Effective reduction and doping of graphene oxide films at near-room temperature by microwave-excited surface-wave plasma process

The effective reduction of graphene oxide (GO) and incorporation of dopant elements on flexible soft substrates, such as plastics, polymers, papers etc. are of significant importance for energy-related devices and flexible wearable electronics. Here, we demonstrate a novel microwave-excited surface-wave plasma (MW-SWP) process to reduce insulating GO to highly conducting reduced graphene oxide (rGO) on the polyethylene terephthalate (PET) substrate as well as achieving reduction of free-standing GO paper at a near-room temperature. It is also observed that the GO coated on the both top and back surface of a PET substrate reduce simultaneously to obtain conducting rGO films. Most effective reduction was achieved using an argon-hydrogen gas mixture, whereas addition of nitrogen in the gas mixture enabled to incorporate nitrogen dopant in the rGO layers. The GO coated PET and freestanding GO films showed a sheet resistance in the range of M omega/, which reduced to an average value of 1.075 k omega/ and 134 omega/, respectively after the plasma treatment. Thus, the developed MW-SWP process can be significant to produce highly conducting rGO-based graphene films on a soft substrate as well as enabling fabrication of highly conducting freestanding rGO papers.