Oxide Heterostructures for Water Splitting: LaFeO₃ and LaNiO₃ Films and Interfaces

Renewable energy catalysis technologies are governed by oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). An electrocatalyst is desirable to carry out OER and ORR efficiently for energy production on a large scale without expensive metals such as Pt or Ir. Ideally, the electrocatalyst should have high earth abundance, low cost and high stability. Recent studies have shown metal oxides are efficient catalysts for OER and ORR and are less expensive. We synthesized perovskites LaNiO₃, LaFeO₃, and LaFeO₃/LaNiO₃ thin films to study the catalytic properties of these materials. These oxide thin films were grown using molecular beam epitaxy. In-situ XPS measurements were performed to ensure film stoichiometry and measure electronic properties. Cyclic voltammetry and electrochemical impedance spectroscopy were performed to study OER catalysis with these materials. Scanning transmission electron microscopy images have shown high stability of LaFeO₃ during electrocatalysis. We further studied band alignment at the LaFeO₃/LaNiO₃ interface using XPS as well as using density functional theory computations to understand the interface and its impact on applicability of these materials as catalysts in future energy technologies.