Synthesis of Nanosheet Crystallites of Ruthenate with an α-NaFeO₂-Related Structure and Its Electrochemical Supercapacitor Property

Unilamellar crystallites of conductive ruthenium oxide having a thickness of about 1 nm were obtained via elemental exfoliation of a protonic layered ruthenate, H_0.2RuO₂·0.5H₂O, with an α-NaFeO₂-related crystal structure. The obtained RuO₂ nanosheets possessed a well-defined crystalline structure with a hexagonal symmetry, reflecting the crystal structure of the parent material. The restacked RuO₂ nanosheets exhibited a high pseudocapacitance of ∼700 F g⁻¹ in an acidic electrolyte, which is almost double the value of the nonexfoliated layered protonated ruthenate.