It is generally accepted that graphitic surfaces, such as supported graphene and graphite, are hydrophobic and their water contact angles (WCAs) are in the range of 80° - 90°. In this talk, I will show that freshly prepared Cu-supported graphene and graphite surfaces are in fact hydrophilic with a WCA of ca. 44° and 64°, respectively [1]. The WCA of these surfaces increase when they are exposed to ambient air. By using infrared spectroscopy and X-ray photoelectron spectroscopy we demonstrate that airborne hydrocarbons adsorb on graphitic surfaces, and that a concurrent decrease in the WCA occurs when these contaminants are partially removed. Our findings indicate that graphitic surfaces are more hydrophilic than previously believed, and suggest that previously reported data on the wettability of graphitic surfaces may have been affected by unintentional hydrocarbon contamination from ambient air.

It is generally accepted that graphitic surfaces, such as supported graphene and graphite, are hydrophobic and their water contact angles (WCAs) are in the range of 80° - 90°. In this talk, I will show that freshly prepared Cu-supported graphene and graphite surfaces are in fact hydrophilic with a WCA of ca. 44° and 64°, respectively [1]. The WCA of these surfaces increase when they are exposed to ambient air. By using infrared spectroscopy and X-ray photoelectron spectroscopy we demonstrate that airborne hydrocarbons adsorb on graphitic surfaces, and that a concurrent decrease in the WCA occurs when these contaminants are partially removed. Our findings indicate that graphitic surfaces are more hydrophilic than previously believed, and suggest that previously reported data on the wettability of graphitic surfaces may have been affected by unintentional hydrocarbon contamination from ambient air.