Switching Product Selectivity in CO₂ Electroreduction via Cu-S Bond Length Variation

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Controlling selectivity in electrochemical CO2 reduction is vital for sustainable chemical production.
• Copper sulfide (CuS) is a promising catalyst, but its selectivity needs optimization.

Purpose of the Study:

• To investigate the effect of antimony (Sb) incorporation into CuS on the selectivity of electrochemical CO2 reduction.
• To elucidate the relationship between Cu-S bond length and product selectivity.

Main Methods:

• Synthesis of Sb-doped CuS (Cu3SbS4) and pristine CuS.
• Electrochemical characterization including Faradaic efficiency measurements.
• In situ spectroscopy and density functional theory (DFT) calculations.

Main Results:

• CuS exhibited high selectivity for formic acid (HCOOH) production (72% FE) due to a shorter Cu-S bond (2.24 Å).
• Cu3SbS4 showed enhanced selectivity for carbon monoxide (CO) production (60% FE) with an elongated Cu-S bond (2.30 Å).
• DFT calculations revealed weaker *HCOO binding on Cu3SbS4, facilitating CO production.

Conclusions:

• Antimony incorporation in CuS effectively tunes the Cu-S bond length and local coordination environment.
• Altered Cu-S bond length in Cu3SbS4 promotes *COOH adsorption, leading to high CO selectivity.
• This study provides insights into rational catalyst design for selective electrochemical CO2 reduction.