Tailoring Hydrogenation Pathway to Redirect CO₂ Electroreduction From Ethylene to Ethanol

Area of Science:

• Electrochemistry
• Catalysis
• Surface Science

Background:

• Electrochemical reduction of carbon dioxide (CO2) to ethanol faces challenges due to competing ethylene formation.
• Existing strategies focus on catalyst electronic structure and CO coverage, neglecting competitive hydrogenation pathways.

Purpose of the Study:

• To investigate the role of competitive hydrogenation mechanisms in CO2 reduction selectivity.
• To develop a strategy for enhancing ethanol selectivity by modulating interfacial hydrogen-bond networks.

Main Methods:

• Hierarchically assembled BPEI/PT interfaces were used to dynamically modulate hydrogenation pathways.
• In situ Raman spectroscopy was employed to capture reaction intermediates.
• Experimental and theoretical studies were combined to establish quantitative relationships between hydrogen-bond strength and selectivity.

Main Results:

• Ethanol selectivity was found to be governed by the balance between Langmuir-Hinshelwood (surface *H) and Eley-Rideal (solvent H) hydrogenation mechanisms.
• Reconstruction of interfacial hydrogen-bond networks suppressed the Eley-Rideal pathway, enhancing ethanol selectivity.
• Achieved 38.7% ethanol Faradaic efficiency (FE) on CuO-derived catalysts and 53% FE on CuAg systems at high current densities.

Conclusions:

• Controlling competitive hydrogenation pathways through interfacial engineering offers an independent parameter for steering CO2 reduction selectivity.
• This approach significantly improves ethanol production efficiency in electrochemical CO2 reduction.
• The findings provide a new paradigm for designing catalysts for selective CO2 conversion.