Simultaneously Improved Surface and Bulk Participation of Evolved Perovskite Oxide for Boosting Oxygen Evolution Reaction Activity Using a Dynamic Cation Exchange Strategy.

Perovskite oxides are intriguing electrocatalysts for the oxygen evolution reaction, but both surface (e.g., composition) and bulk (e.g., lattice oxygen) properties should be optimized to maximize their participation in offering favorable activity and durability. In this work, it is demonstrated that through introducing exogenous Fe 3+ ( Fe exo 3 + ${\rm{Fe}}_{{\rm{exo}}}^{3 + }$ ) into the liquid electrolyte, not only is the reconstructed surface stabilized and optimized, but the lattice oxygen diffusion is also accelerated. As a result, compared to that in Fe-free 0.1 m KOH, PrBa 0.5 Sr 0.5 Co 2 O 5+δ in 0.1 m KOH + 0.1 mm Fe 3+ demonstrates a tenfold increment in activity, an extremely low Tafel slope of ≈50 mV dec -1 , and outstanding stability at 10.0 mA cm -2  for 10 h. The superior activity and stability are further demonstrated in Zn-air batteries by presenting high open-circuit voltage, narrow potential gap, high power output, and long-term cycle stability (500 cycles). Based on experimental and theoretical calculations, it is discovered that the dynamical interaction between the Co hydr(oxy)oxide from surface reconstruction and intentional Fe 3+ from the electrolyte plays an important role in the enhanced activity and durability, while the generation of a perovskite-hydr(oxy)oxide heterostructure improves the lattice oxygen diffusion to facilitate lattice oxygen participation and enhances the stability.