Two-dimensional Cu-phenylalanine nanoflakes for efficient and robust CO₂ electroreduction to C₂₊ products

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Electrocatalytic reduction of carbon dioxide (CO2) to multicarbon (C2+) products is crucial for sustainable chemical synthesis.
• Achieving high selectivity and stability for C2+ products remains a significant challenge.
• The moderate oxidation state of copper (Cu+) is key for C-C coupling, but Cu+ species are often unstable during reactions.

Purpose of the Study:

• To design and synthesize a stable catalyst that promotes C-C coupling for enhanced CO2 electroreduction to C2+ products.
• To investigate the role of catalyst structure and coordination in maintaining the active oxidation state of copper.
• To evaluate the performance and stability of the developed catalyst in a flow cell system.

Main Methods:

• Preparation of two-dimensional (2D) copper-phenylalanine (Cu-phe) nanoflakes via assembly of Cu ions and phenylalanine.
• Characterization using X-ray absorption spectroscopy (XAS) to confirm oxidation state and coordination environment.
• Electrochemical evaluation in a flow cell to determine Faraday efficiency (FE) for C2+ products and assess stability.

Main Results:

• Successfully synthesized 2D Cu-phe nanoflakes with a confirmed moderate oxidation state and Cu-O/N coordination.
• Cu-phe nanoflakes demonstrated high FE for C2+ products, reaching 88.1% at -0.8 V.
• The catalyst exhibited excellent stability during the electrocatalytic CO2 reduction process.

Conclusions:

• The carboxylic ligand and stable Cu-N coordination in Cu-phe nanoflakes effectively maintain the moderate oxidation state of copper.
• Developed Cu-phe nanoflakes offer a promising pathway for designing stable and efficient electrocatalysts for CO2 conversion.
• This research provides valuable insights for creating catalysts for the production of high-value chemicals from CO2.