Highly Active Nanoperovskite Catalysts for Oxygen Evolution Reaction: Insights into Activity and Stability of Ba0.5Sr0.5Co0.8Fe0.2O3 and PrBaCo2O6

TL;DR

This study compares two nanoperovskite catalysts, Ba0.5Sr0.5Co0.8Fe0.2O3 and PrBaCo2O6, revealing their activity, stability, and degradation mechanisms for oxygen evolution, combining experimental synthesis, operando spectroscopy, and theoretical thermodynamic analysis.

Contribution

It introduces a scalable synthesis method for highly active nanoperovskite catalysts and provides detailed insights into their stability and degradation mechanisms under operational conditions.

Findings

BSCF shows 50x higher activity than traditional methods.

BSCF maintains stability by surface reconstruction into oxyhydroxide layers.

PBCO exhibits high initial activity but degrades due to thermodynamic instability.

Abstract

It is shown that producing PrBaCo2O5 and Ba0.5Sr0.5Co0.8Fe0.2O3 nanoparticle by a scalable synthesis method leads to high mass activities for the oxygen evolution reaction with outstanding improvements by 10 and 50 times, respectively, compared to those prepared via the state of the art synthesis method. Here, detailed comparisons at both laboratory and industrial scales show that Ba0.5Sr0.5Co0.8Fe0.2O3 appears to be the most active and stable perovskite catalyst under alkaline conditions, while PrBaCo2O6 reveals thermodynamic instability described by the density functional theory based Pourbaix diagrams highlighting cation dissolution under oxygen evolution conditions. Operando Xray absorption spectroscopy is used in parallel to monitor electronic and structural changes of the catalysts during oxygen evolution reaction. The exceptional BSCF functional stability can be correlated to its thermodynamic metastability under oxygen evolution conditions as highlighted by Pourbaix diagram analysis. BSCF is able to dynamically self reconstruct its surface, leading to formation of Co based oxyhydroxide layers while retaining its structural stability. Differently, PBCO demonstrates a high initial oxygen evolution reaction activity while it undergoes a degradation process considering its thermodynamic instability under oxygen evolution conditions as anticipated by its Pourbaix diagram. Overall, this work demonstrates a synergetic approach of using both experimental and theoretical studies to understand the behavior of perovskite catalysts.