Dynamic Organic-Metal Interfaces Control CO2 Reduction Pathways via Water Regulated Thiol SAM Ordering

Area of Science:

• Electrochemistry
• Materials Science
• Surface Chemistry

Background:

• Precise control over interfacial microenvironments is crucial for enhancing selectivity in copper-catalyzed electrochemical CO2 reduction (CO2RR).
• Existing Cu-based catalysts often lack the fine-tuning needed to direct CO2RR towards specific products like methane or ethanol.
• Understanding the role of the organic-metal interface is key to designing more efficient catalysts.

Purpose of the Study:

• To engineer an organic-metal interface on Cu surfaces using self-assembled monolayers (SAMs).
• To investigate how this engineered interface modulates reaction pathways and selectivity in CO2RR.
• To establish a link between interfacial structure, dynamics, and product selectivity.

Main Methods:

• Assembly of 1-octanethiol SAMs on Cu surfaces.
• In situ infrared spectroscopy and hydrogen evolution kinetics measurements.
• Sum frequency generation spectroscopy, DFT, and AIMD simulations.

Main Results:

• The thiol-modified interface induced a selectivity shift from ethanol to methane.
• Potential-dependent regulation of *CO and *H intermediate kinetics was observed.
• SAM ordering correlated with a structural transition from disordered to ordered states.
• Disordered SAMs favored ethanol production, while ordered SAMs promoted methane production.

Conclusions:

• SAM ordering-regulated interfacial mobility is a key descriptor for CO2RR selectivity.
• Dynamic organic-metal interfaces offer a general strategy for tuning CO2RR pathways.
• This work provides insights into controlling catalytic selectivity by manipulating interfacial properties.