Structure Engineered Quantum Dots Couple CO₂ Reduction With Vicinal Diamines Production in a Single Photoredox Cycle

Photocatalytic CO₂ reduction coupled with organic transformations has attracted significant attention as a promising strategy for efficient solar energy utilization. However, challenges remain, particularly when it comes to achieving high selectivity in CO₂ reduction and further expanding the diversity of oxidative organic transformations. Herein, by subtly engineering the structure of CdSe/CdS quantum dots (QDs), we report the integration of photocatalytic CO₂ reduction with vicinal diamines production via oxidative C-C coupling of amines in a single photoredox cycle under visible light. Dynamic experiments indicate the photogenerated electrons for reducing CO₂ proceed in coordination with photogenerated holes oxidizing amines, thus realizing vicinal diamines with yields up to 97% and CO₂-to-CO conversion with selectivity as high as 98%. Mechanistic studies indicate that controlled QD structural engineering optimizes exciton dynamics by balancing electron and hole trapping, ensuring efficient charge separation and utilization. The system is applicable to a range of amine substrates and usable for gram-scale vicinal diamines synthesis, underscoring its potential for synergistic CO₂ valorization and valuable chemicals production.