In the CO2 recycling tests, a labcustomized electrochemical cell with three compartments (for the working, reference, and counter electrodes) was used. Each cathodic and anodic compartment contained 6 mL of 1 M KOH electrolyte. The CO2 reduction reaction was performed at various potentials in CO2saturated 1 M KOH (pH = 13.8, measured with an Accumet AB15 pH meter) for 60 minutes, with the electrolyte remaining static (no peristaltic pump was used). After electrolysis, a 1 mL gas sample was taken through a septum port using a gas-tight syringe and injected into a gas chromatograph (GC) (Shimadzu 2014) to quantify the amounts of CO, H2, and hydrocarbons.