One of the advantages of mass transport model is the ease of observing how varying concentration of reactants such as CO2 and H + /local pH affect product selectivity of the reaction. We observe the decline in CO2 concentration in Fig. is subtle until -1.1 V, beyond which there is a rise in the generation of methane, ethylene, ethanol and bicarbonate ion (𝐶𝑂 3 2-) However, methane is produced in higher quantities due to the lower carbon content required.