For comparing the electrochemical surface area (ECSA) of the electrodes, the double-layer capacitance (Cdl) was used, as the ECSA is proportional to the Cdl. The Cdl was extracted from cyclic voltammetry (CV) curves, by measuring the current response in the non-faradaic potential region and relating it to the scan rate v. The experiments were conducted in 3 electrode geometry, with a Ag/AgCl reference and 0.5 M KHCO3 electrolyte. H2 and CO were determined online with a gas chromatograph (Shimadzu GC-2030) equipped with a ShinCarbon ST Micropacked column and a Dielectric-Barrier Discharge Ionization Detector (BID). The measured concentrations were used to calculate the Faradaic Efficiency of every product using the equation: