MnO_2 nanoparticles decorated on electrophoretically deposited graphene nanosheets for high performance supercapacitor

摘要

Composite of manganese dioxide and electrochemically reduced graphene oxide (MnO_2/ERGO) was prepared and investigated as active material in supercapacitor. In order to synthesize the nanocomposite, a thin film of graphene oxide (GO) was formed by elec-trophoretic deposition (EPD) technique from an aqueous dispersion of GO on stainless steel (SS). GO/SS was electrochemically reduced to form ERGO. Two-step potential method was used to deposit MnO_2 on ERGO/SS. MnO_2 nanoparticles with dimensions in the range of 40-70 nm were formed as a uniform coating on ERGO/SS. Specific capacitance of MnO_2/ ERGO/SS is 392 F g~(-1) at current density of 1 A g~(-1) in 0.5 M Na_2SO_4, which was higher than 159 F g~(-1) for ERGO/SS. Also, MnO_2/ERGO/SS shows higher power and energy densities than ERGO/SS. Due to unique structure of prepared MnO_2/ERGO nanocomposite, the capacitive behavior of ERGO is improved.