Mixed‐metal Ionothermal Synthesis of Metallophthalocyanine Covalent Organic Frameworks for CO₂ Capture and Conversion

Abstract

Phthalocyanines (PCs) are intriguing building blocks owing to their stability, physicochemical and catalytic properties. Although PC‐based polymers have been reported before, many suffer from relatively low stability, crystallinity, and low surface areas. Utilizing a mixed‐metal salt ionothermal approach, we report the synthesis of a series of metallophthalocyanine‐based covalent organic frameworks (COFs) starting from 1,2,4,5‐tetracyanobenzene and 2,3,6,7‐tetracyanoanthracene to form the corresponding COFs named M‐pPPCs and M‐anPPCs, respectively. The obtained COFs followed the Irving–Williams series in their metal contents, surface areas, and pore volume and featured excellent CO₂ uptake capacities up to 7.6 mmol g⁻¹ at 273 K, 1.1 bar. We also investigated the growth of the Co‐pPPC and Co‐anPPC on a highly conductive carbon nanofiber and demonstrated their high catalytic activity in the electrochemical CO₂ reduction, which showed Faradaic efficiencies towards CO up to 74 % at −0.64 V vs. RHE.