Self-Cleaning CO2 Reduction Systems: Unsteady Electrochemical Forcing Enables Stability

The electrochemical conversion of CO 2 produces valuable chemicals and fuels. However, operating at high reaction rates produces locally alkaline conditions that convert reactant CO 2 into cell-damaging carbonate salts. These salts precipitate in the porous cathode structure, block CO 2 transport, reduce reaction efficiency, and render CO 2 electrolysis inherently unstable. We propose a self-cleaning CO 2 reduction strategy with short, periodic reductions in applied voltage, which avoids saturation and prevents carbonate salt formation. We demonstrate this approach in a membrane electrode assembly (MEA) with silver and copper catalysts, on carbon and polytetrafluoroethylene (PTFE)-based gas diffusion electrodes, respectively. When operated continuously, the C 2 selectivity of the copper–PTFE system started to decline rapidly after only ∼10 h. With the self-cleaning strategy, the same electrode operated for 157 h (236 h total duration), maintaining 80% C 2 product selectivity and 138 mA cm –2 of C 2 partial current density, at a cost of <1% additional energy input.