Atomically Precise Cu(I) Clusters Facilitated by CeO₂-Derived Reverse Hydrogen Spillover for Selective...

Area of Science:

• Materials Science
• Catalysis
• Electrochemistry

Background:

• Atomically precise copper clusters offer tunable electronic properties for catalysis.
• Stabilized low-coordinated Cu+ species are crucial for efficient CO2 reduction.
• Enhancing product selectivity in CO2 electroreduction remains a significant challenge.

Purpose of the Study:

• To construct and investigate two novel copper clusters, Cu15 and Cu18, for deep CO2 reduction.
• To enhance methane selectivity in CO2 electroreduction through cerium dioxide (CeO2) incorporation.
• To elucidate the catalytic mechanism and the role of CeO2 in promoting methane formation.

Main Methods:

• Ligand-mediated assembly of Cu3 triangular units to synthesize Cu15 and Cu18 clusters.
• Electrochemical CO2 reduction experiments to evaluate catalytic performance and product selectivity.
• In situ XAS and ex situ XPS analysis to characterize the electronic state of copper species.
• Kinetic analysis and theoretical calculations (DFT) to understand reaction mechanisms.

Main Results:

• Both Cu15 and Cu18 clusters effectively catalyzed deep CO2 reduction, with methane (CH4) as the dominant product.
• CeO2 incorporation significantly enhanced CH4 selectivity, achieving 78.5% for Cu15/CeO2 and 64.3% for Cu18/CeO2.
• Stabilized Cu+ species and *CO intermediate stabilization were confirmed under CO2 reduction conditions.
• Isolated Cu sites in Cu15 were identified as active centers, operating via Langmuir-Hinshelwood mechanism.
• CeO2 facilitated water activation and hydrogen spillover to sulfur sites, accelerating *CO hydrogenation.

Conclusions:

• Atomically precise copper clusters, particularly Cu15, are promising electrocatalysts for CO2 to CH4 conversion.
• CeO2 acts as a synergistic promoter, enhancing CH4 selectivity through improved water activation and hydrogen spillover.
• Understanding the interplay between copper cluster structure, CeO2 support, and reaction intermediates is key to designing efficient CO2 reduction catalysts.