Our results suggest that at low pH the well-known copper degradation observed during CO2 ER is a corrosion process that depends on the presence of CO2 in solution, even if the CO2 ER reaction is not being driven. This contrasts with previous studies that report copper fragmentation during CO2 ER induced by applied electrochemical potentials . Similar to other metals of the ninth column and the top row of the transition metals, copper too can form a variety of CO2-containing charged complexes which can be mobilized into aqueous media (solubilization) . Indeed, this is a risk associated with CO2 injection into underground aquifers for carbon sequestration purposes, where Cu and other metals can form carbonates and become mobilized in solution . Likewise, the degradation of copper when CO2 is present in solution, whether CO2 ER is happening or not, is also consistent with copper corrosion caused by acid rain, where CO2 acts as a corrosion agent . The role of CO2 in the corrosion of copper is supported by the lack of observed degradation when KHCO3 is saturated with N2 instead of CO2. CO2 can interact directly with Cu surfaces, via O and OH to form CO3 and HCO3 species that may facilitate the Cu dissolution process . This is supported by the oxidized copper signature shown in the EELS results for Cu particles that undergo degradation. Both our experimental results and our DFT calculations suggest that surface complexed copper is prone to be pulled into solution in the presence of CO2, thus supporting a corrosion driven degradation. This supports our conjecture that, as opposed to CO2, HCO3 -by itself does not have an active role in the Cu corrosion process.