Triggering Spontaneous Reconstruction of Ruddlesden-Popper Perovskites for Enhanced Oxygen Evolution.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Catalyst reconstruction is vital for designing efficient oxygen evolution reaction (OER) electrocatalysts.
• Spontaneous chemical reconstruction in alkaline media is not well understood.

Purpose of the Study:

• To investigate alkali-triggered chemical reconstruction for generating active OER species.
• To understand the link between dynamic structural evolution and catalytic performance.

Main Methods:

• Used Ruddlesden-Popper perovskite La0.5Sr1.5Ni0.75Fe0.25O4 ± δ (LSNF) as a model catalyst.
• Applied KOH immersion and characterized the catalyst using spectroscopic and microscopic analyses.
• Tested the general applicability on other perovskite compositions (La1-xSrxNi0.75Fe0.25O3-δ).

Main Results:

• KOH immersion enhanced OER current density by approximately 17-fold at 1.55 V vs RHE.
• Achieved a reduced overpotential of 287 mV at 10 mA cm⁻², 86 mV lower than pristine LSNF.
• Identified KOH immersion-induced elemental leaching and Ni reconfiguration, forming an amorphous Ni hydr(oxy)oxide layer enriched with Fe.

Conclusions:

• Alkali-triggered chemical reconstruction is more effective than electrochemical activation for generating active OER species.
• Concentrated alkali plays a key role in driving catalyst reconstruction and dynamic structural evolution.
• The strategy is broadly applicable to various perovskite materials for improved OER electrocatalysis.