Mechanistic Insights into Acetate Selectivity on Intermetallic CuPd(110) in CO Reduction

Area of Science:

• Materials Science
• Catalysis
• Computational Chemistry

Background:

• Copper (Cu) catalysts primarily produce ethylene during carbon monoxide reduction (CORR).
• Copper-palladium (CuPd) alloy surfaces exhibit unique selectivity towards acetate formation in CORR.
• Understanding the mechanistic basis for this selectivity is crucial for catalyst design.

Purpose of the Study:

• To elucidate the reaction mechanism and selectivity of acetate formation on CuPd(110) during CORR.
• To compare the reaction pathways on CuPd(110) with those on Cu(111) surfaces.
• To identify key intermediates and thermodynamic/kinetic factors governing product distribution.

Main Methods:

• Explicit solvation density functional theory (DFT) calculations were employed.
• Both thermodynamic and kinetic analyses were performed to investigate the reaction mechanism.
• Electron density difference analyses were used to understand protonation preferences.

Main Results:

• On CuPd(110), the acetate pathway intermediate (H₂CCO) is thermodynamically favored under experimental conditions.
• On Cu(111), the ethylene precursor intermediate (CHCHO) is preferred.
• H₂CCO is kinetically accessible on CuPd(110), facilitating acetate formation.
• Distinct protonation preferences were identified, supporting the proposed mechanism.

Conclusions:

• The thermodynamic favorability of H₂CCO over CHCHO on CuPd(110) drives acetate selectivity.
• Kinetic accessibility of H₂CCO further enhances acetate formation.
• A thermodynamic screening parameter (G_H2CCO < G_CHCHO) is proposed for designing selective Cu-based catalysts.
• The study provides mechanistic insights into CORR product selectivity and a framework for catalyst development.