Interface Reinforced Tailoring of Quantum Dots Regulates Reaction Trajectory of CO₂ Photoreduction

Artificial photosynthesis using semiconductor quantum dots (QDs) is one of the most promising pathways toward converting CO₂ into valuable chemicals. However, the multistep process of CO₂-to-chemical conversion endows the regulation of reaction trajectory from CO₂ to specific products very challenging in aqueous solution. Here, it is first disclosed that the anisotropic growth of CdSe−S−InS interface in ultrafine heterojunction QDs alters the trajectory of CO₂ photoreduction in water, i.e., CdSe/S/InS QDs mainly produce CO while CdSe QDs generate HCOO⁻. Under optimal conditions, the CO turnover number of CdSe/S/InS QDs is ≈1000 (12 h; vs QDs) with a selectivity of >96% in C-based products or ≈57.6% when considering H₂. The formation of anisotropic CdSe/S/InS ultrafine heterojunction facilitates charge migration at the interface, which is confirmed by X-ray photoelectron spectroscopy and transient absorption spectroscopy. Further DFT simulations and in situ experiments demonstrate that the interfacial lattice expansion reinforces the charge difference at the interface, thus contributing to the product shift from HCOOH to CO, which clarifies the mechanism of interface-reinforced tailoring of CO₂ reaction trajectories. This work can not only provide guidance for interfacial CO₂ activation mode in water but also inspire the design of novel artificial photocatalysts with new functions.