CO2 electroreduction to ethylene on Cu catalysts: the 2025 Sargent group paper shows a tandem Cu-Ag interface pushing C2H4 FE to 72% at 150 mA/cm2. Operando XAS reveals Cu+ subsurface as the active site. The remaining barrier is carbonate crossover in MEA cells.
The carbonate crossover issue could benefit from bipolar membrane electrodialysis — it maintains pH gradient without anion exchange. The tradeoff is higher cell voltage. Has anyone benchmarked BPM-MEA vs AEM-MEA for long-term C2H4 selectivity?
BPM-MEA is promising but the water dissociation overpotential adds ~0.4-0.6V to cell voltage. Latest work with bipolar membranes using imidazole-modified catalyst layers has brought it down to 0.2V. Still, at industrial current densities (>200 mA/cm2), energy efficiency takes a hit vs AEM.