Ultrasonic assisted synthesis of Ni3(VO4)2-reduced graphene oxide nanocomposite for potential use in electrochemical energy storage.

Abstract

In the present study, Ni3(VO4)2-reduced graphene oxide (NV/RGO) nanocomposite was synthesized for energy storage purpose. To this end, a mixture containing RGO nanosheets, Ni (CH3COOH)2 and Na3VO4 mixture was prepared under probe-type ultrasonic irradiation with frequency of 20KHz and the optimized power of 100W. The Raman and energy-dispersive X-ray spectroscopies confirmed the presence of RGO nanosheets, nickel and vanadium elements in the NV/RGO, respectively. In addition, field emission-scanning electron microscopy (FESEM) data showed the formation of the NV nanoparticles on the RGO nanosheets. NV/RGO nanocomposite was pasted on nickel foam (NF) and its performance was investigated in energy storage using a three-electrode cell containing 6M KOH. In cyclic voltammogram of NV/RGO/NF, redox peaks for Ni (II)/Ni (III) with intensities higher than that for NV/NF were observed which confirms the synergistic effect of RGO on the performance of NV. Chronopotentiometry data revealed that the NV/RGO/NF electrode exhibits high capacity of 117.22mAhg-1 at 2Ag-1. Electrochemical impedance spectroscopy also demonstrated an improvement in the electrical conductivity and electrochemical behavior of NV/RGO/NF nanocomposite compared to the RGO/NF and NV/NF. Furthermore, NV/RGO/NF electrode reserved about 88% of its initial capacity after 1000th potential cycle at 50mVs-1. Overall, the results of our study suggest that the NV/RGO nanocomposite prepared in the presence of ultrasonic irradiation might be regarded as a suitable active material for energy storage systems.