Synthesis of graphene via in-liquid discharge plasma: A green, novel strategy and new insight

The synthesis of reduced graphene oxide (rGO) in an efficient manner has attracted considerable attention because of extensive applications in electronics, composite materials, and energy-storage devices. Here we propose a novel strategy for reducing graphene oxide (GO) by microwave discharge plasma in liquid (MDPL). This method is of fast reduction, high reactivity, and low temperature, which is suitable for efficient graphene preparation. The XPS results show that MDPL reduces the initial oxygen content of GO by more than 60%. Electrical characterization of rGO shows an enhanced conductivity of 70 S/m. The atomic hydrogen and energetic electrons in MDPL can effectively facilitate the deoxygenation and the recovery of pi-conjugation of GO. As a supercapacitor electrode, plasma-treated rGO can deliver a gravimetric capacitance of 164.9 F/g at a scan rate of 5 mV/s. To summarize, our study paves the way towards the mild, eco-friendly, and efficient production of graphene.