Reconstruction of Ferromagnetic/Paramagnetic Cobalt-Based Electrocatalysts under Gradient Magnetic Fields for...

Area of Science:

• Materials Science
• Catalysis
• Electrochemistry

Background:

• Efficient water oxidation is crucial for energy conversion technologies.
• Catalyst surface reconstruction under reaction conditions is key but challenging to control.
• Electrochemical oxygen evolution reaction (OER) is a critical bottleneck in water splitting.

Purpose of the Study:

• To develop a novel in situ catalyst reconstruction strategy using a gradient magnetic field.
• To enhance the catalytic activity and stability of ferromagnetic/paramagnetic core-shell catalysts for OER.
• To investigate the mechanism of magnetic field-modulated surface reconstruction and its effect on active sites.

Main Methods:

• Utilized a ferromagnetic/paramagnetic CoFe2O4@CoBDC core-shell structure.
• Applied an in situ reconstruction strategy under a gradient magnetic field.
• Analyzed surface reconstruction using Kelvin force microscopy and electrochemical performance testing.

Main Results:

• Gradient magnetic field induced surface reconstruction, increasing the proportion of Co2+ active sites.
• Optimized Co sites exhibited favorable adsorption energies and reduced activation energy for OER.
• Achieved a 128% current density increase at 1.63 V and a 28 mV overpotential reduction at 10 mA cm−2.
• Catalytic activity persisted for over 100 hours after removing the magnetic field.

Conclusions:

• Directional surface reconstruction of catalysts can be achieved using a gradient magnetic field.
• This strategy significantly enhances electrochemical oxygen evolution reaction performance.
• The method offers a promising approach for designing highly efficient water oxidation catalysts.