Electrode reconstruction strategy for oxygen evolution reaction: maintaining Fe-CoOOH phase with intermediate-spin...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Efficient electrocatalysts are crucial for the oxygen evolution reaction (OER).
• Cobalt oxide typically converts to a less active phase (CoO2) under OER conditions, hindering kinetics.
• Maintaining the CoOOH phase and intermediate-spin (IS) state is key for high-performance cobalt-based OER catalysts.

Purpose of the Study:

• To develop a scalable strategy for fabricating electrodes that maintain the Fe-CoOOH phase and IS state under OER conditions.
• To investigate the phase and spin state transformations during OER using advanced spectroscopic techniques.
• To enhance the catalytic activity and stability of cobalt-based electrocatalysts for the OER.

Main Methods:

• Computational calculations and experimental studies.
• In-situ/operando X-ray based absorption spectroscopy and Raman spectroscopy.
• Electrochemical reconstruction of chalcogenide-treated cobalt foam electrodes.

Main Results:

• A simple and scalable fabrication strategy successfully maintained the Fe-CoOOH phase and IS state under OER.
• Operando spectroscopic analyses confirmed the phase and spin state stability.
• The reconstructed electrodes exhibited significantly enlarged active surface areas, leading to excellent catalytic activity and stability in large-scale water electrolyzers.

Conclusions:

• The study validates the importance of the CoOOH phase and IS state for efficient OER catalysis.
• The findings propose a novel electrode fabrication strategy for improved OER performance.
• Experimental verification of computational predictions using operando analyses highlights the significance of studying active phases under reaction conditions.