  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-MoS2 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 MoS2 electronic states close to Fermi level.
