High‐Rate and Selective Conversion of Low‐Concentration Carbon Dioxide to Carbon Monoxide Using a Carbon Nanotube‐Supported Molecular Electrocatalyst

ABSTRACT Electrocatalytic CO 2 reduction reaction ( e ‐CO 2 RR), powered by renewable electricity, is a compelling strategy to valorize CO 2 into valuable chemicals and fuels. Herein, we report on MWCNT|CuPc‐CoPc‐modified gas‐diffusion electrodes (GDEs) featuring molecular‐level dispersion of cobalt phthalocyanine (CoPc) and copper phthalocyanine (CuPc) on the multi‐walled carbon nanotube (MWCNT) support. The introduction of CuPc effectively mitigates CoPc aggregation, enabling tunable loading and fractional accessibility of electrochemically active CoPc sites, alongside improved CO 2 adsorption capacity. Besides, the synergistic electronic interactions among CoPc, MWCNT, CuPc, and H 2 Pc, formed in situ via CuPc demetallization during electrolysis, optimized CO 2 affinity, as evidenced by density functional theory calculations. With these promising attributes, the MWCNT|CuPc‐CoPc‐modified GDE with optimized CuPc content exhibits promising e ‐CO 2 RR performance across a wide CO 2 concentration range (20%–98%). Notably, an efficient single‐pass conversion of CO 2 to CO is achieved, yielding a high CO yield of 65.7 ± 2.3% and an energy efficiency of 54.8 ± 1.9% using 20% CO 2 at an ampere‐level current (0.625 A). Furthermore, the developed electrode demonstrated robust stability, maintaining FE CO above 80.4% over 72‐h electrolysis under a simulated biogas atmosphere (40% CO 2 /60% CH 4 ). These findings underscore the strong promise of molecularly engineered catalyst systems for efficient and selective CO production from low‐concentration CO 2 emission sources.