Immobilized Azole Layer Tunes Interfacial Hydrogen Source for CO₂ Electroreduction in Strong Acid

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science

Background:

• Selective electrochemical carbon dioxide reduction reaction (CO2RR) in acidic media is challenging due to the competing hydrogen evolution reaction (HER).
• Understanding the role of different hydrogen sources (protons vs. water) in acidic electrolytes is crucial for improving CO2RR selectivity.

Purpose of the Study:

• To investigate the dynamic regulation of interfacial hydrogen sources in strong acid using an N-containing azole layer (phTA) immobilized on bismuth (Bi) catalysts.
• To elucidate the mechanism by which the phTA layer influences CO2RR selectivity by managing proton and water availability at the catalyst interface.

Main Methods:

• Immobilization of an N-containing azole layer (phTA) onto Bi catalysts.
• Electrochemical characterization and performance testing in strong acid (pH 0.4).
• Computational modeling to understand interfacial mechanisms and hydrogen source dynamics.

Main Results:

• The phTA layer dynamically regulates interfacial hydrogen sources, switching from proton relay at low potentials to water-based hydrogen evolution at higher potentials.
• This dynamic regulation suppresses HER and enhances CO2RR selectivity.
• Faradaic efficiency for formic acid (FEHCOOH) on Bi-phTA increased to 36% at -300 mA cm-2, significantly outperforming bare Bi (<10%).

Conclusions:

• The study demonstrates a novel strategy for controlling interfacial hydrogen species using a responsive organic layer.
• This approach effectively enhances CO2RR selectivity in strong acid by suppressing HER.
• Managing interfacial hydrogen sources is critical for advancing efficient CO2RR catalysis.