Quantum Dot Visible-Light Photocatalysis Programs CO₂ for Hydrocarboxylation and Carbonylation Reactions

Homogeneous photocatalysis has greatly expanded the use of CO₂ as a renewable one-carbon (C1) feedstock in organic synthesis, yet, controlling sequential proton/electron transfer kinetics and recovering the photocatalyst remain challenging. Here, we report that semiconductor quantum dots (QDs) provide a visible-light-driven heterogeneous platform that directs CO₂ activation toward either one-electron radical anion (CO₂ ^•-) or carbon monoxide (CO). Regulating interfacial proton transfer kinetics governs the fates of surface-bound CO₂ ^•- intermediate. Slowing the first proton transfer prolongs CO₂ ^•- lifetime, enabling its in situ interception by aromatic and aliphatic alkenes to afford carboxylic acids with exclusive β-selectivity. Meanwhile, the remaining CO is used as an ex situ C1 feedstock in carbonylation reaction. Moreover, facilitating sequential proton transfer promotes the transformation of CO₂ ^•- intermediate to CO, the diverse carbonylation reactions proceed with good to excellent yields. This strategy can also enable ¹³C-labeled product and gram-scale synthesis. This work establishes QDs as a versatile and tunable heterogeneous platform for CO₂ valorization in organic synthesis, offering complementary advantages over homogeneous systems for divergent C─C bond formation.