Sol-gel synthesis of hydrous ruthenium oxide nanonetworks from 1,2-epoxides

摘要

Hydrous ruthenium oxide (RuO2 center dot xH(2)O) xerogels were synthesized through the addition of a 1,2-epoxide, propylene oxide, to commercial hydrated ruthenium chloride, "RuCl3 center dot xH(2)O," in ethanol. After a blue-black monolithic gel formed in 4 h, the samples were allowed to age for 24 It and were dried in ambient conditions. The dried samples were then characterized by XPS, XRD, DTA and TGA. XPS showed the Ru(3d(5/2)) peak at a binding energy of 281.7eV, corresponding to that of hydrous ruthenium oxide. XRD data revealed the synthesized material as amorphous. Heating the sample in inert atmospheres caused the complete reduction of the oxide to the zerovalent state, whereas heating the sample in air resulted in both crystalline anhydrous RuO2 and zero-valent ruthenium, depending on the method of heating. DTA traces showed an endotherm ending at 150 degrees C, corresponding to the loss of coordinated water, as well as two higher temperature crystallization exotherms when the sample was heated in both inert and oxygen-rich atmospheres. TGA runs also confirmed the complete reduction of the hydrous oxide when heated in nitrogen below 270 degrees C and the formation of anhydrous ruthenium oxide when heated in air, confirming the XRD results. (C) 2007 Elsevier Inc. All rights reserved.