Integration of metal-organic layers with quantum dots for artificial photosynthesis

Metal-organic layers (MOLs), a type of new-emerging two-dimensional ultrathin metal-organic framework materials with large surface areas and highly exposed active sites, have shown promising applications in photocatalytic CO₂ reduction. However, due to a lack of photosensitivity and photooxidation capability, photosensitizers and sacrificial reductants are usually necessary for MOLs-based photocatalytic CO₂ reduction systems. In this article, by integration of MOLs and quantum dots (QDs), we constructed MOLs-based catalysts with multi-functions of photosensitivity, photoreduction and photooxidation, which thus can serve as photocatalysts for CO₂ reduction with H₂O as an electron donor. Specifically, by an electrostatic self-assembly approach, nickel(II)-based MOLs (Ni-MOLs) and CsPbBr₃ QDs have been assembled, constructing valid II-Scheme Ni-MOLs/CsPbBr₃ heterojunctions with close Ni-MOLs/CsPbBr₃ heterointerface. Such a close heterointerface shortens the charge transfer distance, thus effectively boosting the charge separation and transfer. As a result, upon illumination by visible light (λ ⩾ 400 nm, 100 mW cm⁻²), the optimized photocatalyst shows high efficiency and stability in photochemical CO₂ reduction in the absence of any photosensitizers and sacrificial reductants. The CO yield reaches as high as 124 µmol g⁻¹ in 4 h, over 6 times higher than that achieved by CsPbBr₃. Additionally, the selectivity reaches 100%. This work provides a new way to construct MOL-based catalysts for artificial photosynthesis.