Transition metal oxides have long been an area of interest for water electrocatalysis through the oxygen evolution and oxygen reduction reactions. Iron oxides, such as LaFeO3, are particularly promising due to the favorable energy alignment of the valence and conduction bands comprised of Fe3+ cations and the visible light band gap of such materials. In this work, we examine the role of band alignment on the electrocatalytic oxygen evolution reaction (OER) in the intrinsic semiconductor LaFeO3 by growing epitaxial films of varying thicknesses on Nb-doped SrTiO3. Using cyclic voltammetry and electrochemical impedance spectroscopy, we find that there is a strong thickness dependence on the efficiency of electrocatalysis for OER. These measurements are understood based on interfacial band alignment in the system as confirmed by layer-resolved electron energy loss spectroscopy and electrochemical Mott-Schottky measurements. Our results demonstrate the importance of band engineering for the rational design of thin film electrocatalysts for renewable energy sources.
@article{arxiv.2108.09360,
title = {Thickness Dependent OER Electrocatalysis of Epitaxial LaFeO$_{3}$ Thin Films},
author = {Andricus R. Burton and Rajendra Paudel and Bethany Matthews and Michel Sassi and Steven R. Spurgeon and Byron H. Farnum and Ryan B. Comes},
journal= {arXiv preprint arXiv:2108.09360},
year = {2022}
}