Swelling, intercalation, and exfoliation behavior of layered ruthenate derived from layered potassium ruthenate

The intercalation chemistry of a layered protonic ruthenate, H0.2RuO2.1·nH2O, derived from a layered potassium ruthenate was studied in detail. Three phases with different hydration states were isolated, H0.2RuO2.1·nH2O (n=∼0, 0.5, 0.9), and its reactivity with tetrabutylammonium ions (TBA+) was considered. The layered protonic ruthenate mono-hydrate readily reacted with TBA+, affording direct intercalation of bulky tetrabutylammonium ions into the interlayer gallery. Fine-tuning the reaction conditions allowed exfoliation of the layered ruthenate into elementary nanosheets and thereby a simplified one-step exfoliation was achieved. Microscopic observation by atomic force microscopy and transmission electron microscopy clearly showed the formation of unilamellar sheets with very high two-dimensional anisotropy, a thickness of only 1.3±0.1 nm. The nanosheets were characterized by two-dimensional crystallites with the oblique cell of a=0.5610(8) nm, b=0.5121(6) nm and γ=109.4(2)° on the basis of in-plane diffraction analysis.