(726e) Porous Metallic Membranes As High-Performance Cathodes for CO2 Reduction

Combining the electrochemical reduction of CO₂ (eCO₂RR) with carbon-neutral energy sources creates groundbreaking possibilities for using CO₂ as a raw material for the sustainable production of fuels and chemicals. In particular, its efficient reduction to carbon monoxide and to ethylene at high current densities would provide key building blocks in a future fossil fuel-free chemical industry.

Recent reports using gas diffusion electrodes (GDEs) have demonstrated the viability of carrying out the eCO₂RR at industrially relevant reaction rates, but more insights into the influence of cell design and electrode structure are needed to guide further upscaling efforts. In this presentation, we will discuss our recent work using carbon-free metallic membranes as cathodes for CO₂ reduction in a vapor-fed electrolytic device. When combined with a Sustainion anion exchange membrane (AEM) in a membrane electrode assembly (MEA), porous silver membranes can sustain high rates of CO₂ reduction to CO (ca. 250 mA/cm² at a cell voltage of 3.1 V) with negligible hydrogen evolution. Furthermore, the homogeneous structure of these membranes provides an ideal platform to study the influence of the electrode pore network on the performance of CO₂ reduction electrolyzers. We will discuss the eCO₂RR performance of porous copper GDEs and describe how the morphology of the electrodes and the availability of different catalytic sites can be tuned via the synthetic procedure. In addition, we will show how the analysis of both cathodic and anodic outlet flows is key for a more complete understanding of CO₂ reduction at high current densities in electrolytic devices, and experimental strategies in this regard will be presented.