Electrochemical reduction of CO2 emitted from point sources (e.g., cement production, separation from natural gas, iron and aluminum ore smelting, and fermentation of sugars) using electricity from renewable resources (e.g., wind and solar) offers a means for recapturing its carbon content. Moreover, if the CO2 can be taken from the atmosphere and converted electrochemically to chemicals and fuels, one could envision a closed carbon cycle. In order to produce desired products with high rates and selectivity, it is important to understand how to design electrochemical cells that enable achievement of these objectives. A key element in pursuit of this goal is accurate representation of the rates individual product formation rates and their dependence on reactant concentration, pH, and cathode potential.