High Performance Supercapacitors from Novel Metal-Doped Ceria-Decorated Aminated Graphene

Herewith we are reporting a half-cell study of ceria electrode material made by uniform doping of silver and platinum nanoparticles for high performance supercapacitor applications. The hydrothermally synthesized electrode material had 5-7 nm size doped ceria particles decorated on a graphene sheet. The electrodes were prepared by dip coating. The measured specific capacitance for the neat Gr-CeO2 electrode was found to be 208 F g(-1) at 1 A g(-1) current density. Doping with silver and platinum, a large increase in specific capacitance was observed. Silver doping gave 1017 F g(-1) specific capacitance at 1 A g(-1) current density, a 5-fold increase, while platinum doping gave a 10-fold increase in specific capacitance, i.e., 1987 F g(-1) at 1 A g(-1) current density. The maximum energy and power density obtained were 41 kW kg(-1) and 400 Wh kg(-1) respectively, at 1 A g(-1) current density for the Gr-CeO2-Pt electrode. The significant increase in specific capacitance was argued on the basis of enhancement in electrical conductivity and improvement in the electron transfer between electrodes and electrolyte. The stability check of the electrodes was performed by charging/discharging cycles at 5 A g(-1) current density in 6 M KOH solution. In a 1000 cycle study, exceptional high specific capacitance was found in the initial few charging/discharging cycles. The constant capacitances of about 600 and 206 F g(-1) at 5 A g(-1) current density for Gr-CeO2-Pt and Gr-CeO2-Ag, respectively, were found after 500 cycles, suggesting ceria-doped materials will be an excellent candidate for new generation supercapacitor applications.