A Plasmonic Photocatalyst Consisting of Silver Nanoparticles Embedded in Titanium Dioxide

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• 作者：Koichi Awazu ; Makoto Fujimaki ; Carsten Rockstuhl ; Junji Tominaga ; Hirotaka Murakami ; Yoshimichi Ohki ; Naoya Yoshida ; Toshiya Watanabe
• 刊名：Journal of the American Chemical Society
• 出版年：2008
• 出版时间：February 6, 2008
• 年：2008
• 卷：130
• 期：5
• 页码：1676 - 1680
• 全文大小：243K
• 年卷期：v.130,no.5(February 6, 2008)
• ISSN：1520-5126

文摘

Titanium dioxide (TiO₂) displays photocatalytic behavior under near-ultraviolet (UV) illumination.In another scientific field, it is well understood that the excitation of localized plasmon polaritons on thesurface of silver (Ag) nanoparticles (NPs) causes a tremendous increase of the near-field amplitude atwell-defined wavelengths in the near UV. The exact resonance wavelength depends on the shape and thedielectric environment of the NPs. We expected that the photocatalytic behavior of TiO₂ would be greatlyboosted if it gets assisted by the enhanced near-field amplitudes of localized surface plasmon (LSP). Herewe show that this is true indeed. We named this new phenomenon "plasmonic photocatalysis". The key toenable plasmonic photocatalysis is to deposit TiO₂ on a NP comprising an Ag core covered with a silica(SiO₂) shell to prevent oxidation of Ag by direct contact with TiO₂. The most appropriate diameter for AgNPs and thickness for the SiO₂ shell giving rise to LSP in the near UV were estimated from Mie scatteringtheory. Upon implementing a device that took these design considerations into account, the measuredphotocatalytic activity under near UV illumination of such a plasmonic photocatalyst, monitored bydecomposition of methylene blue, was enhanced by a factor of 7. The enhancement of the photocatalyticactivity increases with a decreased thickness of the SiO₂ shell. The plasmonic photocatalysis will be of useas a high performance photocatalyst in nearly all current applications but will be of particular importancefor applications in locations of minimal light exposure.