Reducing and multiple-element doping of graphene oxide using active screen plasma treatments

A transparent graphene oxide layer on a non-conductive poly(ethylene terephthalate) film was treated by a new active screen plasma technology at temperatures ranging from 100 °C to 200 °C in pure hydrogen and in a gas mixture of hydrogen and nitrogen. To study the thermal reducing effects of the active screen plasma, parallel thermal annealing treatments were also carried out at the same temperatures. UV–visible absorption spectra, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and electrical properties confirmed that the graphene oxide can be effectively reduced by the active screen plasma treatments. Detailed XPS quantitative analyses have revealed that the carboxylic groups are not stable, and their amount can be decreased effectively by the active screen plasma treatments. Only about one third of the carbonyl type C O can be reduced at the same time. In addition to the reduction, simultaneous multi-element doping of GO with nitrogen from the gas supply and with Fe, Cr and Mo from the stainless steel active screen was also detected by XPS.