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

Abstract

Plasmon-induced hot carriers have vast potential for light-triggered highefficiency carrier generation and extraction, which can overcome the optical band gap limit of conventional semiconductor-based optoelectronic devices. Here, it is demonstrated that Au/TiO 2 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/TiO 2 Schottky barrier and migrated to TiO 2 , participating in the chemical reaction occurring at the TiO 2 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 incidentwavelength-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.

Critical Coupling of Visible Light Extends Hot-Electron Lifetimes for H2O2 Synthesis

“…On the basis of these calculations, we estimated an ∼5-fold increase in the LSPR absorbance of our actual Au nanostructures through critical coupling with the Al film. Similar improvements in structural absorption enhancement have been observed in MIM structures, though typically Au is used as the optical mirror. , Our results demonstrate similar enhancements with lower cost Al films.…”

Bright CdSe/CdS Quantum Dot Light-Emitting Diodes with Modulated Carrier Dynamics via the Local Kirchhoff Law

“…Although PHET has been demonstrated useful for the application of plasmon-assisted photocatalysis and photovoltaics, − the direct observation of PHET is rarely reported . In this work, the Coulomb repulsion occurs in the QD assembly when a QD in its ground state is closely surrounded by excited or charged QDs.…”

Au/SiC Microfluidic Devices Fabricated by Rapid Laser Cladding for Photocatalytic Degradation of Water Pollutants

“…To validate the photocatalytic activity of Au/SiC, we investigated the degradation of wastewater in a microchannel flow reactor. Previous studies have shown that microchannel-based photocatalytic reactions are more efficient than those occurring in flat plate flow systems. − To validate the photocatalytic activity of Au/SiC, we developed a microchannel device (Figure A) comprising a PDMS-based serpentine microchannel enclosed by two rigid PMMA substrates with a Au/SiC plate. A 10 W cool white LED and a cooling system were integrated underneath to maximize the compactness and the energy density.…”