Cerium driven active site relocation in spinel Co₃O₄ enables stable chlorine evolution in acidic media

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• The chlorine evolution reaction (CER) is vital for the chlor-alkali industry.
• Harsh reaction conditions limit the stability of non-noble catalysts.
• Developing robust and efficient catalysts is essential for industrial applications.

Purpose of the Study:

• To engineer a stable and active non-noble catalyst for the chlorine evolution reaction.
• To investigate the role of atomically dispersed cerium in spinel cobalt oxide.
• To enhance catalyst performance under industrially relevant conditions.

Main Methods:

• Synthesis of a three-dimensional ordered macroporous cobalt oxide (Co₃O₄) nanostructure doped with atomically dispersed cerium (Ce).
• Electrochemical characterization including overpotential measurements and selectivity tests in 4 M NaCl at pH 2.
• In situ spectroscopic techniques (Raman, ATR-SEIRAS) and differential electrochemical mass spectrometry (DEMS) for mechanistic studies.
• Density functional theory (DFT) calculations to elucidate reaction mechanisms and stability.

Main Results:

• The Ce-doped Co₃O₄ catalyst demonstrated significantly enhanced activity and stability for CER.
• Achieved low overpotentials of 44 mV (10 mA cm⁻²) and 218 mV (1000 mA cm⁻²).
• Maintained ~99.1% chlorine selectivity and robust durability over 550 hours in a chlor-alkali cell.
• Active site transformation to cobalt centers and optimized chloride adsorption were confirmed.

Conclusions:

• Atomically dispersed Ce in Co₃O₄ triggers active site relocation, enhancing CER activity and suppressing degradation.
• The engineered catalyst exhibits superior performance and durability compared to conventional non-noble catalysts.
• This active-site engineering approach provides a pathway for developing advanced catalysts for chlorine production.