Further, it has been noted in literature that formation of ethylene on Cu(100) is pH-independent on the SHE scale but depends on local pH on the RHE scale. Using highly concentrated electrolytes (such as KOH) with elevated pH has been demonstrated to significantly shift the onset voltages of ethylene and related products towards more positive values. Consequently, production of ethylene through the low voltage pathway can occur at voltage between -0.3 and -0.8 V when a higher pH ( 13) is used. However, our study employs a less alkaline electrolyte (0.1 KHCO3) with a bulk pH of 6.8 with a low catalyst specific surface area. In the GDE mass transport model, there is a steep rise in local pH with corresponding increase in applied voltages, see Fig. . The local pH within the porous catalytic bed is therefore observed to increase to 12.5 at an applied voltage of -1.25 V due to production of OH -ions from the electrochemical reduction of CO2. As a result, the higher local pH required to activate formation ethylene in the low voltage C2 pathway is only achieved in the high voltage region.