Alkali-Enhanced Scalable Synthesis of Trinuclear Metal-Cluster Frameworks for Electrocatalytic CO₂ Conversion

Abstract

A novel method for synthesizing trinuclear metal–covalent organic frameworks (M₃-MCOFs) is proposed, using scaffold ligands that coordinate with metal ions and are stabilized by covalent bonds. The scaffold-ligand method (SLM) is optimized by introducing 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) to deprotonate pyrazole, forming SLM-D. This significantly enhances ligand-metal coordination and prevents metal ion reduction to nanoparticles, enabling efficient M₃-MCOFs preparation within five minutes. The method successfully yields nine types of M₃-MCOFs, including gram-scale Cu₃-H-MCOF, demonstrating the versatility and scalability of SLM-D for diverse structural designs. Cu₃-MCOFs exhibit excellent electrocatalytic CO₂ reduction (CO₂RR) performance, with a clear structure-activity correlation between the tri-copper clusters and CO₂RR efficiency. This approach offers a rapid, scalable, and effective route for the design and synthesis of M₃-MCOFs, paving the way for their broader application.