Enhanced water splitting under modal strong coupling conditions

Xu Shi, Kosei Ueno, Tomoya Oshikiri, Quan Sun, Keiji Sasaki, Hiroaki Misawa

Research output: Contribution to journalArticlepeer-review

74 Scopus citations

Abstract

Strong coupling between plasmons and optical modes, such as waveguide or resonator modes, gives rise to a splitting in the plasmon absorption band. As a result, two new hybrid modes are formed that exhibit near-field enhancement effects. These hybrid modes have been exploited to improve light absorption in a number of systems. Here we show that this modal strong coupling between a Fabry-Perot nanocavity mode and a localized surface plasmon resonance (LSPR) facilitates water splitting reactions. We use a gold nanoparticle (Au-NP)/TiO2/Au-film structure as a photoanode. This structure exhibits modal strong coupling between the Fabry-Perot nanocavity modes of the TiO2 thin film/Au film and LSPR of the Au NPs. Electronic excitation of the Au NPs is promoted by the optical hybrid modes across a broad range of wavelengths, followed by a hot electron transfer to TiO2. A key feature of our structure is that the Au NPs are partially inlaid in the TiO2 layer, which results in an enhancement of the coupling strength and water-oxidation efficiency. We observe an 11-fold increase in the incident photon-to-current conversion efficiency with respect to a photoanode structure with no Au film. Also, the internal quantum efficiency is enhanced 1.5 times under a strong coupling over that under uncoupled conditions.
Original languageEnglish
Pages (from-to) 953-+
JournalNature Nanotechnology
Volume13
Issue number10
DOIs
StatePublished - Oct 2018

Keywords

  • METAL NANOSTRUCTURES; PLASMON; GENERATION; ABSORBERS; BAND

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