Linking surface chemistry to photovoltage in Sr-substituted LaFeO3 for water oxidation

Kelsey A. Stoerzinger, Le Wang, Yifan Ye, Mark Bowden, Ethan J. Crumlin, Yingge Du, Scott A. Chambers

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

Perovskite oxides are promising materials for photoabsorbers and electrocatalysts for solar-driven water oxidation. Aliovalent doping can tune the transition metal redox properties as well as the material band gap and conductivity, resulting in a rich phase space of possible water-oxidation photoanodes. We consider the substitution of Sr2+ for La3+ in LaFeO3 epitaxial thin films, where the well-defined nature of the flat surface and path for charge transport enables fundamental studies of photoelectrochemical (PEC) water oxidation. Sr incorporation increases the photovoltage, but at the expense of photocurrent. The use of a fast redox couple to efficiently collect photogenerated holes indicates an even lower onset of oxidative current; the difference between this onset and that of water oxidation arises from the involvement of surface states during water oxidation. Measurements of the surface speciation in a humid environment demonstrate that Sr incorporation also promotes hydroxylation, suggesting that water oxidation proceeds through the oxidation of FeIII-OH states, which is facilitated by Sr incorporation and results in an increased photovoltage.

Original languageEnglish (US)
Pages (from-to)22170-22178
Number of pages9
JournalJournal of Materials Chemistry A
Volume6
Issue number44
DOIs
StatePublished - 2018
Externally publishedYes

Bibliographical note

Funding Information:
The thin lm growth and structural characterization work was supported by the U.S. Department of Energy (DOE), Office of Science, Division of Materials Sciences and Engineering under award #10122. PEC and AP-XPS measurements performed by K. A. S. were supported by the Linus Pauling Distinguished Postdoctoral Fellowship at Pacic Northwest National Laboratory (PNNL LDRD 69319). Y. D. acknowledges the support by U.S. DOE, Office of Science, Office of Basic Energy Sciences, Early Career Research Program under award No. 68278 for traveling to ALS and participating in the AP-XPS measurements. A portion of the work was performed at the W. R. Wiley Environmental Molecular Sciences Laboratory, a DOE User Facility sponsored by the Office of Biological and Environmental Research (DE-AC05-76RL01830). PNNL is a multi-program national laboratory operated for DOE by Battelle. This research used resources of the Advanced Light Source, which is a DOE Office of Science User Facility under contract no. DE-AC02-05CH11231.

Publisher Copyright:
© 2018 The Royal Society of Chemistry.

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