Dynamic Redeposition Over Bidirectional Amorphous NiFe-Oxides toward Surface Self-Healing for the Alkaline Oxygen...

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Nickel-iron oxy/hydroxides (NiFeO_xH_y) show promise for alkaline oxygen evolution reactions (OER).
• A major challenge for NiFeO_xH_y in OER is irreversible metal dissolution, limiting long-term stability.

Purpose of the Study:

• To develop a self-supported electrode with enhanced activity and stability for alkaline OER.
• To investigate a novel self-healing mechanism to mitigate metal dissolution in NiFeO_xH_y catalysts.

Main Methods:

• Fabrication of a self-supported electrode comprising NiFeO_xH_y/FeNiO_x/SS-A.
• Characterization of the electrode's self-healing property, activity, and stability under OER conditions.
• Analysis of the role of the amorphous FeNiO_x interlayer in crack repair and ion redeposition.

Main Results:

• The fabricated electrode exhibited a rare self-healing property, repairing surface cracks.
• Crack repair was driven by the redeposition of dissolved Fe and Ni ions from the amorphous interlayer.
• The electrode demonstrated excellent activity and stability, with 71% crack repair after 72 hours at 500 mA cm^-2, effectively suppressing dissolution.

Conclusions:

• The amorphous FeNiO_x interlayer is crucial for the self-healing mechanism and improved stability of NiFeO_xH_y OER catalysts.
• This self-healing strategy offers a promising avenue for designing and developing highly efficient and durable alkaline OER electrodes.