Molybdate-mediated self-healing NiMoFeO/Ni electrodes for durable alkaline OER performance

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Oxygen evolution reaction (OER) is crucial for energy conversion.
• Developing stable and efficient electrocatalysts for OER in alkaline media remains a challenge.
• Nickel-iron oxyhydroxides (NiFeOOH) are promising OER catalysts but suffer from degradation.

Purpose of the Study:

• To investigate the role of dynamic molybdate chemistry in stabilizing reconstructed NiFeOOH during alkaline OER.
• To elucidate the self-healing mechanism in NiMoFeO/Ni electrodes.
• To evaluate the catalytic performance and durability of the self-healing electrode system.

Main Methods:

• Electrochemical synthesis of NiMoFeO/Ni electrodes.
• In-situ/operando electrochemical characterization techniques.
• Analysis of catalyst reconstruction and active species regeneration.

Main Results:

• Demonstrated reversible molybdate (MoO4^2-) leaching and redeposition.
• Showcased restoration of Ni^3+-rich active species and improved charge transfer.
• Achieved low overpotential (221 mV at 10 mA cm^-2) and sustained high current density (500 mA cm^-2 for 300 h).

Conclusions:

• Dynamic molybdate chemistry is key to the self-healing of NiFeOOH electrocatalysts.
• The NiMoFeO/Ni electrode exhibits exceptional activity and long-term stability for alkaline OER.
• This work offers a promising strategy for designing robust electrocatalysts for energy applications.