3D-Printable Fluoropolymer Gas Diffusion Layers for CO₂ Electroreduction

The electrosynthesis of value-added multicarbon products from CO₂ is a promising strategy to shift chemical production away from fossil fuels. Particularly important is the rational design of gas diffusion electrode (GDE) assemblies to react selectively, at scale, and at high rates. However, the understanding of the gas diffusion layer (GDL) in these assemblies is limited for the CO₂ reduction reaction (CO₂ RR): particularly important, but incompletely understood, is how the GDL modulates product distributions of catalysts operating in high current density regimes > 300 mA cm^-2 . Here, 3D-printable fluoropolymer GDLs with tunable microporosity and structure are reported and probe the effects of permeance, microstructural porosity, macrostructure, and surface morphology. Under a given choice of applied electrochemical potential and electrolyte, a 100× increase in the C₂ H₄ :CO ratio due to GDL surface morphology design over a homogeneously porous equivalent and a 1.8× increase in the C₂ H₄ partial current density due to a pyramidal macrostructure are observed. These findings offer routes to improve CO₂ RR GDEs as a platform for 3D catalyst design.