Molybdenum disulfide (MoS2) has attracted great attention due to its distinctive electronic, optical, chemical, and mechanical properties. In almost all of these applications, having a clear understanding about the wetting properties of MoS2 is essential. The basal plane of MoS2 has been generally believed to be hydrophobic with water contact angle (WCA) around 90°. Kozbial et al. have recently suggested that the freshly exfoliated MoS2 was intrinsically relative hydrophilic (WCA = 69.0 ± 3.8°); however, it could become fairly hydrophobic after 1 day exposure to the ambient air (WCA = 89.0 ± 3.1°) (Kozbial et al. Understanding the Intrinsic Water Wettability of Molybdenum Disulfide (MoS2). Langmuir 2015, 31, 8429–8435). They contributed this change in wetting properties to the adsorption of airborne hydrocarbons. The number of layers is another important factor that is believed to affect the wetting properties in ultrathin MoS2 films. For highly crystalline samples grown at high temperature (900°C), Gaur ...