Polar Layered Intermetallic LaCo₂P₂ as a Water Oxidation Electrocatalyst

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• The oxygen evolution reaction (OER) is crucial for renewable energy technologies.
• Developing stable and efficient electrocatalysts for OER under various pH conditions remains a significant challenge.
• Layered intermetallic compounds offer potential as novel catalytic materials.

Purpose of the Study:

• To investigate the electrocatalytic activity and stability of LaCo2P2 for OER.
• To evaluate the performance of LaCo2P2 under both alkaline and acidic conditions.
• To understand the structural evolution of LaCo2P2 during OER.

Main Methods:

• Synthesis of LaCo2P2 via Sn-flux high-temperature annealing.
• Preparation of electrocatalytic ink with ball-milled LaCo2P2 at a mass loading of 0.25 mg/cm².
• Electrochemical characterization of OER activity and stability at pH 14 and pH 0.
• Analysis of catalyst structure using transmission electron microscopy (TEM).

Main Results:

• LaCo2P2 exhibits OER activity in alkaline media (pH=14), reaching 100 mA/cm² at 460 mV overpotential.
• The catalyst maintained stable performance for at least 4 days in alkaline conditions.
• TEM revealed the in situ formation of a CoOₓ shell on the LaCo2P2 core, acting as the active OER site.
• LaCo2P2 rapidly deteriorated in acidic conditions (pH=0), forming LaPO4 and amorphous cobalt oxide.

Conclusions:

• Layered intermetallics like LaCo2P2 can serve as robust supports for in situ-formed OER electrocatalysts.
• LaCo2P2 demonstrates significant potential for OER in alkaline environments.
• Further research is needed to enhance electrocatalytic performance and stability in acidic media.