Structural Changes of NiFe Layered Double Hydroxides During the Oxygen Evolution Reaction: A Diffraction and Total...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Nickel-iron layered double hydroxides (NiFe-LDHs) are effective electrocatalysts for the oxygen evolution reaction (OER) in alkaline environments.
• Understanding the structural dynamics of NiFe-LDHs under operating conditions is crucial for optimizing their catalytic performance.

Purpose of the Study:

• To investigate the atomic structure and dynamic transformations of NiFe-LDHs during the OER.
• To correlate structural changes with catalytic activity and stability.

Main Methods:

• Operando X-ray diffraction (XRD) and X-ray total scattering were employed.
• Pair Distribution Function (PDF) analysis was utilized to probe atomic-level structural details.

Main Results:

• XRD revealed a reversible phase transition from the alpha-LDH to the gamma-LDH phase, accompanied by interlayer contraction under oxidative potential.
• PDF analysis indicated an irreversible increase in stacking disorder and a decrease in LDH sheet size.
• These changes signify particle breakdown and reduced crystallite size under operating conditions.

Conclusions:

• The study elucidates the structural evolution of NiFe-LDHs during OER, highlighting both reversible and irreversible transformations.
• Operating conditions lead to particle degradation, impacting the long-term stability and performance of these electrocatalysts.