Organic Cation Reconfiguration Enables Interfacial Network Structure for Enhanced CO2 Reduction

Abstract

The interfacial microenvironment within the electrical double layer plays a decisive role in governing electrochemical CO2 reduction reactions (CO2RR). Organic cations provide a highly tunable electrolyte platform enabling systematic control of interfacial structure and local electrochemical environments across both molecular-level descriptors and the collective configurations of multiple chains. By integrating molecular dynamics simulations with electrochemical measurements, we uncover the collective configuration as a decisive regulator of the interfacial microenvironment and CO2RR performance. Systematic variation of cation size and concentration reveals distinct collective configurations: single-molecule configuration, where cations remain individually dispersed, and interpenetrated-molecule configuration, where side-chain interpenetration forms a stable network. Compared to the single-molecule configuration, the interpenetrated-molecule configuration is found to be more effective in improving the interfacial electrochemical environment, underpinning enhanced Faradaic efficiency for CO. Notably, within each regime, CO2RR performance correlates with the overall interfacial microenvironment rather than any single property. These results elevate the multichain collective configuration to a key design dimension for organic cation electrolytes, providing molecular-level insight and clear guidance for the rational design of high-performance CO2RR systems.