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HL: Fachverband Halbleiterphysik
HL 18: Plasmonics and Nanooptics I: Microscopy
HL 18.11: Vortrag
Montag, 7. März 2016, 17:45–18:00, S054
Plasmonic Activation of Platinum Clusters for Photocatalytic Reactions Detected by STM — Sarah Wieghold1, Lea Nienhaus2,3, Marian D. Rötzer1, Fabian Knoller1, Florian F. Schweinberger1, Joseph W. Lyding2, Ulrich Heiz1, Martin Grübele2,3, and •Friedrich Esch1 — 1Chemistry Dept. and CRC, TU München, Lichtenbergstr. 4, 85748 Garching, Germany — 2Beckman Institute, University of Illinois, Urbana — 3Department of Chemistry, University of Illinois, Urbana, Illinois 61801
Their unique structural, optical and electronic properties make small metal clusters prime candidates for catalytic applications, especially under mild reaction conditions such as in photocatalysis. Due to their small cross sections for the interaction with light and due to low surface coverages, an indirect, support-mediated photoactivation mechanism is most efficient. We imaged this activation at the level of individual Pt>35 clusters supported on a thin, structured gold film. The film shows a strong plasmonic interaction with visible light that is optimized to work in a back-illumination geometry. We used a scanning tunneling microscope to map the tunneling current modulation induced by light at 532 nm. When tunneling into unoccupied states of the film, we detect a light-induced current increase that is enhanced on the clusters. In this way, we image the plasmonic coupling of the clusters to the gold support with nanometer resolution. This activation leads indeed to an enhanced catalytic activity, as we demonstrate for the oxidative decomposition of methylene blue.