Reversible Angle Distortion-Dependent Electrochemical CO₂ Reduction on Cobalt Phthalocyanine

Area of Science:

• Catalysis
• Materials Science
• Electrochemistry

Background:

• Elucidating reaction mechanisms is crucial for developing efficient catalysts for electrochemical carbon dioxide reduction.
• Understanding the dynamic structural and electronic changes in active sites under reaction conditions is essential for catalyst design.

Purpose of the Study:

• To quantitatively elucidate the atomic and electronic structure evolutions of cobalt phthalocyanine (CoPc) during electrochemical carbon dioxide reduction.
• To establish a structure-performance relationship for CoPc and highlight the utility of advanced X-ray spectroscopy.

Main Methods:

• Utilized *operando* valence-to-core X-ray emission spectroscopy (V2c-XES).
• Employed high energy-resolution fluorescence detected X-ray absorption near-edge structure (HERFD-XANES).
• Combined experimental spectroscopy with theoretical spectroscopic calculations.

Main Results:

• CoPc exhibits reversible angle distortion at the active site under reaction conditions, while metal-ligand bond lengths remain constant.
• These distortions alter the energy levels of split d orbitals and the electron density of molecular orbitals.
• The reversible bond angle changes correlate with CO Faraday efficiency, demonstrating catalyst robustness.

Conclusions:

• The study establishes a clear link between the dynamic structural changes (angle distortion) of CoPc and its catalytic performance in CO2 reduction.
• Findings provide insights for designing highly active and stable atomically dispersed catalysts.
• Highlights the power of high energy-resolution X-ray spectroscopy for analyzing metal-N-doped carbon catalysts under operando conditions.