Anchoring CuO nanoparticles on nitrogen-doped reduced graphene oxide nanosheets as electrode material for supercapacitors

• CuO/nitrogen-doped reduced graphene oxide (CuO/N-RGO) composites are synthesized via a facile and scalable method.
• CuO nanoparticles anchor homogeneously on the nitrogen-doped reduced graphene oxide (N-RGO) nanosheets.
• The composite of 10 mmol CuO/N-RGO shows excellent capacitive performance.

CuO/nitrogen-doped reduced graphene oxide (CuO/N-RGO) composites are prepared by refluxing in ammonia solution and low temperature annealing. The as-prepared samples have been characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The loading of CuO has been measured by using inductively coupled plasma mass spectroscopy (ICP-MS). Results reveal that the CuO nanoparticles with ∼5 nm in diameter are anchored homogeneously on the nitrogen-doped reduced graphene oxide (N-RGO) nanosheets. Their electrochemical performances for supercapacitors are investigated by cyclic voltammetry (CV), galvanostatic charge–discharge and electrochemical impedance spectroscopy (EIS). The CuO/N-RGO composite with 15.1 wt% CuO loading shows a high specific capacitance of 340 F g−1 at a charge/discharge current density of 0.5 A g−1 in 6 mol dm−3 KOH electrolyte, and with a wide potential window of 1.4 V. Importantly, 58% of capacitance is retained when the charge/discharge current density increases from 0.5 A g−1 to 5 A g−1. The capacitance retention can reach to 80% after 500 charge/discharge cycles. These findings demonstrate that the CuO/N-RGO material is a promising candidate for supercapacitor applications.