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Proceedings Paper

Ultrafast carrier dynamics unravel role of surface ligands and metal domain size on the photocatalytic hydrogen evolution efficiency of Au-tipped CdS nanorods: an ultrafast transient absorption spectroscopy study
Author(s): Yuval Ben-Shahar; Ilka Kriegel; Francesco Scotognella; Nir Waiskopf; Stefano Dal Conte; Luca Moretti; Giulio Cerullo; Eran Rabani; Uri Banin D.V.M.
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Paper Abstract

Semiconductor-metal hybrid nanostructures are interesting materials for photocatalysis. Their tunable properties offer a highly controllable platform to design light-induced charge separation, a key to their function in photocatalytic water splitting. Hydrogen evolution quantum yields are influenced by factors as size, shape, material and morphology of the system, additionally the surface coating or the metal domain size play a dominant role.

In this paper we present a study on a well-defined model system of Au-tipped CdS nanorods. We use transient absorption spectroscopy to get insights into the charge carrier dynamics after photoexcitation of the bandgap of CdS nanorods. The study of charge transfer processes combined with the hydrogen evolution efficiency unravels the effects of surface coating and the gold tip size on the photocatalytic efficiency. Differences in efficiency with various surface ligands are primarily ascribed to the effects of surface passivation. Surface trapping of charge carriers is competing with effective charge separation, a prerequisite for photocatalysis, leading to the observed lower hydrogen production quantum yields. Interestingly, non-monotonic hydrogen evolution efficiency with size of the gold tip is observed, resulting in an optimal metal domain size for the most efficient photocatalysis. These results are explained by the sizedependent interplay of the metal domain charging and the relative band-alignments. Taken together our findings are of major importance for the potential application of hybrid nanoparticles as photocatalysts.

Paper Details

Date Published: 23 February 2017
PDF: 8 pages
Proc. SPIE 10102, Ultrafast Phenomena and Nanophotonics XXI, 101021L (23 February 2017); doi: 10.1117/12.2251908
Show Author Affiliations
Yuval Ben-Shahar, The Hebrew Univ. of Jerusalem (Israel)
Ilka Kriegel, Politecnico di Milano, IFN, CNR (Italy)
Istituto Italiano di Tecnologia (Italy)
Francesco Scotognella, Politecnico di Milano, IFN, CNR (Italy)
Nir Waiskopf, The Hebrew Univ. of Jerusalem (Israel)
Stefano Dal Conte, Politecnico di Milano, IFN, CNR (Italy)
Luca Moretti, Politecnico di Milano, IFN, CNR (Italy)
Giulio Cerullo, Politecnico di Milano, IFN, CNR (Italy)
Eran Rabani, Univ. of California, Berkeley (United States)
Lawrence Berkeley National Lab. (United States)
Tel Aviv Univ. (Israel)
Uri Banin D.V.M., The Hebrew Univ. of Jerusalem (Israel)

Published in SPIE Proceedings Vol. 10102:
Ultrafast Phenomena and Nanophotonics XXI
Markus Betz; Abdulhakem Y. Elezzabi, Editor(s)

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