For NiPc/CNT CO2RR measurement, 2 mg of catalyst in 1 mL of ethanol with 20 μL 5 wt.% Nafion solution and sonicated 1 h to form a homogeneous catalyst ink. All the catalysts were dropcast onto carbon paper (Toray, TGP-H-060, Fuel Cell Store) (diameter of 0.5 inch) with a 0.4 mg/cm 2 loading. The electrochemical performance was carried out in a customized threecompartment cell, as previously reported . A platinum foil and Ag/AgCl leak-free reference (LF-2, Innovative Instrument Inc.) were used as the counter and reference electrode, respectively. The working electrode was separated from the counter electrode by the Nafion-117 membrane.