  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.
