Encapsulating perovskite quantum dots into 3D COF for visible light-driven CO2 reduction

Lead halide perovskite quantum dots (LHP QDs) have been revealed to possess great potential in photocatalytic applications including CO₂ reduction, which however suffer from poor stability. Herein, a high crystalline hydrazine-linked three-dimensional (3D) covalent organic framework, USTB-17, was fabricated from the reaction between 12-connected building block and 4-connected 3,5,7-tetrakis(4-aldophenyl)-adamantane. Post-modification with Ni²⁺ affords the metallic framework USTB-17(Ni) followed by sequential deposition of the CH₃NH₂PbI₃ (MAPbI₃) perovskite QDs into its pores, generating the USTB-17(Ni)@MAPbI₃ composite. Powder X-ray diffraction analysis together with theoretical simulations and transmission electron microscopy discloses the crystalline nature of USTB-17, USTB-17(Ni), and USTB-17(Ni)@MAPbI₃ with an unprecedented non-interpenetrated hpt topology. The close contact of QDs inside the COF pores with the Ni catalytic site locating at the pore surface of COF allows a rapid transfer of the photogenerated electrons in QDs to the Ni catalytic sites, enhancing the photocatalytic activity for CO₂ reduction. This endows USTB-17(Ni)@MAPbI₃ with efficient photocatalysis performance for photocatalytic CO₂ reduction with CO generation rate of 365 µmol g⁻¹ h⁻¹ and CO selectivity up to 96% under visible-light irradiation, 7 times higher than that of USTB-17(Ni). After four cycles of reactions, the photocatalytic CO generation rate remains almost unchanged, demonstrating its excellent cycle stability.