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.

Bimetallic Nanoparticles: Enhanced Magnetic and Optical Properties for Emerging Biological Applications

“…This technique was utilized to synthesize core-shell nanoparticles by Mancier et al for the generation of Cu@Ag nanoparticles [101]. Similarly, Li and co-workers combined galvanic replacement and diffusion through a protective porous silica shell to synthesize SiO 2 -coated hollow AgAu nanoparticles for use as stable plasmonic agents for NIR activation [1].…”

“…The synthesis and properties of metallic nanoparticles (NPs) has been extensively studied over decades, not only because of their unique properties, but also because of their potential applications in catalysis, electronics, optoelectronics, information storage, biosensors, and surface-enhanced Raman spectroscopy (SERS) [1][2][3][4][5][6][7][8][9][10]. Nanoparticles can exist as common structural elements or composites, and they have a wide functional diversity compared to bulk materials.…”

SiO2@ZnIn2S4 Core-shell Nanoparticles for Photocatalytic Hydrogen Evolution

“…Note also that an interlayer of SiO2 between the GS-NSs and the ZIS photocatalyst provided another key parameter to control the hydrogen production. Our studies showed that this unique GS-NS@SiO2@ZIS coreshell particles exhibited a unique plasmonic-enhanced photocatalytic hydrogen production [3] [4]. The matching of the absorptions between GS-NSs and ZIS, and the thickness of SiO2 interlayer play important roles on the charge transfer mechanism [4].…”

“…Our studies showed that this unique GS-NS@SiO2@ZIS coreshell particles exhibited a unique plasmonic-enhanced photocatalytic hydrogen production [3] [4]. The matching of the absorptions between GS-NSs and ZIS, and the thickness of SiO2 interlayer play important roles on the charge transfer mechanism [4]. However, the coverage, thickness, and crystallinity of ZIS on top of the SiO2 interlayer were not systematically investigated.…”

Bimetallic Nanoparticles: Enhanced Magnetic and Optical Properties for Emerging Biological Applications

“…The synthesis and properties of metallic nanoparticles (NPs) has been extensively studied over decades, not only because of their unique properties, but also because of their potential applications in catalysis, electronics, optoelectronics, information storage, biosensors, and surfaceenhanced Raman spectroscopy (SERS) [1][2][3][4][5][6][7][8][9][10]. Nanoparticles can exist as common structural elements or composites, and they have a wide functional diversity compared to bulk materials.…”