CO2-affinitive surface of metal/Nafion attributable to selective polarization for superior CO2RR

Abstract

The CO₂ reduction reaction (CO₂RR) is considered a promising process that can compensate for CO₂ emissions by converting them into value-added chemicals. In the preparation of the CO₂RR catalytic electrode, Nafion is a common binder, but its effect in the catalytic process is usually ignored. Herein, we proposed the bifunctionality of Nafion in the CO₂RR based on its molecular structure and successfully developed a CO₂-affinitive surface of micro-Ag/Nafion by controlling the content of Nafion, which exhibited a superior CO faradaic efficiency (FE_CO) of 95.07% at −0.9 V (vs. RHE). This excellent FE_CO and a partial current density (j_CO) twice that of CO in the flow-cell proved its industrial prospects. Its splendid selectivity for the CO₂RR was attributed to the selective polarization of CO₂ molecules on Nafion, which resulted in a 6.8 times higher adsorption energy (E_ads) of CO₂ than that of H₂O. Therefore, the CO₂RR gained an advantage in the competitive reaction. Nafion was recognized as a favorable transporter for CO₂ on the surface of the metal catalyst. Our work describes the bifunctional role of Nafion in the CO₂RR electrode, and it will contribute to optimize the design of the metal/Nafion catalytic material for the CO₂RR.