Partially oxidized graphene as a precursor to graphene

Solution exfoliation of graphite holds promise for large-scale bulk synthesis of graphene. Non-covalent exfoliation is attractive because the electronic structure of graphene is preserved but the yield is low and the lateral dimensions of the sheets are small. Chemical exfoliation via formation of graphite oxide is a highly versatile and scalable route but the covalent functionalization of graphene with oxygen significantly alters the properties. Here, we report a new method for large-scale facile synthesis of micron-sized partially oxidized graphene (POG) sheets with dramatically improved electronic properties compared to other solution-phase exfoliated graphene. Due to low initial oxygen content (∼12%), POG requires only mild annealing (<300 °C) to achieve a sheet resistance of 28 kΩ sq^-1 at the neutrality point, only a factor of ∼4 larger than the intrinsic sheet resistance of pristine graphene (∼6 kΩ sq^-1) and substantially lower than graphene exfoliated by other methods. Such a partial oxidation approach opens up new promising routes to solution based high-performance, low temperature, transparent and conducting graphene-based flexible electronics.