Plasmonic Au/TiO2-Dumbbell-On-Film Nanocavities for High-Efficiency Hot-Carrier Generation and Extraction

Kwun Hei Willis Ho, Aixue Shang, Fenghua Shi, Tsz Wing Lo, Pui Hong Yeung, Yat Sing Yu, Xuming Zhang, Kwok yin Wong, Dang Yuan Lei (Corresponding Author)

Research output: Journal article publicationJournal articleAcademic researchpeer-review

52 Citations (Scopus)


Plasmon-induced hot carriers have vast potential for light-triggered high-efficiency carrier generation and extraction, which can overcome the optical band gap limit of conventional semiconductor-based optoelectronic devices. Here, it is demonstrated that Au/TiO2 dumbbell nanostructures assembled on a thin Au film serve as an efficient optical absorber and a hot-carrier generator in the visible region. Upon excitation of localized surface plasmons in such coupled particle-on-film nanocavities, the energetic conduction electrons in Au can be injected over the Au/TiO2 Schottky barrier and migrated to TiO2, participating in the chemical reaction occurring at the TiO2 surface. Compared with the same dumbbell nanostructures on an indium tin oxide (ITO) film, such nanocavities exhibit remarkable enhancement in both photocurrent amplitude and reaction rate that arise from increased light absorption and near-field amplification in the presence of the Au film. The incident-wavelength-dependent photocurrent and reaction rate measurements jointly reveal that Au-film-mediated near-field localization facilitates more efficient electron–hole separation and transport in the dumbbells and also promotes strong d-band optical transitions in the Au film for generation of extra hot electrons. Such nanocavities provide a new plasmonic platform for effective photoexcitation and extraction of hot carriers and also better understanding of their fundamental science and technological implications in solar energy harvesting.

Original languageEnglish
Article number1800383
JournalAdvanced Functional Materials
Issue number34
Publication statusPublished - 22 Aug 2018


  • Au/TiO dumbbell nanostructures
  • hot carriers
  • particle-on-film nanocavities
  • surface plasmons
  • visible-light photocatalysis

ASJC Scopus subject areas

  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics


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