Morphology and Electrochemistry of Ruthenium/Carbon Aerogel Nanostructures

The structure−property relationships of nanostructured Ru/carbon aerogel composite materials have been evaluated. These new materials were prepared via a novel two-step metal vapor impregnation method which enables one to control the Ru loading through repetition of the process. The resulting microstructure is characterized by highly dispersed Ru particles (≈20−30 Å in diameter) attached to the carbon aerogel surface and distributed homogeneously throughout the material; the open pore structure of the carbon aerogels remains largely unaffected. Electrochemical characterization indicates that it is possible to increase the specific capacitance of the carbon aerogels in 1.0 M H 2 SO 4 from ≈100 F/g to greater than 250 F/g for samples with >50 wt % Ru due to the pseudocapacitive properties of hydrous RuO 2 . A volumetric capacitance greater than 140 F/cm 3 was observed for some samples. In addition, these materials show good cycling characteristics. Electrochemical impedance spectroscopy was unable to distinguish between double-layer capacitance and pseudocapacitance in these materials.