One of the main challenges towards achieving high-efficiency solar-fuel generators performing CO₂ reduction are the mass-transport limitations in traditional aqueous systems due to CO₂ interactions/solubility and boundary-layer thickness. To circumvent these issues, gas-diffusion electrodes (GDEs) are considered wherein the CO₂ is fed in a vapor form into a porous electrode. In this talk, we will explore the various tradeoffs endemic in GDE architectures. This is accomplished through multiphysics modeling of the cells including breakdowns of the various limiting phenomena. In addition, experimental data on the GDEs for CO2 reduction will be presented using both Ag and Cu-based catalysts. Key is understanding the potential distributions with the GDE and how this along with the observed higher current densities impact product selectivity with Cu-based catalysts. Finally, comments will be made concerning the possibilities of light inclusion in GDEs to enable solar CO₂ reduction as well as the benefits of GDEs that extend beyond higher current-density operation including unprecedented control of the local environment compared to traditional, aqueous planar designs.

Acknowledgements

The material is based on work performed at the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, through the Office of Science of the U.S. Department of Energy under award no. DE-SC0004993