Metal-Modified Zr-MOFs with AIE Ligands for Boosting CO₂ Adsorption and Photoreduction.

Abstract

The design and synthesis of metal-organic frameworks (MOFs) with outstanding light-harvesting and photoexcitation for artificial photocatalytic CO₂ reduction is an attractive but challenging task. In this work, a novel aggregation-induced emission (AIE)-active ligand, tetraphenylpyrazine (PTTBPC) is proposed and utilized for the first time to construct a Zr-MOF photocatalyst via coordination with stable Zr-oxo clusters. Zr-MOF is featured by a scu topology with a two-fold interpenetrated framework, wherein the PTTBPC ligands enable strong light-harvesting and photoexcitation, while the Zr-oxo clusters facilitate CO₂ adsorption and activation, as well as offer potential sites for further metal modification. Consequently, the Zr-PTTBPC and its Co/Ni derivatives not only exhibit exceptional stability and high CO₂ adsorption capability (73 cm³ g^-1 at 273 K and 1 atm), but also demonstrate a CO production rate of up to 293.2 µmol g h^-1 under 420 nm LED light that can be reused for at least three cycles. With insights from charge-carrier dynamics and theoretical calculations, the underlying mechanism is revealed, confirming that the single-phase multi-component synergy is the key for the outstanding photocatalytic CO₂ reduction. This work showcases a brand-new type of MOF photocatalyst based on AIE ligands and their promising applications in photocatalytic C1 conversion.