Activity-Stability Relationships in Oxide Electrocatalysts for Water Electrolysis

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• The oxygen evolution reaction (OER) is crucial for electrochemical energy conversion but is kinetically limited.
• A common challenge is the inverse relationship between OER catalyst activity and stability.
• Epitaxial catalysts offer atomic-level insights into structure-function relationships.

Purpose of the Study:

• To investigate the activity-stability dilemma in OER catalysts using model epitaxial systems.
• To explore how crystal facet and termination layer influence OER activity and stability.
• To identify strategies for overcoming the inverse activity-stability relationship.

Main Methods:

• Utilized model epitaxial catalysts, specifically perovskite oxides like La_0.6Sr_0.4CoO_3-δ and LaNiO_3-δ.
• Analyzed the dependence of OER activity and stability on crystal facet.
• Investigated the effect of varying termination layers (La-rich vs. Ni-rich).

Main Results:

• The inverse activity-stability relationship is not universally applicable to all perovskite oxides.
• For La_0.6Sr_0.4CoO_3-δ, facet-controlled catalysts followed the inverse relationship.
• For LaNiO_3-δ, the (111) facet exhibited both highest activity and stability.
• Simultaneous enhancement of activity and stability was achieved by tuning termination layers.

Conclusions:

• The inverse activity-stability relationship can be overcome in select materials through precise control of the solid-liquid interface.
• This finding revitalizes the search for earth-abundant catalysts for water electrolysis.
• Further material design strategies are needed for a general departure from inverse relationships in transition metal oxide OER catalysts.