title: Plasmonically Enhanced Photocatalytic Hydrogen Production from Water: The Critical Role of Tunable Surface Plasmon Resonance from Gold-Silver Nanoshells.
abstract: Gold-silver nanoshells (GS-NSs) having a tunable surface plasmon resonance (SPR) were employed to facilitate charge separation of photoexcited carriers in the photocalytic production of hydrogen from water. Zinc indium sulfide (ZnIn2S4; ZIS), a visible-light-active photocatalyst, where the band gap varies with the [Zn]/[In] ratio, was used as a model ZIS system (E(g) = 2.25 eV) to investigate the mechanisms of plasmonic enhancement associated with the nanoshells. Three types of GS-NS cores with intense absorptions centered roughly at 500, 700, and 900 nm were used as seeds for preparing GS-NS@ZIS core-shell structures via a microwave-assisted hydrothermal reaction, yielding core-shell particles with composite diameters of ∼200 nm. Notably, an interlayer of dielectric silica (SiO2) between the GS-NSs and the ZIS photocatalyst provided another parameter to enhance the production of hydrogen and to distinguish the charge-transfer mechanisms. In particular, the direct transfer of hot electrons from the GS-NSs to the ZIS photocatalyst was blocked by this layer. Of the 10 particle samples examined in this study, the greatest hydrogen gas evolution rate was observed for GS-NSs having a SiO2 interlayer thickness of ∼17 nm and an SPR absorption centered at ∼700 nm, yielding a rate 2.6 times higher than that of the ZIS without GS-NSs. The apparent quantum efficiencies for these core-shell particles were recorded and compared to the absorption spectra. Analyses of the charge-transfer mechanisms were evaluated and are discussed based on the experimental findings.
authors.affiliation: Department of Chemistry and the Texas Center for Superconductivity, University of Houston , 4800 Calhoun Road, Houston, Texas 77204-5003, United States.
authors.forename: Chien-Hung
authors.initials: CH
authors.lastname: Li
authors.affiliation: Department of Chemical and Materials Engineering, National Central University , 300 Jhongda Road, Jhongli City 32001, Taiwan.
authors.forename: Min-Chih
authors.initials: MC
authors.lastname: Li
authors.affiliation: Department of Chemical and Materials Engineering, National Central University , 300 Jhongda Road, Jhongli City 32001, Taiwan.
authors.forename: Si-Ping
authors.initials: SP
authors.lastname: Liu
authors.affiliation: Department of Chemistry and the Texas Center for Superconductivity, University of Houston , 4800 Calhoun Road, Houston, Texas 77204-5003, United States.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Jamison
authors.affiliation: Materials Science & Engineering, University of Houston , Houston, Texas 77204, United States.
authors.forename: Dahye
authors.initials: D
authors.lastname: Lee
authors.affiliation: Department of Chemistry and the Texas Center for Superconductivity, University of Houston , 4800 Calhoun Road, Houston, Texas 77204-5003, United States.
authors.forename: T Randall
authors.initials: TR
authors.lastname: Lee
authors.affiliation: Department of Chemical and Materials Engineering, National Central University , 300 Jhongda Road, Jhongli City 32001, Taiwan.
authors.forename: Tai-Chou
authors.initials: TC
authors.lastname: Lee
keywords: gold−silver nanoshells; hydrogen energy; photocatalyst; surface plasmon resonance; zinc indium sulfide