Humidity Induced Charge Migration On Single Layer Graphene Oxide Sheets

The charge migration on the surface of single layer graphene oxide (GO) sheets was investigated by scanning polarization force microscopy. Electrostatic charges were observed to transfer over 1 mu m across the insulating single layer GO sheets surface with the help of water molecules condensed from the environment. Humidity-dependent charge migration on GO sheets was visualized on the nanometer scale and the migration velocity was plotted at a relative humidity range of 10%-40%. When the relative humidity reached 50% or higher, water film would form on the whole GO sheet surface, which made the GO sheet conductive to the electrostatic charges. (C) 2014 AIP Publishing LLC.