Access to a larger operating window then allows more attention to be placed on modifying catalysts to specifically alter CO2 reduction product selectivity between higher-order products such as alkenes vs. alcohols and C2 vs C3 products. Finally, operating under an excess CO2 environment reduces the overpotential losses associated with transport limitations (sometimes called concentration polarizations). As a result, plots of voltage versus log(j) have been observed to remain linear even up to 300 mA/cm 2 , helping to remove one of the barriers to gauging intrinsic catalyst activity. While the exact implications of high current density catalyst testing will vary slightly with materials, we can assert that the local environment will differ greatly from the bulk electrolyte with a substantial chance of changing important surface kinetics and the observed catalytic activity. Tuning catalysts to optimize morphology or surface binding energies for low current density characterization may then risk optimizing the catalyst for the wrong environment unless higher current conditions can be appropriately mimicked.