Recovering Carbon Losses in CO2 Electrolysis using a Solid Electrolyte Reactor

The practical implementation of electrochemical CO2 reduction technology is greatly challenged by notable CO2 crossover to the anode side, where the crossed-over CO2 is mixed with O2, via interfacial carbonate formation in traditional CO2 electrolysers. Here we report a porous solid electrolyte reactor strategy to efficiently recover these carbon losses. By creating a permeable and ion-conducting sulfonated polymer electrolyte between cathode and anode as a buffer layer, the crossover carbonate can combine with protons generated from the anode to re-form CO2 gas for reuse without mixing with anodic O2. Using a silver nanowire catalyst for CO2 reduction to CO, we demonstrated up to 90% recovery of the crossover CO2 in an ultrahigh gas purity form (>99%), while delivering over 90% CO Faradaic efficiency under a 200 mA cm-2 current. A high continuous CO2 conversion efficiency of over 90% was achieved by recycling the recovered CO2 to the CO2 input stream.