Tailoring of RuO2 nanoparticles by microwave assisted "Instant method" for energy storage applications

RuO2 nanoparticles are synthesized by Instant method using Li2CO3 as stabilizing agent, under microwave irradiation at 60 degrees C and investigated for the anodic oxygen evolution reaction (OER) and for their super-capacitance properties in 0.5 M H2SO4 medium. Structural and morphological characterizations of RuO2 are investigated by in situ X-ray diffraction (XRD), thermogravimetric analysis (TG-DTA), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDS) and Raman spectroscopy. The TEM images of as prepared material show the uniform distribution of RuO2 nanoparticles with mean diameter of ca. 1.5 nm. Analysis on as prepared material indicates the structural formula as [RuO2 center dot 2.6H(2)O] 0.7H(2)O with low crystallinity. The influence of annealing temperature on RuO2 is studied in light of electrocatalytic activity for oxygen evolution reaction (OER) and capacitance. Electrochemical performances of RuO2 electrodes are followed by current-potential curves, galvanostatic charge-discharge cycles and evolved oxygen measurements. The amount of oxygen gas evolved during the OER by the crystalline RuO2 is found to be consistent with the electrical energy supplied to the catalyst. The cyclic voltammogram of RuO2 exhibits the typical capacitance behavior with highly reversible nature. The specific capacitance of hydrous RuO2 is found to be 737 Fg(-1) at the scan rate of 2 my s(-1), by the balanced transport of proton through the structural water and electron transport along dioxo bridges, which makes a suitable material for energy storage. The specific capacitance decreases with increase in the crystallinity of RuO2. The present study shows the potential method to synthesize rapid and uniform nano particles of RuO2 for water electrolysis and supercapacitors. (C) 2010 Elsevier B.V. All rights reserved.