Evolution of Triple-Phase interface for enhanced electrochemical CO2 reduction

Selective electrochemical CO2 reduction reaction (CO2RR) requires efficient triple-phase contact of CO2 molecules, electrolyte and active sites of electrocatalyst. To achieve this, studies have sought to use surface modifications to electrodes. However, the stability of these modifications and their effects on the intrinsic properties of electrodes are rarely discussed. Here, hydrophobic treatment of 1-octadecanethiol modification to a copper dendrite electrode was taken as a benchmark to investigate the evolution of the electrode surface and corresponding CO2RR performance after modifications. We show that the initial hydrophobic surface (HB-Cu) eventually transformed into a stable triple-phase interface (TP-Cu), ascribed to the formation of stable copper thiolate and the generation of crevices from alkane sulfonate dissolution. Surprisingly, this structural evolution leads to lower resistance of charge transfer and more sufficient exposure of active sites, enabling efficient triple phase contact. As a result, TP-Cu achieved a near 4-fold enhancement of current density and a more than 2-fold reduction of H-2 production compared to HB-Cu. Compared to previous studies, we have demonstrated extra power of the surface modification strategy to design triple-phase electrode interface, facilitating selective and efficient electrochemical CO2 reduction.

Automated summary

This study investigates the evolution of electrode surface and CO2RR performance after surface modifications. The results show that the modified copper electrode forms a stable triple-phase interface, resulting in enhanced current density and reduced H2 production.