Insights into the hydrophobic surface promoting electrochemical CO2 reduction to ethylene

Abstract

The electrochemical CO2 reduction reaction (CO2RR) converts CO2 to value-added C2+ chemical products, offering a feasible pathway for electric energy storage and the carbon cycle. An overarching challenge is to find a highly active catalyst to achieve high-selectivity hydrocarbon production. Herein, by coating Cu-I with a hydrophobic polymer polytetrafluoroethylene (PTFE), the hydrophobic microenvironment was constructed for the efficient CO2RR. The Faradaic efficiency of C2H4 reached 70.2% at − 1.4 V versus the reversible hydrogen electrode (RHE) over the Cu-I/PTFE electrode, which was about 1.4 times higher than the Cu-I electrode. The accelerated diffusion of gas at the interface increases the CO2 local concentration for the electrolysis. In situ EPR studies show that the hydrophobic Cu-I/PTFE electrode provides enhanced production of the hydroxyl (·OH) radicals in the HCO3− aqueous solution. The ·OH radicals can stabilize Cu+ species during the electrocatalysis process. In situ surface-enhanced Raman spectroscopy (SERS) reveals that the CO* intermediate is adsorbed in the Cu+ sites, which facilitates C-C coupling. Results reported in this work highlight the effect of the introduction of hydrophobic structures over Copper-based electrocatalyst on the selective formation of C2+ products.