Alcohol addition improves the liquid-phase plasma process for “Green” reduction of graphene oxide

Graphene oxide (GO) and reduced graphene oxide (r-GO) continue to attract considerable research due to their applicability in many academic and industrial fields. Here, we report a liquid-phase plasma approach with fast reduction and high reactivity for directly converting GO to r-GO at mild temperatures. The liquid-phase plasma process is at the forefront, and it is a strong candidate for facilitating large-scale applications of GO and r-GO. In this work, using methanol as an additive rather than other hazardous reducing agents, the results demonstrated that methanol could provide more hydrogen radicals (·H) to improve the reduction process of the liquid-phase plasma. Meanwhile, the ·CH2, ·CH, ·C, ·C2, ·OH, ·H, ·O were formed during discharge, suggesting that the collision of energetic electrons in plasma with methanol and water, which subsequently removes oxygen-containing functional groups and restores the π-conjugated structure in GO through a radical process. The analytical results revealed that r-GO has been successfully reduced by liquid-phase plasma. In conclusion, our findings can provide underlying insights into liquid-phase plasma treatment for GO reduction. •Microwave liquid-phase plasma approach for graphene oxide reduction.•Energetic electrons and ·H for the deoxygenation and sp2 carbon restoration.•Plasma and methanol in combination results in higher ·H reduction rates.•Future studies of simultaneous reduction and defect healing: create a paradigm.