Main challenges of continuous-flow CO2 electrolysis and strategies to overcome these. The third column lists the main operando methods expected to contribute.
| Challenges | Strategies to meet the challenge | Contribution of operando characterization |
|---|---|---|
| Improving energy efficiency5,6,59,77,78 | • Lowering anode and cathode potentials | • XASa, XPSa, Raman |
| ○ More active catalysts | ||
| ○ Alternative anode reactions | ||
| • Improving membrane conductivity | • Radiography, EISa | |
| Production of multi-carbon molecules4,79–81 | • Novel catalyst materials | • XAS, XPS, Raman |
| • Active site stabilization | ||
| • Optimization of local pH, CO2/CO concentration | • Local pH, Raman, IR | |
| • Mechanistic understanding of C–C coupling | • Raman, IR, EC-MSa | |
| • CO reduction | ||
| Stability improvement (>1000 h)22,59,82 | • Wet-proof GDEs | • Radiography |
| • Mitigating carbonate formation | • Local pH and ion concentration measurements | |
| • Improving membrane durability | • IR, Raman | |
| Efficient CO2 utilization23,83 | • Mitigation of CO2 and product crossover | • Radiography |
| • Local detection of CO2 and products | ||
| Scaling-up55,84 | • Scale-up or scale-out | • Local measurement of reactant/product concentrations, temperature, humidity (distribution) |
a
XAS: X-ray absorption spectroscopy, XPS: X-ray photoelectron spectroscopy, EIS: electrochemical impedance spectroscopy, EC-MS: electrochemical mass spectrometry.