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.