Multifunctional Binding Interface Drives Near-Unity CO Selectivity in Acidic CO₂ Electrolysis

Area of Science:

• Electrocatalysis
• Carbon Dioxide Reduction
• Green Chemistry

Background:

• Electrocatalytic carbon dioxide (CO2) reduction is crucial for sustainable energy, but is hindered by the competing hydrogen evolution reaction (HER), particularly in acidic environments.
• Developing efficient catalysts that can selectively convert CO2 while suppressing HER is a significant challenge in electrochemistry.

Purpose of the Study:

• To investigate the use of redox-active isoindigo as a multifunctional co-catalyst for electrocatalytic CO2 reduction.
• To elucidate the mechanisms by which isoindigo enhances CO2 activation and suppresses HER.
• To optimize catalyst design for improved CO2 reduction performance, focusing on selectivity and efficiency.

Main Methods:

• Modification of silver catalysts with isoindigo.
• Electrochemical characterization and analysis of catalytic performance at various pH values.
• Investigation of synergistic effects including Lewis acid-base adduct formation, intramolecular hydrogen bonding, and interfacial water structure modulation.
• Implementation of a polyamine-coated layer to enhance CO2 transport.

Main Results:

• Isoindigo significantly decreases the energy barrier for CO2 to *COOH conversion, a key step in CO production.
• Superior catalytic performance achieved at pH 2, with Faradaic efficiencies exceeding 99% at industrial current densities.
• The polyamine-coated layer improved CO2 transport, optimizing the balance between conversion and selectivity.

Conclusions:

• Isoindigo acts as an effective multifunctional co-catalyst, enhancing CO2 reduction and suppressing HER through synergistic mechanisms.
• The modified silver catalyst demonstrates high efficiency and selectivity for CO2 reduction in acidic media.
• Catalyst design incorporating enhanced CO2 transport is vital for optimizing performance in practical applications.