One-Step Green Hydrothermal Synthesis of Few-Layer Graphene Oxide from Humic Acid

The conventional synthesis route of graphene oxide (GO ), based on Hummers method, suffers from explosion risk, environmental concerns and a tedious synthesis process, which increases production costs and hinders its practical applications. Herein, we report a novel strategy for preparing few-layer graphene oxide (GO ) from humic acid via simple hydrothermal treatment. The formation of GO is mainly attributed to the hydrolysis, oxidation and aromatization of humic acid under hydrothermal conditions. The as-prepared few-layer GO has typical morphology (thin and crumpled sheets with the thickness of ~3.2 nm), crystal structure (a Raman I /I ratio of 1.09) and chemical composition (an X-ray Photoelectron Spectroscopy (XPS) O/C atomic ratio of 0.36) of few-layer GO . The thermally reduced GO (r-GO ) delivers considerable area capacitance of 28 µF·cm , high rate capability and low electrochemical resistance as supercapacitor electrodes. The described hydrothermal process shows great promise for the cheap, green and efficient synthesis of few-layer graphene oxide for advanced applications.