Ensemble Effect in Bimetallic Electrocatalysts for CO₂ Reduction.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Alloying pure metals is key for designing advanced catalytic materials.
• Conventional alloy catalysts lack precise control over atomic structures of active sites.

Purpose of the Study:

• Investigate the active-site ensemble effect in bimetallic Pd-Au electrocatalysts for CO2 reduction.
• Synthesize Pd@Au electrocatalysts with controlled Pd ensemble sizes to study their impact on catalytic activity.

Main Methods:

• Synthesis of Pd@Au electrocatalysts by decorating Au nanoparticles with controlled Pd doses.
• Electrocatalytic evaluation of CO2 reduction to CO.
• Density Functional Theory (DFT) calculations to understand reaction mechanisms and active site properties.

Main Results:

• Catalytic activity for CO2 electroreduction to CO showed nonlinear dependence on Pd content.
• Pd@Au catalysts with varying Pd ensemble sizes exhibited tunable adsorption properties.
• DFT calculations indicated lower CO2 activation energy barriers for Pd@Au compared to pure Au.
• Pd@Au catalysts were less poisoned by CO intermediates compared to pure Pd.

Conclusions:

• An intermediate Pd ensemble size, like Pd dimers, balances CO2 activation and CO poisoning.
• Optimized Pd@Au electrocatalysts achieve the highest activity for CO2 reduction due to synergistic effects.
• Precise control over active site structure is crucial for designing efficient electrocatalysts.