To gain insights into how CO2 contributes to the degradation of copper under CO2 ER conditions, we tested the susceptibility to degradation at potentials more anodic than the onset for CO2 ER. This effectively removes CO2 reduction products as possible causes for Cu degradation. Copper degradation did occur in KHCO3 saturated with CO2 at EWE = 0 V vs SHE' (Figure and Figure ). This electrochemical potential is insufficient to drive CO2 ER, which indicates that copper degradation is enabled even in the absence of CO2 ER and its products. Interestingly, once again, at EWE = 0 V copper degradation was only observed if CO2 was present in the electrolyte, with the phenomena visibly being similar to that observed at EWE = -0.8 V. An identical result was also observed for bulk copper, prepared through e-beam deposition. Even though this sample contained a bulk copper electrode, corrosion was still visibly evident after 15 minutes when KHCO3 was saturated with CO2 (Figure (panels g-h)).