Exploring the impact of Nafion modifier on electrocatalytic CO2 reduction over Cu catalyst

Nafion as a universal polymer ionomer was widely applied for nanocatalysts electrode preparation. However, the effect of Nafion on electrocatalytic performance was often overlooked, especially for CO₂ electrolysis. Herein, the key roles of Nafion for CO₂RR were systematically studied on Cu nanoparticles (NPs) electrocatalyst. We found that Nafion modifier not only inhibit hydrogen evolution reaction (HER) by decreasing the accessibility of H₂O from electrolyte to Cu NPs, and increase the CO₂ concentration at electrocatalyst interface for enhancing the CO₂ mass transfer process, but also activate CO₂ molecule by Lewis acid-base interaction between Nafion and CO₂ to accelerate the formation of *CO, which favor of C–C coupling for boosting C₂ product generation. Owing to these features, the HER selectivity was suppressed from 40.6% to 16.8% on optimal Cu@Nafion electrode at −1.2 V versus reversible hydrogen electrode (RHE), and as high as 73.5% faradaic efficiencies (FEs) of C₂ products were achieved at the same applied potential, which was 2.6 times higher than that on bare Cu electrode (∼28.3%). In addition, Nafion also contributed to the long-term stability by hinder Cu NPs morphology reconstruction. Thus, this work provides insights into the impact of Nafion on electrocatalytic CO₂RR performance.