Highly Selective and Active Electrochemical Reduction of CO₂ to CO on a Polymeric Co(II) Phthalocyanine@Graphitic Carbon Nitride Nanosheet–Carbon Nanotube Composite

The electrochemical reduction of CO 2 using intermittent renewable electricity is an attractive strategy for producing value-added fuels and chemicals, but until now, it has been greatly hindered by the shortage of high-performance electrocatalysts. In this study, we have demonstrated a type of molecular-catalyst-based hybrid material by the polymerization of cobalt phthalocyanine (CoPc) on a three-dimensional (3D) g-C 3 N 4 nanosheet–carbon nanotube support for the aqueous electrochemical reduction of CO 2 . The electrocatalytic results show that the obtained composite can selectively transform CO 2 to CO with considerable Faradaic efficiency (FE) of 95 ± 1.8%, a turnover frequency of 4.9 ± 0.2 s –1, and excellent long-term stability over 24 h at −0.8 V vs the reversible hydrogen electrode (RHE). In comparison to the analogous hybrid electrocatalysts prepared by the drop-drying or dip-coating method, the polymeric form of the molecular catalyst immobilized on 3D carbonaceous materials with an interconnected network enlarges the electrochemically active surface area and enhances the structural and operational robustness.