Spatially Separated Plasmonic Catalysts for Selective CO ₂ 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.