Polymer Modification Strategy to Modulate Reaction Microenvironment for Enhanced CO₂ Electroreduction to Ethylene

Modulation of the microenvironment on the electrode surface is one of the effective means to improve the efficiency of electrocatalytic carbon dioxide reduction (eCO₂RR). To achieve high conversion rates, the phase boundary at the electrode surface should be finely controlled to overcome the limitation of CO₂ solubility in the aqueous electrolyte. Herein, we developed a simple and efficient method to structure electrocatalyst with a superhydrophobic surface microenvironment by one-step co-electrodeposition of Cu and polytetrafluoroethylene (PTFE) on carbon paper. The super-hydrophobic Cu-based electrode displayed a high ethylene (C₂H₄) selectivity with a Faraday efficiency (FE) of 67.3 % at −1.25 V vs. reversible hydrogen electrode (RHE) in an H-type cell, which is 2.5 times higher than a regular Cu electrode without PTFE. By using PTFE as a surface modifier, the activity of eCO₂RR is enhanced and water (proton) adsorption is inhibited. This strategy has the potential to be applied to other gas-conversion electrocatalysts.