Electron Filtering by an Intervening ZnS Thin Film in the Gold Nanoparticle-Loaded CdS Plasmonic Photocatalyst

Abstract

In the gold nanoparticle (Au NP)-loaded CdS film on fluorine-doped tin oxide electrode (Au/CdS/FTO), the localized plasmonic resonance excitation-induced electron injection from Au NP to CdS has been proven by photoelectrochemical measurements. Formation of ZnS thin films between the Au NP and CdS film leads to a drastic increase of the photocurrent under visible-light irradiation (λ > 610 nm) in a 0.1 M NaClO aqueous electrolyte solution due to the electron filtering effect. The photocurrent strongly depends on the thickness of the ZnS film, and the maximum value is obtained at a thickness as thin as 2.1 nm. Furthermore, the ZnS overlayer significantly stabilizes the photocurrent of the CdS/FTO electrode in a polysulfide/sulfide electrolyte solution even under the excitation of CdS (λ > 430 nm). This work presents important information about the design for new plasmonic photocatalysts consisting of plasmonic metal NPs and chalcogenide semiconductors with high conduction band edge.

Rational design for gold nanoparticle-based plasmonic catalysts and electrodes for water oxidation towards artificial photosynthesis

“…The holes left in the Au NPs cause the oxidation reaction. 23 In addition, there is also a possibility of a direct electronic transition from the Au NP to the CB of CdS. 24 Thus, in principle, visible-to-near infrared light can be utilized as the driving force for reactions in HET-type plasmonic photocatalysts (section 3.3).…”

Nanohybrid Crystals with Heteroepitaxial Junctions for Solar-to-Chemical Transformations

“…Efficient hot-electron injection from Au NP to CdS through the high-quality interface can also be expected in the HC-Au@#CdS system (see section ). Further, HC-Au@#CdS possesses unique optical properties as compared to the usual Au NP-loaded CdS (Au/CdS) system (Figure b). The absorption edge of CdS is located at λ = 520 nm, while the Au colloid has the LSPR peak at the same wavelength.…”

“…The high photocatalytic activity and stability of HC-Au@#CdS under red-light irradiation can be accounted for in terms of the hot-electron transfer mechanism (Figure c). The selective LSPR-excitation by the red-light irradiation generates hot electrons in the Au core, which can be partly injected into the CB of CdS (Figure c) . The electrons with highly negative potential reduce water to yield H 2 .…”

“…The selective LSPR-excitation by the red-light irradiation generates hot electrons in the Au core, which can be partly injected into the CB of CdS (Figure 6c). 38 The electrons with highly negative potential reduce water to yield H 2 . The lowering in the Fermi energy (E F ) of Au NP with the IFET can be the driving force for OER.…”

Overall water splitting and hydrogen peroxide synthesis by gold nanoparticle-based plasmonic photocatalysts

“…HC-Au@#CdS efficiently absorbs sunlight. The hot-electrons generated by the LSPR excitation can be effectively injected into the CB of CdS [60][61][62] through the large area and high-quality junction. 59 The high-energy electrons in the CB of CdS enable a smooth HER, while the hot holes le in Au NPs oxidize water with the aid of the electrocatalytic activity for the WOR.…”