MnO2 nanoparticles decorated on electrophoretically deposited graphene nanosheets for high performance supercapacitor

• Graphene oxide film was prepared by electrophoretic deposition (EPD) method.
• Reduced graphene oxide film was prepared by electrochemical reduction (ECR) method.
• Uniform size distribution of MnO2 nanoparticles was prepared by bipotential method.
• High specific capacitance of 392 F g−1 at 1 A g−1 is obtained in Na2SO4.
• The electrode reveals 87% retention of initial capacitance for 1200 cycles at 1 A g−1.

Composite of manganese dioxide and electrochemically reduced graphene oxide (MnO2/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 electrophoretic 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 MnO2 on ERGO/SS. MnO2 nanoparticles with dimensions in the range of 40–70 nm were formed as a uniform coating on ERGO/SS. Specific capacitance of MnO2/ERGO/SS is 392 F g−1 at current density of 1 A g−1 in 0.5 M Na2SO4, which was higher than 159 F g−1 for ERGO/SS. Also, MnO2/ERGO/SS shows higher power and energy densities than ERGO/SS. Due to unique structure of prepared MnO2/ERGO nanocomposite, the capacitive behavior of ERGO is improved.