Enhanced bifunctional oxygen catalysis in strained LaNiO3 perovskites

TL;DR

This study demonstrates that applying compressive strain to LaNiO3 perovskites enhances their bifunctional oxygen catalytic activity, surpassing noble metals, by altering electronic orbital structures.

Contribution

It reveals how strain-induced eg orbital splitting in LaNiO3 improves bifunctional oxygen catalysis, a novel insight into strain effects on transition metal oxides.

Findings

Compressive strain significantly enhances oxygen reduction and evolution reactions.

Strain-induced eg orbital splitting correlates with improved catalytic activity.

LaNiO3 under strain outperforms noble metal catalysts in bifunctional activity.

Abstract

Strain is known to greatly influence low temperature oxygen electrocatalysis on noble metal films, leading to significant enhancements in bifunctional activity essential for fuel cells and metal-air batteries. However, its catalytic impact on transition metal oxide thin films, such as perovskites, is not widely understood. Here, we epitaxially strain the conducting perovskite LaNiO3 to systematically determine its influence on both the oxygen reduction and oxygen evolution reaction. Uniquely, we found that compressive strain could significantly enhance both reactions, yielding a bifunctional catalyst that surpasses the performance of noble metals such as Pt. We attribute the improved bifunctionality to strain-induced splitting of the eg orbitals, which can customize orbital asymmetry at the surface. Analogous to strain-induced shifts in the d-band center of noble metals relative to Fermi level, such splitting can dramatically affect catalytic activity in this perovskite and other potentially more active oxides.