title: Engineering the Absorption and Field Enhancement Properties of Au-TiO2 Nanohybrids via Whispering Gallery Mode Resonances for Photocatalytic Water Splitting.
abstract: Recently, surface plasmon resonance (SPR) effects have been widely used to construct photocatalysts which are active in the visible spectral region. Such plasmonic photocatalysts usually comprise a semiconductor material transparent in the visible range (such as TiO2) and plasmonic nano-objects (e.g., Au nanoparticles (Au NPs)). Specific SPRs, though, only partially cover the visible spectrum and feature weak light absorption. Here, we explore the unique role played by whispering gallery mode (WGM) resonances in the expression of the photocatalytic activity of plasmonic photocatalysts. Using numerical simulations, we demonstrate that, by solely exploiting a proper geometrical arrangement and WGM resonances in a TiO2 sphere, the plasmonic absorption can be extended over the entire visible range and can be increased by more than 40 times. Furthermore, the local electric field at the Au-TiO2 interface is also considerably enhanced. These results are experimentally corroborated, by means of absorption spectroscopy and Raman measurements. Accordingly, such WGM-assisted plasmonic photocatalysts, when employed in water splitting experiments, exhibit enhanced activity in the visible range. Our findings show a promising and straightforward way to design full solar spectrum photocatalysts.
authors.affiliation: NanoQAM, Quebec Center for Functional Materials, Department of Chemistry, University of Quebec in Montreal , Succ Centre Ville, CP8888, Montreal, Quebec H3C 3P8, Canada.
authors.forename: Jianming
authors.initials: J
authors.lastname: Zhang
authors.affiliation: INRS-EMT , 1650, Boulevard Lionel-Boulet, Varennes, Quebec J3X 1S2, Canada.
authors.forename: Xin
authors.initials: X
authors.lastname: Jin
authors.affiliation: INRS-EMT , 1650, Boulevard Lionel-Boulet, Varennes, Quebec J3X 1S2, Canada.
authors.forename: Pablo I
authors.initials: PI
authors.lastname: Morales-Guzman
authors.affiliation: Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Science , Beijing 100083, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Yu
authors.affiliation: Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Science , Beijing 100083, China.|State Key Laboratory of Crystal Materials, Shandong University , Jinan 250100, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
authors.affiliation: School of Material Science and Engineering, Nanyang Technology University , Singapore 639798, Singapore.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.affiliation: INRS-EMT , 1650, Boulevard Lionel-Boulet, Varennes, Quebec J3X 1S2, Canada.
authors.forename: Luca
authors.initials: L
authors.lastname: Razzari
authors.affiliation: NanoQAM, Quebec Center for Functional Materials, Department of Chemistry, University of Quebec in Montreal , Succ Centre Ville, CP8888, Montreal, Quebec H3C 3P8, Canada.
authors.forename: Jerome P
authors.initials: JP
authors.lastname: Claverie
keywords: Au nanoparticle; TiO2; photocatalysis; plasmonics; whispering gallery mode resonances