Light-induced ultrafast proton-coupled electron transfer responsible for H₂ evolution on silver plasmonics

Light-driven proton-coupled electron transfer (PCET) reactions on nanoplasmonics would bring temporal control of their reactive pathways, in particular, prolong their charge separation state. Using a silver nano-hybrid plasmonic structure, we observed that optical excitation of Ag-localized surface plasmon instigated electron injection into TiO₂ conduction band and oxidation of isopropanol alcoholic functionality. Femtosecond transient infrared absorption studies show that electron transfer from Ag to TiO₂ occurs in ca. 650 fs, while IPA molecules near the Ag surface undergo an ultrafast bidirectional PCET step within 400 fs. Our work demonstrates that ultrafast PCET reaction plays a determinant role in prolonging charge separation state, providing an innovative strategy for visible-light photocatalysis with plasmonic nanostructures.