Highly selective and productive reduction of carbon dioxide to multicarbon products via in situ CO management using segmented tandem electrodes
Electrochemical CO 2 reduction provides a promising route to the sustainable generation of valuable chemicals and fuels. Tandem catalysts enable sequential CO 2 -to-CO and CO-to-multicarbon (C 2+ ) product conversions on complementary active sites, to produce high C 2+ Faradaic efficiency (FE). Unfortunately, previous tandem catalysts exhibit poor management of CO intermediates, which diminishes C 2+ FE. Here, we design segmented gas-diffusion electrodes (s-GDEs) in which a CO-selective catalyst layer (CL) segment at the inlet prolongs CO residence time in the subsequent C 2+ -selective segment, enhancing conversion. This phenomenon enables increases in both the CO utilization and C 2+ current density for a Cu/Ag s-GDE compared to pure Cu, by increasing the *CO coverage within the Cu CL. Lastly, we develop a Cu/Fe-N-C s-GDE with 90% C 2+ FE at C 2+ partial current density (j C2+ ) exceeding 1 A cm -2 . These results prove the importance of transport and establish design principles to improve C 2+ FE and j C2+ in tandem CO 2 reduction.