Local-strain-induced CO₂ adsorption geometries and electrochemical reduction pathway shift

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Understanding the electrochemical reduction of carbon dioxide (CO2RR) on bimetallic alloys is crucial for developing efficient catalysts.
• Local microenvironment variables, including strain and geometric effects, complicate the prediction of CO2RR selectivity on Cu-based and Pd-based alloys.

Purpose of the Study:

• To investigate how strain and geometric effects influence CO2RR selectivity on PdCu alloys.
• To elucidate the specific adsorption geometries and reaction pathways of CO2 on PdCu nanoparticles and nanodendrites.

Main Methods:

• Synthesis and characterization of PdCu nanoparticles and nanodendrites.
• Electrochemical experiments to determine CO2RR selectivity.
• In-situ spectroscopy to probe catalyst surface under reaction conditions.
• Density functional theory (DFT) calculations to model adsorption energies and reaction pathways.

Main Results:

• PdCu alloys with different geometries (nanoparticles vs. nanodendrites) exhibit distinct local strain profiles despite similar phases and facets.
• CO2 preferentially adsorbs with carbon-side geometry on tensile-strained areas, favoring a *COOH-to-CO pathway.
• CO2 adopts oxygen-side geometry on compressive-strained regions, promoting an *OCHO-to-HCOO pathway due to d-band center downshift.
• Catalysts with both adsorption geometries show a dominant *OCHO-to-HCOO- pathway.

Conclusions:

• Local strain environments in PdCu alloys are critical determinants of CO2RR selectivity.
• Distinct geometric morphologies lead to varied local strain, influencing CO2 adsorption and subsequent reaction pathways.
• This work provides a model for understanding bimetallic alloy microenvironments and their impact on CO2RR pathway shifts.