Core-shell CoFe₂O₄@Co-Fe-Bi nanoarray: a surface-amorphization water oxidation catalyst operating at near-neutral pH

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing efficient and earth-abundant water oxidation catalysts is crucial for sustainable energy solutions.
• Existing catalysts often require harsh conditions or are based on scarce precious metals.

Purpose of the Study:

• To fabricate and evaluate a novel core-shell cobalt-iron-bismuth nanoarray on carbon cloth (CoFe2O4@Co-Fe-Bi/CC) as a high-performance water oxidation electrode.
• To investigate the catalytic activity, durability, and underlying mechanism of the synthesized material.

Main Methods:

• In situ surface amorphization of a CoFe2O4 nanoarray on carbon cloth.
• Electrochemical characterization including overpotential and current density measurements.
• Density functional theory (DFT) calculations to elucidate the reaction mechanism.

Main Results:

• The CoFe2O4@Co-Fe-Bi/CC electrode exhibited outstanding water oxidation activity, requiring an overpotential of 460 mV to achieve a current density of 10 mA cm-2.
• The catalyst demonstrated superior long-term durability, maintaining performance for over 20 hours with 96% Faradaic efficiency.
• DFT calculations identified the OOH* to O2 conversion as the rate-limiting step, with a lower free energy of 1.84 eV on the Co-Fe-Bi shell contributing to high activity.

Conclusions:

• The core-shell CoFe2O4@Co-Fe-Bi/CC nanoarray is a highly effective and durable electrocatalyst for water oxidation under mild conditions.
• The synergistic effect between the core-shell structure and the earth-abundant elements enhances catalytic performance.
• This work provides a promising pathway for developing advanced electrocatalysts for clean energy applications.