An extremely high applied potential would over-reduce the Pc ligand, resulting in deactivation via demetallation . To probe for demetallation, we measured the UV-vis absorption during long-term stability tests for the H-cell, the CO2RR flow cell, and the CORR flow cell (Supplementary Fig. ). Compared to the pristine UV-vis spectrum (Supplementary Fig. ), post-electrolysis CoPc/SWCNT displayed no new absorption peaks, indicating no demetallation.