Dichalcogenide and Metal Oxide Semiconductor-Based Composite to Support Plasmonic Catalysis

Abstract

Nanocomposites comprising plasmon active metal nanostructures and semiconductors have been used to control the charge states in the metal to support catalytic activity. In this context dichalcogenides when combined with metal oxides offer the potential to control charge states in plasmonic nanomaterials. Using a model plasmonic mediated oxidation reaction p-amino thiophenol ↔ p-nitrophenol, we show that through the introduction of transition metal dichalcogenide nanomaterial, reaction outcomes can be influenced, achieved through controlling the occurrence of the reaction intermediate dimercaptoazobenzene by opening new electron transfer routes in a semiconductor-plasmonic system. This study demonstrates the ability to control plasmonic reactions by carefully controlling the choice of semiconductors.

Figure 1

(a) Optical absorption spectra (UV–vis) of ZnO NWs (red) MoS₂ (black) ZnO:MoS₂ (blue). Insert: fluorescence spectra of ZnO NWs, MoS₂, and ZnO:MoS₂ also fluorescence spectra of ZnO:MoS₂ at different concentrations. (b) Tauc plots of ZnO NWs and ZnO:MoS₂ to determine the value of the band gap. (c) Raman spectra of ZnO NWs (black), MoS₂ (red) and ZnO:MoS₂ (blue). (d) FTIR spectra of the of ZnO NWs (black) MoS₂ (red) ZnO:MoS₂ (blue) (e) SEM: (i) ZnO NWs, (ii) MoS₂ and (iii) ZnO:MoS₂.

Figure 2

(a) Normalized Raman spectra for PATP or PNTP on a dielectric substrate. (b) Normalized SERS spectra, PATP recorded on AgNPs only (black), ZnO/AgNPs (blue), MoS₂/AgNPs (red) and the composite of ZnO:MoS₂ /AgNPs (Pink). (c) Normalized SERS spectra of PNTP deposited on ZnO/AgNPs, MoS₂/AgNPs and ZnO/MoS₂ /AgNPs (d) Schematic of the oxidation reaction of PATP showing the formation of DMAB and PNTP.

Figure 3

An energy band diagram showing the electronic transition between ZnO:MoS₂ and AgNPs and the PATP analyte molecule. (a) MoS₂/ZnO before contact and (b) formation of MoS₂/ZnO heterojunction.