Concurrent Photocatalytic CO2 Reduction and 1-Phenylethanol Oxidation Regulated by Chloride Ion-Capped CdS@ZnxCd1-xS@ZnS QDs

Solar-driven photocatalytic CO 2 reduction coupled with the oxidation of organic compounds to value-added chemicals is a promising strategy, which can utilize both photogenerated electrons and holes. Here, a gradient alloyed CdS@Zn x Cd 1-x S@ZnS quantum dots (quasi-Type II band structure) capped with Cl − ligands demonstrate great potential in the simultaneous conversion of CO 2 and 1-phenylethanol into syngas and pinacol. The passivation with Cl − maximizes the exposure of surface-active sites and improves their electronic structure, providing a prerequisite for the efficient execution of redox reactions. More importantly, the p–π conjugation between chloride-ion ligands and the benzene ring provides a bridge for the ultrafast transfer of holes, which greatly promotes the activation of the Cα─H bond in 1-phenylethanol to release a mass of reactive free hydrogen. This process effectively lowers the thermodynamic energy barrier for CO 2 reduction, even as the excessively high kinetic energy barriers arising from the accumulation of excess protons also enable them to self-couple, leading to the generation of syngas (CO ≈ 75 mmol g −1 h −1 ; selectivity ≈ 69.86%). This work provides insights for future artificial photosynthesis to achieve high activity and cost-effective conversion of CO 2 into storable renewable resources and the co-production of value-added substances through synergistic organic oxidation.