Confining Quantum Dots Within Covalent Organic Framework Cages for Coupled CO₂ Photoreduction and Value‐Added Chemical Synthesis

Abstract Coupling photocatalytic CO₂ reduction with the synthesis of value‐added chemicals represents a promising strategy to mitigate carbon emissions while maximizing solar energy utilization. Quantum dots (QDs) are attractive photocatalysts for such tandem reactions, owing to their size‐tunable band structures, abundant surface‐active sites, and strong light‐harvesting capabilities. However, their implementation is often hindered by severe aggregation and sluggish mass transfer, which limit their photocatalytic performance. Herein, a spatially confined 3D/0D covalent organic framework (COF)/ZnSe QDs step‐scheme (S‐scheme) heterojunction photocatalyst is reported, prepared via an in situ encapsulation strategy, for concurrent CO₂ photoreduction and organic transformation. The ZnSe QDs are immobilized within the nanoporous cages of the COF, forming a confined microenvironment that suppresses aggregation, enhances photostability, and promotes efficient mass transfer. As a result, the COF/ZnSe heterostructure achieves a CO generation rate of 128.3 µmol g⁻¹ h⁻¹, while synchronously delivering 95.1% conversion of 1‐phenylethanol to 1‐phenylethanone under light irradiation. The hierarchical COF matrix acts as a nanoreactor, enriching local CO₂ concentration within its porous network, while the rationally designed S‐scheme heterojunction facilitates directional charge flow, ensuring robust redox selectivity. This work provides a generalizable strategy for designing advanced heterostructured photocatalysts for efficient bifunctional solar chemical conversions.