Novel green synthesis of graphene oxide-manganese dioxide using solution plasma process for energy storage

Abstract

Graphene oxide-manganese dioxide (GO-MnO2) forms an interesting family of nanocomposites that have been widely studied and applied to many electrochemical applications, including supercapacitors. However, a number of reported preparation methods still suffer several disadvantages, including complex preparation, long synthesis time, and detrimental effects on the environment as a result of excessive use of chemicals. In contrast, solution plasma process (SPP) offers a simple method that can be used to synthesize nanomaterials with minimal use of chemical reagents and short preparation time under ambient processing conditions. This work demonstrated that SPP-based preparation of the GO-MnO2 composite can be achieved. Moreover, the SPP regime was found to enable interaction between the Mn ions and the exfoliated GO sheets, with the capability of upscaling the preparation. The highest specific capacitance of the GO-MnO2 composite was obtained when only 10 min of SPP discharge time was used, resulting in the specific capacitance of 218 F g−1 at a scan rate of 5 mV s−1 in 1 M Na2SO4 aqueous electrolyte solution. This method provides a facile in situ approach to deposit MnO2 onto the GO sheets and could offer a promising, green alternative strategy to prepare similar electrode materials for other applications.