Phase transition and electronic structure investigation of MoS₂-reduced graphene oxide nanocomposite decorated with Au nanoparticles

Abstract

In this work a simple approach to transform MoS 2 from its metallic (1T' to semiconductor 2H) character via gold nanoparticle surface decoration of a MoS 2 graphene oxide (rGO) nanocomposite is proposed. The possible mechanism to this phase transformation was investigated using different spectroscopy techniques, and supported by density functional theory theoretical calculations. A mixture of the 1T'and 2H-MoS 2 phases was observed from the Raman and Mo 3d High Resolution X-ray photoelectron (HRXPS) spectra analysis in the MoS 2 -rGO nanocomposite. After surface decoration with gold nanoparticles the concentration of the 1T' phase decreases making evident a phase transformation. According to Raman and valence band spectra analyses, the AuNPs induces a p-type doping in MoS 2 -rGO nanocomposite. We proposed as a main mechanism to the MoS 2 phase transformation the electron transfer from Mo 4d xy,xz,yz in 1T' phase to AuNPs conduction band. At the same time, the unoccupied electronic structure was investigated from S K-edge Near Edge X-Ray Absorption Fine Structure (NEXAFS) spectroscopy. Finally, the electronic coupling between unoccupied electronic states was investigated by the core hole clock approach using Resonant Auger spectroscopy (RAS), showing that AuNPs affect mainly the MoS 2 electronic states close to Fermi level.

Near-Infrared Optical Response and Carrier Dynamics for High Photoconversion in Tellurene

“…The latter, in particular, is a crucial factor for the enhanced absorption of electromagnetic radiation. Thus, the transition-metal dichalcogenides ,− (TMDCs) and monoelemental crystals (X-enes), − whose optical band gaps span the mid-infrared and visible spectrum, are emerging as promising semiconductors for flexible optoelectronic devices.…”

Efficient hot carrier dynamics in near-infrared photocatalytic metals

“…Noble metals belong to a class of materials whose physical properties have been extensively studied, both theoretically [1][2][3][4][5][6] and experimentally [7][8][9][10]. This has lead to a wide range of applications in photovoltaics [11,12], plasmonics [13,14], and most recently in an emergent area called plasmonic catalysis [15][16][17].…”

Understanding ultrafast charge transfer processes in SnS and SnS2: using the core hole clock method to measure attosecond orbital-dependent electron delocalisation in semiconducting layered materials

“…Despite the unique charge transfer dynamics information that this method can provide, only seven CHC publications have appeared so far on such systems. These publications have focused on the study of three different metal chalcogenides: MoS2, [31][32][33][34] TaS2 35 and SnS2. 36,37 and shown the sensitivity of the technique to measure changes in the charge transfer dynamics depending on material phase, 32,34 additives 34 and substrate interactions.…”