Porous Copper-PTFE Hybrid Electrocatalyst for CO2 Reduction with High C2+ Selectivity

Abstract

The electrochemical CO₂ reduction reaction (CO₂RR) to ethylene (C₂H₄) is one of the most promising approaches to obtaining value-added C₂₊ hydrocarbons without net CO₂ emission. However, issues still to be solved for practical use include the improvement of Faradaic efficiency (FE) towards C₂H₄, electrode durability, and suppression of competitive hydrogen evolution reaction (HER). In this work, hydrophobic polymer, polytetrafluoroethylene (PTFE), added porous Cu electrocatalysts were firstly and successfully prepared on gas diffusion layer, and the significant enhancement of FEs toward C₂₊ products, especially C₂H₄, and durability were found. CO₂RR test in flow cell as a gas diffusion electrode (GDE) revealed that the GDE with porous Cu electrocatalysts showed higher FE(C₂H₄) to FE(CO) while significant HER and instability issues remained. Further modification by PTFE to form porous Cu-PTFE hybrid structure significantly decreased FE(H₂) to 11.6 % in minimum, enhanced FE(C₂H₄) to 51.1 % in maximum and raised durable CO₂RR for over 24 hours under current density of −300 mA cm⁻². PTFE addition should form a secured pathway for gas species, including both reactant and product which was beneficial for durable and selective C₂H₄ production. This work highlights chemical engineering aspects of CO₂RR including the transportation of reactants and products.