Plasmonic-metal/semiconductor heterostructures represent promising photocatalytic constructs for solar-to-fuel energy conversion, but detailed knowledge of the structure-function relationships governing their activity remains elusive. Here, we monitor plasmon-mediated electron transfer (PMET) across Au-TiO2 Schottky junctions at the single-nanoparticle level to clarify the role of metal nanocrystal size in plasmonic photochemistry. Size-dependent photovoltage studies of PMET in Au/TiO2 photoelectrodes reveal that the reduction potential of hot electrons within the TiO2 conduction band is not solely determined by the absolute size of Au nanoparticles, but by the relative size of Au to TiO2. With this new insight, we tailored the physical dimensions of Au/TiO2 photocatalysts to efficiently harvest hot electrons for improved plasmon-driven hydrogen evolution from water. Taken together, these studies elucidate the role of metal nanocrystal size in plasmonic photocatalysis and establish general guidelines for the rational design of plasmonic-metal/semiconductor assemblies that can effectively exploit hot carriers in photochemical reactions.

Surface plasmon-driven water reduction: Nanoparticle size matters

256th National Meeting (2018)

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