Effect of Ionomer Content and Ag/C Catalyst Surface Area on the Performance of CO2 Electrolysis to CO

Carbon-supported silver catalysts have proven high activity and durability in the electrochemical reduction of CO2 to CO. This work investigates the impact of cathode catalyst layer composition on performance by varying the ionomer content and Ag/C catalysts with differing BET surface areas (33–455 m2 g–1). For optimal performance, there is a positive correlation between optimal ionomer binder content and catalyst surface area: 5 wt % PiperION for Ag/CSuper P, 15 wt % PiperION for Ag/CVulcan, and 25 wt % PiperION for Ag/CKetjen. The top-performing cells exhibited remarkably high CO faradaic efficiencies of 93% for 15 wt % Ag/CVulcan, 91% for 5 wt % Piperion Ag/CSuper P, and 90% for 25 wt % Piperion Ag/CKetjen (all at 400 mA cm–2 with 0.01 M CsOH as anolyte). Long-term measurements at 300 mA cm–2 over 100 h revealed the lowest FECO loss for Ag/CVulcan, decreasing from 93 to 87%, followed by Ag/CSuper P (91–79%) and Ag/CKetjen (90–63%).