Polyoxometalates coupled covalent organic frameworks as highly active photothermal nanoreactor for CO₂ cycloaddition

Covalent organic frameworks (COFs)-based nanoreactors have attracted broad interest in many fields due to their void-confinement effects. However, the inherent drawback of conventional nanoreactors is the lack of internal active sites, which limits their widespread utilization. Herein, we report the construction of hierarchical COF (EB-TFP) nanoreactor with pre-synthesized polyoxometalates (POM, PV₂W₁₀) clusters encapsulated inside of COF (POM@COF). PV₂W₁₀@ EB-TFP anchors nucleophilic-group (Br^- ions) and PV₂W₁₀ anion cluster ([PV₂W₁₀O₄₀]^5-) within the COF framework via electrostatic interactions, which not only simplifies the reaction system but also enhances catalytic efficiency. The reaction performance of the PV₂W₁₀@ EB-TFP nanoreactor can be tuned to achieve excellent catalytic activity in CO₂ cycloaddition reaction (CCR) for ~97.63% conversion and ~100% selectivity under visible light irradiation. A mechanistic study based on density functional theory (DFT) calculations and in-situ characterization was also carried out. In summary, we have reported a method for achieving the uniform dispersion of POM single clusters into COF nanoreactor, demonstrating the potential of POM@COF nanoreactor for synergistic photothermal catalytic CO₂ cycloaddition.