(357h) Understanding the Intrinsic Water Wettability of Graphitic Carbon

Andrew Kozbial and Lei Li

Department of Chemical and Petroleum Engineering, University of Pittsburgh, 3700 Oâ??Hara Street, Pittsburgh, PA 15261

The intrinsic water wettability of graphitic carbon, e.g., graphite, graphene and carbon nanotube, has attracted a lot of research interests in the past three years due to the recent finding that the long-established hydrophobicity of graphitic surfaces actually results from airborne hydrocarbon contamination. Due to the existence of defects, determining intrinsic water wettability of pristine graphitic carbon remains challenging. In the current study, water wettability of freshly exfoliated graphite of varying quality was studied using static, advancing, and receding water contact angle (WCA) measurements. The defect densities were characterized by Raman spectroscopy, XPS and AFM. A qualitative model is proposed to explain the effect of defects on measuring the advancing, static, and receding contact angles. Based on the model and the experimental results, the pristine graphitic carbon is mildly hydrophilic.