Design of titanium-oxide cluster-based metal-covalent organic frameworks for efficient photocatalytic CO₂ reduction

In response to the growing global energy requirements and escalating environmental issues, photocatalytic reduction of CO₂ has gained significant attention as an effective strategy for carbon resource reutilization and addressing climate change. In this study, a series of metal-covalent organic frameworks (MCOFs) incorporating titanium-oxide clusters (Ti6) were systematically designed and synthesized. By tuning the Ti6 incorporation ratio, MCOF-TDT was found to exhibit an outstanding CO generation rate with the highest formation rate of 168 μmol g^-1 h^-1. To further enhance the practical applicability of the photocatalyst, a MCOF layer was grown on a pre-synthesized Ti₆/PVDF substrate, successfully yielding MCOF-TDT/PVDF composite membranes, which achieved a CO generation rate of 78 μmol g^-1 h^-1. The incorporation of the PVDF substrate significantly improved the mechanical stability of the membrane while preserving much of its photocatalytic activity. This study presents a novel strategy for designing high-performance, stable photocatalytic materials and broadens the application scope of titanium-oxide cluster-based MCOFs in photocatalysis.