In Situ Growth of Cs₃Bi₂Br₉ Quantum Dots on Bi-MOF Nanosheets via Cosharing Bismuth Atoms for CO₂ Capture and Photocatalytic Reduction

Given the global warming caused by excess CO2 accumulation in the atmosphere, it is essential to reduce CO2 by capturing and converting it to chemical feedstock using solar energy. Herein, a novel Cs3Bi2Br9/bismuth-based metal-organic framework (Bi-MOF) composite was prepared via an in situ growth strategy of Cs3Bi2Br9 quantum dots (QDs) on the surface of Bi-MOF nanosheets through coshared bismuth atoms. The prepared Cs3Bi2Br9/Bi-MOF exhibits bifunctional merits for both the high capture and effective conversion of CO2, among which the optimized 3Cs3Bi2Br9/Bi-MOF sample shows a CO2-CO conversion yield as high as 572.24 μmol g-1 h-1 under the irradiation of a 300 W Xe lamp. In addition, the composite shows good stability after five recycles in humid air, and the CO2 photoreduction efficiency does not decrease significantly. The mechanistic investigation uncovers that the intimate atomic-level contact between Cs3Bi2Br9 and Bi-MOF via the coshared atoms not only improves the dispersion of Cs3Bi2Br9 QDs over Bi-MOF nanosheets but also accelerates interfacial charge transfer by forming a strong bonding linkage, which endows it with the best performance of CO2 photoreduction. Our new finding of bismuth-based metal-organic framework/lead-free halide perovskite by cosharing atoms opens a new avenue for a novel preparation strategy of the heterojunction with atomic-level contact and potential applications in capture and photocatalytic conversion of CO2.