X-ray diffraction (XRD) is utilized to assign the crystal structure of the synthesized materials as hexagonal 2H-MoS2 according to PDF card #01-071-9809 (Fig. ). The interlayer distance is identified according to the (002) signal at ca. 13.9° 2θ as 6.15 Å for both nano-MoS2 and micro-MoS2 samples. A significant peak broadening of the (002) peak at 13.9° for nano-MoS2 is a further qualitative confirmation of the reduced crystalline domain size compared to micro-MoS2. Raman spectra of the two samples (Fig. ) show the two main characteristic peaks at 382 and 406 cm -1 , which correspond to E 1 2g and A1g vibrational modes of the semiconducting (2H) phase. The results confirm that the employed hydrothermal synthesis route leads to the formation of 2H-MoS2, independent of crystallite size.