A second important property of the local reaction environment at commercial-relevant current densities is access to excess CO2. While we have imposed a current density of 200 mA/cm 2 as a threshold to reach, from Fig. we can see that additional unreacted CO2 surrounding the catalyst provides the capacity for even higher current densities. An increased CO2 concentration, even at elevated current densities, helps to kinetically ensure that CO2 rather than protons are able to populate the reaction surface. More importantly, the reaction will not be hindered by a deficit of CO2, even at higher local pH conditions. While single-carbon CO2 reduction products such as CO, HCOOH and CH4 can reach relatively high selectivities even at lower current densities in an H-cell configuration, the highest Faradaic efficiencies reported for multi-carbon products typically appear at current densities where CO2 is almost depleted. This is in part due to the necessity for multi-carbon products to follow from *CO (Fig. ) and C-C coupling which requires both sufficient potentials and current densities. Testing novel catalysts at elevated current densities with less CO2 limitations would allow the surface coverage of the *CO reaction intermediate to be maximized over a wider current and potential range without being kinetically-limited by CO2 availability. This is in contrast to current H-cell environments where peak C2 selectivities are often observed only at singular operating conditions (i.e. at a specific potential, current density and pH).