Figure 4

(a) Charge–discharge profiles of the bare vertical graphene nanosheets (VGNS)@Ni foam electrode at a current density of 200 mA g⁻¹. (b) Charge–discharge profiles of the ruthenium (Ru)-decorated VGNS@Ni foam electrode at a current density of 200 mA g⁻¹. (c) Charge–discharge profiles of Ru-decorated VGNS@Ni foam electrode with the capacity restricted to 1000 mAh g⁻¹ at 200 mA g⁻¹ current density. (d) Corresponding cycling performance with a fixed capacity of 1000 mAh g⁻¹ at 200 mA g⁻¹ current density.