Selectivity in Electrochemical CO₂ Reduction

Area of Science:

• Electrochemistry and Catalysis
• Sustainable Chemistry and Carbon Capture
• Materials Science for Energy Applications

Background:

• Electrocatalytic CO2 reduction (CO2RR) is crucial for mitigating CO2 emissions and producing valuable carbon feedstocks.
• Current research focuses on improving catalyst selectivity for specific C1 products (CO, HCOOH, CH3OH, CH4) over competing reactions.
• Challenges include catalyst deactivation due to competing hydrogen evolution (HER) and oxygen reduction (ORR) under non-ideal conditions.

Purpose of the Study:

• To elucidate the mechanistic factors governing selectivity in electrocatalytic CO2 reduction.
• To establish structure-selectivity relationships for CO2RR catalysts.
• To demonstrate strategies for suppressing competing HER and ORR, favoring CO2RR.

Main Methods:

• Mechanistic investigations involving detection, trapping, and characterization of reaction intermediates.
• Spectroscopic analysis of intermediates to understand electronic structure effects on selectivity.
• Case studies using iron porphyrin and bioinspired non-heme mimics to examine spin state, hydrogen bonding, and heterogenization.

Main Results:

• Identified key intermediates and developed electronic structure-selectivity relationships for 2e-/2H+ CO2RR.
• Demonstrated the influence of spin state, hydrogen bonding, and heterogenization on CO2RR product distribution (CO, HCOOH, CH4).
• Showcased strategies to significantly enhance CO2RR selectivity over HER and ORR.

Conclusions:

• Understanding reaction intermediates and electronic structure is vital for designing selective CO2RR catalysts.
• Catalyst design can be tuned to favor specific products and suppress unwanted side reactions.
• This work provides a framework for developing efficient and selective electrocatalytic CO2 conversion systems.