Band-Engineered LaFeO$_{3}$-LaNiO$_{3}$ Thin Film Interfaces for Electrocatalysis of Water

TL;DR

This study demonstrates that engineering band alignment in LaFeO₃/LaNiO₃ heterostructures significantly enhances their water oxidation catalytic performance, combining theoretical predictions with experimental validation.

Contribution

The paper introduces a novel approach of interfacial band engineering in LaFeO₃/LaNiO₃ heterostructures to improve electrocatalytic water splitting efficiency.

Findings

Valence band offset of 0.3 eV measured experimentally.

Catalytic current density increased by ~275 times.

Density functional theory predicts improved hole transport.

Abstract

Transition metal oxides have generated significant interest for their potential as catalysts for the oxygen evolution reaction (OER) in alkaline environments. Iron and nickel-based perovskite oxides have proven particularly promising, with catalytic over-potentials rivaling precious metal catalysts when the alignment of the valence band relative to the OER reaction potential is tuned through substitutional doping or alloying. Here we report that engineering of band alignment in LaFeO$_{3}$/LaNiO$_{3}$ (LFO/LNO) heterostructures via interfacial doping yields greatly enhanced catalytic performance. Using density functional theory modeling, we predict a 0.2 eV valence band offset (VBO) between metallic LNO and semiconducting LFO that significantly lowers the barrier for hole transport through LFO compared to the intrinsic material and make LFO a p-type semiconductor. Experimental band alignment measurements using in situ X-ray photoelectron spectroscopy of epitaxial LFO/LNO heterostructures agree quite well with these predictions, producing a measured VBO of 0.3(1) eV. OER catalytic measurements on the same samples in alkaline solution show an increase in catalytic current density by a factor of ~275 compared to LFO grown on n-type Nb-doped SrTiO$_{3}$. These results demonstrate the power of tuning band alignments through interfacial band engineering for improved catalytic