Synthesis of Nanosheet Crystallites of Ruthenate with an α-NaFeO<sub>2</sub>-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<sub>0.2</sub>RuO<sub>2</sub>·0.5H<sub>2</sub>O, with an α-NaFeO<sub>2</sub>-related crystal structure. The obtained RuO<sub>2</sub> nanosheets possessed a well-defined crystalline structure with a hexagonal symmetry, reflecting the crystal structure of the parent material. The restacked RuO<sub>2</sub> nanosheets exhibited a high pseudocapacitance of ∼700 F g<sup>−1</sup> in an acidic electrolyte, which is almost double the value of the nonexfoliated layered protonated ruthenate.