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Local Electric Field-Enhanced Plasmonic Photocatalyst: Formation of Ag Cluster-Incorporated AgBr Nanoparticles on TiO2

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journal contribution
posted on 2016-08-22, 00:00 authored by Yoshihiro Hayashido, Shin-ichi Naya, Hiroaki Tada
A successive ionic layer adsorption and reaction-photoreduction (SILAR-PR) technique forms Ag clusters mainly in the interior of AgBr nanoparticles (NPs) on the TiO2 surface (Ag@AgBr/mp-TiO2). The localized surface plasmon resonance (LSPR) of Ag NP-loaded TiO2 (Ag/mp-TiO2) rapidly weakens in the air at room temperature. In contrast, the LSPR intensity of Ag@AgBr/mp-TiO2 is preserved in the air at least for several days. Ag@AgBr/mp-TiO2 stably exhibits a high level of photocatalytic activity for the decomposition of 2-naphthol under irradiation of visible-light (λ > 400 nm), whereas Ag­(core)–SiO2(shell) NP-incorporated TiO2 (TiO2/Ag@SiO2) is only active near UV region (J. Am. Chem. Soc. 2008, 130, 1676). Spectroscopic and photoelectrochemical measurements suggested that the high photocatalytic activity of Ag@AgBr/mp-TiO2 stems from the enhancement of the local electric field near Ag clusters increasing the rate of the photocharge carrier generation in AgBr in a manner similar to the TiO2/Ag@SiO2 system. Eventually, AgBr plays the role of not only a visible-light photocatalyst but also an oxidation inhibitor of Ag clusters, while Ag cluster acts as an amplifier for the local electric field.