Structure Sensitivity and Catalyst Restructuring for CO₂ Electro-reduction on Copper.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Copper (Cu) is a leading catalyst for CO2 electroreduction (CO2RR) to valuable multi-carbon products.
• The precise active sites and surface restructuring mechanisms of Cu catalysts during CO2RR remain debated.
• Understanding structure sensitivity is key to optimizing CO2RR performance.

Purpose of the Study:

• To elucidate the atomic-scale mechanisms governing CO2 electroreduction on copper surfaces.
• To identify the specific surface structures responsible for high catalytic activity and selectivity.
• To explain the in situ restructuring of copper catalysts under reaction conditions.

Main Methods:

• Atomic-scale simulations of surface energies and reaction kinetics.
• Theoretical calculations of reaction pathways.
• Experimental validation using ultra-high vacuum-prepared ultraclean Cu surfaces.

Main Results:

• CO2RR does not occur on perfect planar Cu(111) or Cu(100) surfaces, but on steps and kinks.
• Planar Cu surfaces restructure to active stepped surfaces under reaction conditions, driven by strong CO binding at defects.
• Active sites for CO2RR are square motifs adjacent to defects, exhibiting a synergistic effect.
• Step-edge orientation plays a critical role in directing reaction selectivity.

Conclusions:

• The study refines the understanding of CO2RR structural sensitivity on Cu at the atomic level.
• A self-activation mechanism involving catalyst restructuring is highlighted.
• The origin of in situ restructuring of Cu surfaces during CO2RR is elucidated, clarifying catalyst behavior.