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

Yuval Ben-Shahar, Ilka Kriegel, Francesco Scotognella, Nir Waiskopf, Stefano Dal Conte, Luca Moretti, Giulio Cerullo, Eran Rabani, Uri Banin

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Scopus citations

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.

Original languageAmerican English
Title of host publicationUltrafast Phenomena and Nanophotonics XXI
EditorsMarkus Betz, Abdulhakem Y. Elezzabi
PublisherSPIE
ISBN (Electronic)9781510606456
DOIs
StatePublished - 2017
EventUltrafast Phenomena and Nanophotonics XXI 2017 - San Francisco, United States
Duration: 30 Jan 20172 Feb 2017

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume10102
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferenceUltrafast Phenomena and Nanophotonics XXI 2017
Country/TerritoryUnited States
CitySan Francisco
Period30/01/172/02/17

Bibliographical note

Publisher Copyright:
© COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

Keywords

  • Metal domain size
  • Photocatalysis
  • Semiconductor-metal hybrid nanocrystals
  • Surface ligands
  • Ultrafast carrier dynamics

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