For CO2RR flow electrolysis, in order to get a good FEMeOH in the flow cell, CoPc/SWCNT with high CoPc loading catalysts was prepared using a CVD-type procedure according to our previous work . Then 5 mg catalysts mixed with 40 μL Nafion solution were deposited in 2 mL ethanol and sonicated for 1 h to form uniform ink and then drop-casting on 1×2.5 cm 2 GDL (Sigracet-28BC) (mass loading of the sample: 1 mg/cm 2 ). GDL with catalysts as a CO2RR cathode. A platinum and Ag/AgCl were used as the counter and reference electrodes, respectively. The cathode chamber and anode chamber were separated by Nafion-117 membrane (Fuel Cell Store). The CO2 gas flow with 10 sccm flow rate was conducted on the cathode side while 0.1 M KOH+3 M KCl and 1 M KOH electrolyte at 5 mL/min flow rate was circulated in cathode and anode chamber, respectively. The cathode electrolyte was collected in a flask with an ice bath for NMR testing.