Asymmetric metal oxide pseudocapacitors advanced by three-dimensional nanoporous metal electrodes

We report a novel RuO2–NPG//Co(OH)2–NPG asymmetric supercapacitor with a high specific capacitance and a wide potential window in which bifunctional nanoporous gold is used as both the highly conductive supports of the pseudocapacitive oxides and the 3D current collectors in the device. The RuO2–NPG and Co(OH)2–NPG electrodes can reach specific capacitances of 1300 F g−1 and 1800 F g−1, respectively, which provide comparatively high specific capacitances in relation to metal oxide/carbon electrodes, giving rise to an asymmetric oxide pseudocapacitor with a large capacitance of ∼350 F g−1, high working voltage of 1.6 V and an ultrahigh energy density of ∼120 W h kg−1.