Anionic Surfactant-Tuned Interfacial Water Reactivity Promoting Electrocatalytic CO₂ Reduction

Abstract

The effects of the electrical double layer (EDL), which pertain to the compositions and interactions among electrolyte species, significantly impact the catalytic process. There is a pressing need to investigate the role of electrolyte components and to deepen our understanding of EDL effects. In this study, we tune the water activity within a range of anionic surfactants featuring different functional groups to adjust H 2 evolution activity and CO 2 reduction selectivity. We demonstrate that these anionic surfactants are active in the local reaction environment under a cathodic potential. The enhanced selectivity of CO 2 to CO can be attributed to the robust interfacial hydrogenbonding network reformed by the anionic surfactants. This network diminishes the water dissociation activity and promotes the hydrogenation step in CO 2 reduction. Notably, the electrolyte incorporating anionic surfactants improves the CO 2 reduction performance, registering CO Faradaic efficiencies of 89.7% (RSO 3 − , SDS), 97.5% (RSO 4 − , SLS), 98.4% (RPO 4 2− , SMP), and 98.9% (RCOO − , SL) at −1.2 V versus RHE, thereby outperforming the blank KHCO 3 electrolyte (53.1%). This research underscores the crucial influence of anionic additives in the CO 2 RR.