)hydroxide cocatalyst overlayer was photoelectrochemically deposited on a thin-film hematite (α-Fe2O3) photoanode, leading to a cathodic shift of ∼100 mV in the photocurrent onset potential. Operando X-ray absorption spectroscopy (XAS) at the Fe and Ni K-edges was used to study the chang...
| Veröffentlicht in: | Langmuir : the ACS journal of surfaces and colloids. - 1992. - 36(2020), 39 vom: 06. Okt., Seite 11564-11572 |
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| Weitere Verfasser: | , , , , , , |
| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2020
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| Zugriff auf das übergeordnete Werk: | Langmuir : the ACS journal of surfaces and colloids |
| Schlagworte: | Journal Article |
| Zusammenfassung: | An FeNi (oxy)hydroxide cocatalyst overlayer was photoelectrochemically deposited on a thin-film hematite (α-Fe2O3) photoanode, leading to a cathodic shift of ∼100 mV in the photocurrent onset potential. Operando X-ray absorption spectroscopy (XAS) at the Fe and Ni K-edges was used to study the changes in the overlayer with potential in the dark and under illumination conditions. Potential or illumination only had a minor effect on the Fe oxidation state, suggesting that Fe atoms do not accumulate significant amount of charge over the whole potential range. In contrast, the Ni K-edge spectra showed pronounced dependence on potential in the dark and under illumination. The effect of illumination is to shift the onset for the Ni oxidation because of the generated photovoltage and suggests that holes that are photogenerated in hematite are transferred mainly to the Ni atoms in the overlayer. The increase in the oxidation state of Ni proceeds at potentials corresponding to the redox wave of Ni, which occurs immediately prior to the onset of the oxygen evolution reaction (OER). Linear combination fitting analysis of the obtained spectra suggests that the overlayer does not have to be fully oxidized to promote oxygen evolution. Cathodic discharge measurements show that the photogenerated charge is stored almost exclusively in the Ni atoms within the volume of the overlayer |
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| Beschreibung: | Date Revised 28.10.2020 published: Print-Electronic ErratumIn: Langmuir. 2020 Nov 24;36(46):14155. - PMID 33180510 Citation Status PubMed-not-MEDLINE |
| ISSN: | 1520-5827 |
| DOI: | 10.1021/acs.langmuir.0c02065 |