Microstructural and electrochemical characterization of RuO2/CNT composites synthesized in supercritical diethyl amine

A simple and efficient route to decorate carbon nanotubes (CNTs) with nanocrystalline RuO2 has been developed. In this method, RuCl3 · 3H2O was oxidized into RuO2 by oxygen in supercritical diethyl amine, and the produced RuO2 deposited on CNTs, resulting in RuO2/CNT nanocomposites. The as-prepared composites were structurally and morphologically characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy (TEM). TEM images showed that RuO2 nanoparticles attached on CNTs had uniform shape and a narrow particle size distribution. The loading content and the size of RuO2 particles on CNTs could be tuned by changing the mass ratio of RuCl3 · 3H2O/CNT. Electrochemical measurements by cyclic voltammetry demonstrated a substantial increment of the specific capacitance of CNTs due to a pseudocapacitance originated from the deposited RuO2 nanoparticles.