Thickness-dependent photoelectrochemical water splitting on ultrathin LaFeO3 films grown on Nb:SrTiO3
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
The performance of photoelectrodes can be modified by changing the material chemistry, geometry, and interface engineering. Specifically, nanoscale active layers can facilitate the collection of charge carriers. In heterostructure devices, the multiple material interfaces are particularly important, which at present are not well understood for oxides. Here, we report a detailed study of ultrathin (2-25 nm) LaFeO3 films grown epitaxially on Nb-doped SrTiO3. The films exhibit thickness-dependence with sensitivity to less than 10 nm in both the through-plane charge transfer conductivity and in the potential-dependent photoresponse. Supplementing photoelectrochemical measurements with X-ray photoelectron spectroscopy, spectroscopic ellipsometry, and electrochemical impedance spectroscopy, we construct a band model that accounts for this thickness dependence via a shifting valence-band offset at the film-substrate interface and the potential-dependent overlap of the depletion regions present at both the film-substrate and film-electrolyte interfaces. Lastly, these results illustrate the utility of using active layer thickness and film-substrate interactions to tune the performance of photoelectrodes, providing insight for the design of efficient heterostructure oxide photoelectrochemical devices.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 1329125
- Journal Information:
- Journal of Physical Chemistry Letters, Vol. 6, Issue 6; ISSN 1948-7185
- Publisher:
- American Chemical Society
- Country of Publication:
- United States
- Language:
- English
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