High-performance supercapacitors of ruthenium-based nanohybrid compounds

Hybrid capacitor materials exhibit good electrochemical performance because they possess the advantages of both electrical double-layer capacitors (EDLCs) and pseudocapacitors (PCs). Here, ruthenium nanohybrid compounds (Ru-com) are synthesized with hydrous ruthenium oxide (RuO2·H2O), EDLCs, and ruthenium nanoparticles capped by cysteine (Ru-cys), which are PCs. The morphologies and structures of Ru-com, RuO2·H2O, and Ru-cys are confirmed by several characterization methods. The electrochemical performances are investigated by cyclic voltammetry, galvanostatic charging-discharging, and electrochemical impedance spectroscopy. The Ru-com exhibits a specific capacitance of 797.7 A g−1 in 0.5 M H2SO4 electrolyte at a scan rate of 10 mV s−1, which is much larger than the specific capacitance of its precursors, due to the synergistic effect of the reversible faradaic redox process and facilitated proton and electron transfer processes. In addition, the Ru-com not only shows a better rate capability than Ru-cys but also exhibits a better electrochemical stability than RuO2·H2O owing to the mutual modification of its components. •Ru based hybrid nanocompounds with both RuIV and Ru0 part were synthesized.•Ru-com shows greatly improved specific capacitance of 797.7 F g−1.•Ru-com has the merits of electrical double-layer capacitors and pseudocapacitors.