Chemical and morphological modifications of single layer graphene submitted to annealing in water vapor

Modifications of single layer graphene transferred to SiO2/Si substrates resulting from annealing in water vapor were investigated. Near edge X-ray absorption fine structure spectroscopy evidenced graphene puckering between 400 and 500 degrees C. Synchrotron radiation based X-ray photoelectron spectroscopy showed variation of sp(2) and sp(3)C bonding configurations specially in this same temperature range. Moreover, oxygen related functionalities are formed as a result of water vapor annealing. Based on these results and complementary Raman and nuclear reaction analysis, one distinguishes three different regimes of water interaction with graphene concerning modifications of the graphene layer. In the low temperature range (200-400 degrees C), no prominent modification of graphene itself is observed. At higher temperatures (400-500 degrees C), to accommodate newly formed oxygen functionalities, the flat and continuous sp(2) bonding network of graphene is disrupted, giving rise to a puckered layer. For 600 degrees C and above, shrinking of graphene domains and a higher doping level take place. (C) 2017 Elsevier B.V. All rights reserved.