Molybdenum disulfide (MoS2) samples were synthesized using a one-pot hydrothermal method, following the procedure outlined by Geng et al. 300 mg MoO3 (Alfa Aesar), 450 mg thioacetamide (Thermo Fisher Scientific), and 3 g urea (Merck KGaA) were dissolved in 50 ml deionized water and stirred for 30 minutes in a glass beaker. To control the pH of the solution, 1 M hydrochloric acid (HCl, Merck) or 1 M lithium hydroxide (LiOH, Merck) were added as needed to reach either pH 1 (Nano-MoS2) or pH 5.5 (Micro-MoS2), respectively. The pH was measured using a pH meter (Blueline 14 pH/Xylem Analytics). The solution was transferred to a 100 ml Teflon vessel, which was used for hydrothermal synthesis in an autoclave (BRHS-100, Berghof). The synthesis temperature was set at 235 °C and maintained for two hours after reaching the target temperature. The pressure in the autoclave was maintained at ca. 13 -18 bar. The reaction products were collected by centrifugation at 6000 rpm for 10 min, followed by vacuum filtration with washing in deionized water and ethanol. The filtered powder was dried at 80 °C in an oven overnight.