Spatially Separated Plasmonic Catalysts for Selective CO2 Electrochemical Conversion Using Interband/Intraband Hot Electrons

Plasmonic nanostructures can utilize solar energy to drive the CO2 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 MoS2 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–MoS2 interfacial barrier and inject into MoS2, thereby improving both the selectivity and activity of the electrocatalytic CO2 reduction reaction (CO2RR). The interband hot electrons with energies near the Au Fermi level tend to correlate with the formation of C1 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 CO2RR.