Molecular Assembled Electrocatalyst for Highly Selective CO₂ Fixation to C₂₊ Products

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Metalloenzymes utilize multimetal centers for efficient carbon-carbon coupling.
• Molecular electrocatalysts rarely achieve similar selectivity in CO2 fixation.
• Developing efficient molecular catalysts for CO2 reduction remains a challenge.

Purpose of the Study:

• To synthesize and characterize novel rod-shaped nanocatalysts with multiple copper centers.
• To investigate the electrochemical CO2 fixation performance of these molecularly assembled catalysts.
• To elucidate the mechanism behind the enhanced catalytic activity and selectivity.

Main Methods:

• Synthesis of triphenylphosphine copper complex (CuPPh) and its molecular assembly into nanorods.
• Electrochemical CO2 reduction experiments in aqueous solution.
• Characterization using density functional theory (DFT) calculations, in situ X-ray absorption spectroscopy (XAS), and quasi-in situ X-ray photoelectron spectroscopy (XPS).
• Reaction intermediate capture to identify key species.

Main Results:

• The assembled CuPPh nanorods exhibited excellent electrochemical CO2 fixation, producing C2+ hydrocarbons (ethene) and oxygenates (ethanol).
• Multiple copper centers within the nanorod assemblies were identified as crucial for catalytic performance.
• A CO2 transfer-coupling mechanism involving an oxalate intermediate was proposed, explaining the efficient C-C coupling.
• High activity, stability, and a Faradaic efficiency of 65.4% for C2+ products were achieved.

Conclusions:

• Molecularly assembled CuPPh nanorods mimic metalloenzyme active sites for selective CO2 reduction.
• The dynamic and cooperative function of double copper centers is key to C-C bond formation.
• This study provides a pathway for designing advanced molecular catalysts for CO2 utilization.