PTFE nanocoating on Cu nanoparticles through dry processing to enhance electrochemical conversion of CO2 towards multi-carbon products

Abstract

Polymer modified copper (Cu) catalysts have demonstrated an increased production of multi-carbon (C₂₊) products during the electrochemical CO₂ reduction reaction (CO₂RR). Herein, a solvent-free processing method has been developed to cover commercial Cu nanoparticles with a porous nanocoating of polytetrafluoroethylene (PTFE) that greatly improved the production of C₂₊ products. The PTFE coating created a large interfacial surface area that facilitated the transport of CO₂ to the solid–liquid–gas interface. The optimal catalyst achieved a faradaic efficiency of 78% for C₂₊ products and a notably large C₂₊ to C₁ product ratio of ∼13 at current densities ranging from 400 to 500 mA cm⁻². In comparison, catalysts prepared by a conventional solvent-based method only achieved a faradaic efficiency of 56% for C₂₊ products and a small C₂₊ to C₁ product ratio of ∼2 in the same current density range. Density functional theory (DFT) calculations suggested that the physisorbed PTFE coating on Cu catalysts plays a more significant role than the most frequently studied chemisorbed PTFE. The physisorbed PTFE is predicted to increase the binding energy of CO intermediates on Cu and lower the activation energy for C–C coupling steps, leading to significantly higher C₂₊ product selectivity of the Cu catalysts.