Nanoclusters Embedded in Phthalocyanine Covalent Organic Polymer Enhance the Cycloaddition Reaction of Carbon Dioxide.

Abstract

Photocatalytic cycloaddition of carbon dioxide and epoxides under mild conditions is important for green chemistry, while metal clusters loaded on a variety of carriers are widely used in energy and biology. However, under long-term illumination, the light stability of metal clusters at the carrier interface is poor, which usually leads to the loss of catalytic performance. Covalent organic polymers (COPs) with periodic and ultrasmall pore structures are ideal carriers for dispersing and stabilizing metal clusters. Through a simple nitrogen purge process, embedding Mn2Dy2 clusters on a hydroxy-containing COP was successfully achieved, which makes it an effective photocatalyst for CO₂ cycloaddition. By introducing adjacent hydroxyl and imine bonds in the COP unit, periodic dispersed adsorption sites of metal clusters were constructed, generating a large number of active photogenerated electrons. The photoelectric measurement results indicate that the catalyst is excellent, with good charge separation efficiency. The Mn2Dy2 clusters widely presented on COP expose large active surfaces, greatly promoting electron transfer. The highest cycloaddition conversion rate at room temperature and normal pressure is 99%, and the TON value is 2352. This is of great significance for the study of novel photocatalytic cycloaddition of carbon dioxide.