Toward the Theoretical Capacitance of RuO 2 Reinforced by Highly Conductive Nanoporous Gold

The experimental specific capacitance of ruthenium oxide (RuO2) is usually much smaller than the theoretical value due to low electron–proton transport and high rate dependence. Highly conductive nanoporous gold (NPG) can dramatically improve the capacitive performance of RuO2 when RuO2 is electroplated into NPG. The RuO2@NPG electrodes provide fast ionic conduction and excellent electron–proton transport for low rate dependence and high charge storage of around 1500 F g−1, close to the theoretical value of RuO2.