Ruthenium nanoparticles-modified reduced graphene prepared by a green method for high-performance supercapacitor application in neutral electrolyte

Abstract

Here, we report a one-pot preparation method of a ruthenium-based reduced graphene oxide hybrid (Ru_nano-based RGO). The synthesis is based on a single step for the reduction of Ru³⁺ (RuCl₃) into Ru nanoparticles, and graphene oxide (GO) into reduced graphene oxide (RGO) without the use of any reducing agent. The structure of the hybrid material was ascertained using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and high resolution transmission spectroscopy (HRTEM). The change in pH of the synthesis media resulted in different structures and morphologies. A mixture of Ru and RuO₂ (3 : 2) was obtained at pH 8.0, while only Ru-nanoparticles were obtained at pH 4.0. The supercapacitor performance of the hybrid was investigated in a neutral electrolyte, 1.0 M NaNO₃, in a three-electrode setup. Ru_nano-based RGO prepared at pH 8 exhibited a maximum specific capacitance of 270 F g⁻¹ (238.5 mF cm⁻²), and maximum energy and power densities of 15 W h kg⁻¹ and 76.4 kW kg⁻¹, respectively. The proposed supercapacitor has a stable potential window up to 1.1 V with very good cycling stability over 5000 cycles at 24 A g⁻¹.