Molecular Recognition and Spatial Confinement in CD-MOF Drive Tandem Photocatalytic CO2 Reduction and Alcohol Oxidation.

The full utilization of both photocatalytic reduction and oxidation reactions is highly attractive for atom-economic and sustainable chemical synthesis. However, coupling CO2 reduction with oxidation of liquid organics is challenging, as their disparate physicochemical properties lead to mismatched adsorption, diffusion, and activation at a common interface. Effective integration requires precise molecular recognition to selectively bind each substrate molecule and tailored spatial confinement to bring them into reactive proximity. Herein, we engineered dual functionality by assembling a cyclodextrin metal-organic framework (CD-MOF) onto ZnCdS nanoparticles. The γ-CD cavities exhibit molecular recognition of benzyl alcohol via host-guest interactions, while the porous framework has spatial confinement effects and accumulates CO2 molecules. This well-defined microenvironment with an interfacial dipole field enhances charge separation, accelerates interfacial electron transfer, and drives efficient tandem photoreactions. Under visible light illumination, CO has been produced at a rate of 1195.1 µmol·g- 1·h- 1 (14.5-folds higher than pristine ZnCdS). Meanwhile, benzyl alcohol is oxidized to benzaldehyde with nearly 100% selectivity, rivaling state-of-the-art performance among non-precious metal systems. This work establishes a supramolecular paradigm of programmable host-guest microenvironments to orchestrate photoredox transformations.