Electroplated copper shows CO2 ER activity in 0.01 M KHCO3 saturated with CO2 at EWE < -0.3 V vs. SHE' (Figure ). The ITO electrode is inert at this range of electrochemical potentials, which means that the copper particles are responsible for this activity (Figure ). On the contrary, copper only exhibited measurable electrochemical activity at EWE < -0.6 V in 0.01 M K2SO4 saturated with N2. K2SO4 saturated with N2 is CO2-free, which suggests that the detected activity is ascribed to the hydrogen evolution reaction (HER). The electrochemical activity of copper in 0.01 M KHCO3 saturated with N2 is equivalent to that observed in 0.01 M K2SO4 saturated with N2. That indicates that the HER is also the predominant reaction when N2 is bubbled into a 0.01 M KHCO3 electrolyte.