Noncovalent Construction of Hangman Cobalt Phthalocyanine for Enhanced Electrochemical Carbon Dioxide Reduction

The hangman structure plays a critical role in determining the reaction rates of molecular CO₂ electrocatalysis through constructing pendant functional groups in secondary coordination spheres of metal active sites. However, achieving hangman structures commonly requires complicated asymmetric synthesis. It is necessary to search for simple alternative strategies to develop hangman molecular electrocatalysis with realization of the concept of green chemistry. In this work, we report the synthesis of hangman molecular electrocatalysts based on the noncovalent π–π interaction between cobalt (Co) phthalocyanine nanotubes and 1-aminopyrene. It promoted the kinetics of interfacial inner and outer sphere electron transfer on the complex and chemisorption of *COOH and *CO species through interaction with both Co sites and pendant amine groups in a bridge geometry. The resultant Co sites afforded a very high turnover frequency of 4.37 s^–1 at an overpotential of 0.29 V for electrochemical CO₂ to CO conversion and thus afforded an industrial interest current density being steady at 350 mA cm^–2.