Size-Dependent Activity and Selectivity of Atomic-Level Copper Nanoclusters during CO/CO₂ Electroreduction

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Copper catalysts are crucial for regulating CO2 electroreduction reactions (CO2RR).
• Controlling copper nanocluster size at the atomic level for CO2RR remains challenging.
• The size effect of copper catalysts is a key factor in activity and selectivity.

Purpose of the Study:

• To synthesize size-gradient copper catalysts (single atoms to nanoclusters) on a graphdiyne matrix.
• To investigate the impact of copper nanocluster size on CO2RR activity and selectivity.
• To elucidate the atomic-level mechanisms governing CO2RR based on size-activity/selectivity relationships.

Main Methods:

• Acetylenic-bond-directed site-trapping approach for catalyst synthesis.
• Preparation of size-gradient copper catalysts: single atoms (SAs), subnanometric clusters (SCs, 0.5-1 nm), and nanoclusters (NCs, 1-1.5 nm).
• Electrocatalytic measurements to evaluate CO2RR performance.

Main Results:

• Demonstrated a significant size effect of copper catalysts on CO2RR activity and selectivity.
• Observed improved catalytic activity and selectivity towards C2+ products with increasing copper nanocluster size.
• Achieved a high C2+ conversion rate of 312 mA cm⁻² with 91.2% Faradaic efficiency at -1.0 V vs RHE using Cu NCs.

Conclusions:

• Copper nanocluster size is a critical parameter for optimizing CO2RR.
• Increasing copper nanocluster size enhances both activity and selectivity for C2+ production.
• The study provides fundamental insights into CO2RR mechanisms at the atomic scale through size-dependent performance analysis.