A CO electrolyzer tandem cell system for CO-CO co-feed valorization in a Ni-N-C/Cu-catalyzed reaction cascade.

Coupled tandem electrolyzer concepts have been predicted to offer kinetic benefits to sluggish catalytic reactions thanks to their flexibility of reaction environments in each cell. Here we design, assemble, test, and analyze the first complete low-temperature, neutral-pH, cathode precious metal-free tandem CO electrolyzer cell chain. The tandem system couples an Ag-free CO-to-CO/CO electrolyzer (cell-1) to a CO/CO-to-C product electrolyzer (cell-2). Cell-1 and cell-2 incorporate selective Ni-N-C-based and Cu-based Gas Diffusion Cathodes, respectively, and operate at sustainable neutral pH conditions. Using our tandem cell system, we report strongly enhanced rates for the production of ethylene (by 50%) and alcohols (by 100%) and a sharply increased C energy efficiency (by 100%) at current densities of up to 700 mA cm compared to the single CO-to-C electrolyzer cell system approach. This study demonstrates that coupled tandem electrolyzer cell systems can offer kinetic and practical energetic benefits over single-cell designs for the production of value-added C chemicals and fuels directly from CO feeds without intermediate separation or purification.