Formation of graphane and partially hydrogenated graphene by electron irradiation of adsorbates on graphene

We report the formation of graphane and partially hydrogenated graphene by electron irradiation of graphene having chemisorbed H2O and NH3. Graphane is formed by the irradiation of graphene that is mechanically exfoliated onto SiO2 substrates in air at a relative humidity of 50%. Partially hydrogenated graphene is formed by the irradiation of graphene that is heated to remove adsorbates and then exposed to H2O or NH3 gases. We propose that hydrogenation is due to H+ ions and H radicals produced by the fragmentation of H2O and NH3 adsorbates by impact with backscattered and secondary electrons. This effect could be used as a technique for writing graphane and partially hydrogenated graphene nanostructures on graphene using electron-beam lithography. (C) 2010 Elsevier Ltd. All rights reserved.