Graphdiyne-supported metal alloy at the atomic level for the efficient cycloaddition reaction of CO2

Abstract

Controlling the local coordination environment of metal active centers is important in tailoring catalytic performance and clarifying structure–activity relationships, and is a fundamental principle for developing advanced atomic-scale catalytic systems. In this work, we report a stereo-confinement strategy to regulate the arrangement and composition of metal atom sites by using Ir and Cu atoms co-fixed in pairs on graphdiyne (GDY). The coordinated Cl in the as-synthesized IrCu–Cl/GDY can be readily replaced by Br or I via a facile ligand-exchange process, yielding IrCu–Br/GDY and IrCu–I/GDY, respectively. Theoretical analysis reveals the gradual decrease in the charge distribution between Ir atoms and the coordinating halogen along the series Cl → Br → I. Mechanistic studies indicate that the iodide ligand effectively participates in CO₂ insertion and subsequent ring-closing steps, significantly lowering the reaction energy barriers and thereby enhancing the overall catalytic activity for the cycloaddition reaction. Remarkably, the catalytic cycloaddition activity of CO₂ and styrene oxide increases significantly as Cl is exchanged with I, achieving the best cycloaddition performance with 95% conversion and 99% selectivity.