Scalability and stability in CO2 reduction via tomography-guided system design
Colin P. O’Brien, David W. McLaughlin, Thomas Böhm, Yurou Celine Xiao, Jonathan P. Edwards, Christine M. Gabardo, Markus Bierling, Joshua Wicks, Armin Sedighian Rasouli, Jehad Abed, Daniel Young, Cao‐Thang Dinh, Edward H. Sargent, Simon Thiele, David Sinton
Abstract
Electrocatalytic CO2 reduction offers a means to produce value-added multi-carbon products and mitigate CO2 emissions. However, the stability of CO2 electrolyzers for C2+ products has not exceeded 200 h—well below that of CO- and H2-producing electrolyzers—and the most stable systems employ low-conductivity substrates incompatible with scale. Current gas diffusion electrodes (GDEs) become filled with salt precipitate and electrolyte, which limits CO2 availability at the catalyst beyond 30 h. We develop a GDE architecture that is resistant to flooding and maintains stable performance for >400 h. Using a combination of focused ion beam scanning electron microscopy, micro-computed tomography, and a purpose-built array tomography technique, we determine that the enhanced stability is due to a percolating network of polytetrafluoroethylene in the microporous layer that retains hydrophobicity. We scale this approach in an 800 cm2 cell and an 8,000 cm2 stack and transfer >108 C, the largest reported CO2 electrolysis demonstration.