Size-dependent electrocatalytic reduction of CO2 over Pd nanoparticles

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Nanoparticle size influences catalytic properties.
• Understanding size effects in CO2 electroreduction is vital for renewable energy and carbon utilization.
• Palladium nanoparticles (Pd NPs) are key catalysts for CO2 reduction.

Purpose of the Study:

• Investigate the prominent size-dependent activity and selectivity of Pd NPs in CO2 electroreduction.
• Determine the optimal Pd NP size for efficient CO production.
• Elucidate the relationship between NP surface structure and catalytic performance.

Main Methods:

• Electrocatalytic CO2 reduction experiments with Pd NPs of varying sizes (2.4–10.3 nm).
• Density Functional Theory (DFT) calculations to analyze reaction mechanisms and energetics.
• Analysis of Faradaic efficiency, current density, and turnover frequency.

Main Results:

• Faradaic efficiency for CO production increased from 5.8% (10.3 nm NPs) to 91.2% (3.7 nm NPs).
• Current density showed an 18.4-fold increase with decreasing NP size.
• DFT calculations revealed easier CO2 adsorption and COOH* intermediate formation on edge/corner sites compared to terrace sites.

Conclusions:

• Pd NP size is a critical factor in tuning CO2 electroreduction activity and selectivity.
• Smaller Pd NPs with a higher ratio of edge/corner sites are more effective for CO production.
• Controlling NP size allows optimization of CO2 adsorption, intermediate formation, and product removal for enhanced catalysis.