Prolonged Hot Electron Dynamics in Plasmonic-Metal/Semiconductor (Au/TiO2) Heterostructures with Implications for Solar Photocatalysis

Ideal solar-to-fuel photocatalysts must effectively harvest sunlight to generate the significant quantities of long-lived charge carriers necessary for chemical reactions. Here we demonstrate the merits of augmenting traditional photoelectrochemical cells with plasmonic nanoparticles to satisfy these daunting photocatalytic requirements. Electrochemical techniques were employed to elucidate the mechanics of plasmon-mediated electron transfer in Au/TiO₂ heterostructures in solution under visible-light (λ > 515 nm) irradiation. Significantly, we discovered that these transferred electrons displayed excited-state lifetimes two orders of magnitude longer than those of electrons photogenerated directly within TiO₂ via UV excitation. These long-lived electrons further enable visible-light-driven H₂ evolution from water, heralding a new photocatalytic paradigm for solar energy conversion.