Tailoring of RuO 2 nanoparticles by microwave assisted “Instant method” for energy storage applications

Abstract

RuO 2 nanoparticles are synthesized by Instant method using Li 2CO 3 as stabilizing agent, under microwave irradiation at 60 °C and investigated for the anodic oxygen evolution reaction (OER) and for their supercapacitance properties in 0.5 M H 2SO 4 medium. Structural and morphological characterizations of RuO 2 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 RuO 2 nanoparticles with mean diameter of ca. 1.5 nm. Analysis on as prepared material indicates the structural formula as [RuO 2·2.6H 2O] 0.7H 2O with low crystallinity. The influence of annealing temperature on RuO 2 is studied in light of electrocatalytic activity for oxygen evolution reaction (OER) and capacitance. Electrochemical performances of RuO 2 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 RuO 2 is found to be consistent with the electrical energy supplied to the catalyst. The cyclic voltammogram of RuO 2 exhibits the typical capacitance behavior with highly reversible nature. The specific capacitance of hydrous RuO 2 is found to be 737 F g −1 at the scan rate of 2 mV 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 RuO 2. The present study shows the potential method to synthesize rapid and uniform nano particles of RuO 2 for water electrolysis and supercapacitors.