Spatially Separated Plasmonic Catalysts for Selective CO ₂ Electrochemical Conversion Using Interband/Intraband Hot Electrons

Plasmonic nanostructures can utilize solar energy to drive the CO 2 conversion. However, noble metals such as gold and silver struggle to mediate multielectron reduction pathways to value-added products. Here, a spatially separated plasmonic–semiconductor hybrid catalyst is designed by coupling MoS 2 quantum dots to Au triangle nanoprisms. This hybrid enables hot electrons generated from both interband and intraband transitions in Au to cross over the Au–MoS 2 interfacial barrier and inject into MoS 2, thereby improving both the selectivity and activity of the electrocatalytic CO 2 reduction reaction (CO 2 RR). The interband hot electrons with energies near the Au Fermi level tend to correlate with the formation of C 1 products, selectively enhancing methanol production at low overpotential and promoting formic acid at higher overpotentials; meanwhile, the high-energy intraband hot electrons consistently associate with C–C coupling, significantly increasing ethanol selectivity. These results highlight the unique advantage of spatially separated catalysts in plasmon-mediated electrochemical reactions, providing an approach to utilize interband/intraband hot electrons for efficient and selective CO 2 RR.