High Energy/Power Supercapacitor Performances of Intrinsically Ordered Ruthenium Oxide Prepared through Fast Hydrothermal Synthesis

Abstract

A simple one-step microwave-assisted and temperature-controlled hydrothermal synthesis was applied to prepare a nanocrystalline RuO2 dispersion from an aqueous solution of RuCl3 for supercapacitive applications. The obtained RuO2 dispersions were subjected to dynamic light scattering in order to analyze the particle size distribution, whereas morphology and structural properties of the solid phase were investigated by using AFM, SEM, EDX, TEM, and XRD techniques. Ellipsoidally shaped 100-500 nm-sized compact grains, joined into highly ordered prismatic agglomerates, are observed. Two types of grains are observed: more regular ones consisting of spherical, amorphous particles of a few nanometers in size, and irregular ones made of partially crystalline 10-80 nm-sized particles. Consequently, the most dominant structure is 250-nm grains. The particles tend to join tightly across their crystalline domains, which appears responsible for the formation of prismatic shapes of several micrometers. This arraying causes high capacitive activity - specific capacitances of up to 800 Fg(-1) are registered, which negligibly depend on the charging/discharging rate. The synthesized material is of highly accessible internal structure, and is an excellent candidate for both low- and high-power applications.