In Situ Observation of Triple-Phase Interface during Electrocatalytic CO₂ Reduction

Area of Science:

• Electrochemistry
• Catalysis
• Spectroscopy

Background:

• The triple-phase interface (solid-liquid-gas) is crucial for CO2 electro-reduction reaction (CO2RR) performance.
• Observing this interface in situ is difficult due to the complex reaction environment.

Purpose of the Study:

• To develop a method for unobstructed in situ observation of the CO2RR triple-phase interface.
• To investigate the influence of the triple-phase interface microenvironment on CO2RR selectivity.
• To elucidate the reaction mechanisms at the triple-phase interface.

Main Methods:

• Development of a catalyst-integrated gas diffusion electrode (GDE) with a biomimetic hydrophobic structure.
• In situ Raman spectroscopy for microscale observations.
• In situ 3D Raman tomography for spatial visualization.
• Computational modeling.

Main Results:

• The developed GDE enabled unobstructed in situ Raman observation of the triple-phase interface.
• The triple-phase interface microenvironment significantly enhanced multicarbon (C2+) selectivity.
• In situ 3D Raman tomography precisely visualized the triple-phase interface distribution.
• High local pH and rapid CO2 mass transfer were identified at the interface.

Conclusions:

• The catalyst-integrated GDE is effective for in situ studying the CO2RR triple-phase interface.
• Understanding the interface microenvironment is key to improving CO2RR catalyst design and performance.
• The study provides fundamental insights into CO2RR mechanisms for enhanced C2+ production.