Direct Synthesis of Topology-Controlled BODIPY and CO2-Based Zirconium Metal-Organic Frameworks for Efficient Photocatalytic CO2 Reduction.

Boron dipyrromethene (BODIPY)-based zirconium metal-organic frameworks (Zr-MOFs) possess strong light-harvesting capabilities and great potential for artificial photosynthesis without the use of sacrificial reagents. However, their direct preparation has not yet been achieved due to challenges in synthesizing suitable ligands. Herein, we reported the first successful direct synthesis of BODIPY-based Zr-MOFs, utilizing CO2 as a feedstock. By controlling synthetic conditions, we successfully obtained two distinct Zr-MOFs. The first, CO2-Zr6-DEPB, exhibits a face-centered cubic (fcu) topology based on a Zr6(μ3-O)4(μ3-OH)4 node, while the second, CO2-Zr12-DEPB, features a hexagonal closed packed (hcp) topology, structured around a Zr12(μ3-O)8(μ3-OH)8(μ2-OH)6 node. Both MOFs demonstrated excellent crystallinity, as verified through powder X-ray diffraction and high-resolution transmission electron microscopy analyses. These MOF catalysts displayed suitable photocatalytic redox potentials for the reduction of CO2 to CO using H2O as the electron donor in the absence of co-catalyst or toxic sacrificial reagent. Under light irradiation, CO2-Zr12-DEPB and CO2-Zr6-DEPB offered high CO yields of 16.72 and 13.91 μmol g-1 h-1, respectively, with nearly 100 % selectivity. CO2 uptake and photoelectrochemical experiments revealed key insights into the mechanisms driving the different catalytic activities of the two MOFs. These BODIPY and CO2-based, light-responsive Zr-MOFs represent a promising platform for the development of efficient photocatalysts.