Precise Cooling Time Control in Joule Heating for Efficient Oxygen Evolution Reaction of High-Entropy Oxides

Area of Science:

• Materials Science
• Catalysis
• Electrochemistry

Background:

• High temperatures can degrade catalyst structure, limiting performance.
• Controlling synthesis conditions is crucial for effective catalysts.

Purpose of the Study:

• To develop a method for precise cooling time control in catalyst synthesis.
• To synthesize high-entropy oxide (HEO) catalysts with enhanced properties.

Main Methods:

• Utilizing a Joule heating device and Newton's law of cooling for precise temperature control.
• Synthesizing CoFeNiMnCr high-entropy oxide (HEO) catalysts.
• Employing in situ Raman spectroscopy to analyze catalyst transformation.

Main Results:

• Achieved precise cooling time control within seconds.
• Synthesized HEO with large surface area and abundant defect states.
• Developed HEO catalyst with low overpotential (219 mV at 10 mA cm⁻²) and high stability (320 h at 100 mA cm⁻²).
• Identified cooling time as more critical than heating time for OER activity.

Conclusions:

• Cooling time significantly impacts the oxygen evolution reaction (OER) activity of HEO catalysts.
• The synthesized HEO catalyst exhibits state-of-the-art OER performance.
• This work offers a new strategy for designing high-performance catalysts through controlled cooling.