(515a) Effect of Hydrocarbon Contamination on the Electrochemical Activity and Double Layer Capacitance of Graphitic Carbons

For nearly eighty years, graphitic carbons have been considered as hydrophobic. However, recent works in our labs showed that graphite and graphene are much more hydrophilic than previously thought. Since the water-graphitic interface is critical to many important applications including electrodes, adsorbents, catalyst support, and solid lubricants, this unexpected finding could completely change the way graphitic materials are made, modeled and modified. In this presentation, we will discuss on the intrinsic water wettability of graphitic carbons and its implications. First, our recent experimental results, e.g., contact angle, XPS, ATR-FTIR and ellipsometry, will be presented showing that pristine graphene and graphite are mildly hydrophilic and airborne hydrocarbons make the surfaces appear to be hydrophobic. Second, these results are further rationalized by analyzing the change in surface energy of the graphitic surfaces before and after hydrocarbon contamination. Third, implications of contamination will be illustrated through comparing the electrochemical activity and double layer capacitance of pristine and contaminated graphite. Lastly, future research directions to address a few important unanswered questions will be presented.