Redox‐Conjugated CoII‐Phthalocyanine–Phenazine Polymer as a Robust Catalyst for Efficient Electrochemical CO₂ Conversion

This work reports the synthesis and electropolymerization of 4‐aminophenoxy‐substituted Co II ‐phthalocyanine to prepare a phenazine (PNZ)‐bridged Co II ‐phthalocyanine polymer as a durable catalyst for heterogeneous electrochemical CO 2 reduction (ECO 2 R). At –1.19 V versus normal hydrogen electrode, the ECO 2 R under catalysis of the target polymer effectively produces CO with 94% faradaic efficiency (FE CO ), CO partial current density of 5.5 mA cm −2 , and turnover frequency of 1.1 s −1 over 2 h. Moreover, the polymeric system exhibits remarkably higher stability than the monomeric one by achieving average FE CO , current density and a turnover number of up to 93%, 7 mA cm −2 and 5.3 × 10 5 , respectively, along 120‐h electrolysis. Variable‐frequency square wave voltammetry indicates efficient electron transfer within polymeric bulk through the PNZ linkage, while in situ Raman spectroscopy reveals a higher proportion of electrochemically active Co I species in the polymer film than the monomer one. In addition, density functional theory calculations using the real‐space GPAW framework are conducted to investigate charge penetration in the extended π‐conjugated polymer network in comparison to that in the monomeric counterpart. These findings provide valuable insights for the rational design of the robust Co II ‐phthalocyanine‐based catalyst and contribute to the progress of an efficient CO 2 ‐to‐CO conversion.