Ali A. Ensafi, Mehdi Mokhtari Abarghoui, Behzad Rezaei

A B S T R A C T
In this study, Ni2CoS4 nanoparticles were coated on the surface of graphitic carbon nitride (g-C3N4) nanosheets using a hydrothermal process. The composition and morphology of the nanocomposite thus obtained were characterized using different spectroscopic techniques. When subjected to cyclic voltammetry and constant current chronopotentiometry in alkaline media, the charge storage properties and electrochemical performance of the as-prepared Ni2CoS4@g-C3N4 nanocomposite were found to be superior not only to those of Ni2CoS4 nanoparticles and their monometallic counterparts (Co3S4@g-C3N4 and Ni3S4@g-C3N4) but also to those of g- C3N4 nanosheets, Ni1.5Co1.5S4@g-C3N4, and NiCo2S4@g-C3N4. Moreover, the Ni2CoS4@g-C3N4 nanocomposite exhibited a high charge storage capacity of 246 mAh g−1 or 2210 F g−1 at a discharge current of 1 A g−1, an excellent rate capability (over 86% retention at 40 A g−1), a high cycling stability (85% of charge storage capacity retention after 4000 charge-discharge cycles), and a high columbic efficiency of 99% at a discharge current of 40 A g−1. Based on the results obtained, such hybrid nanocomposites may be claimed to be good
candidates for use as electrode materials in energy storage devices due to their high performance at high current densities, good stability, and high columbic efficiency.

Keywords:
Ni2CoS4 nanoparticles, Graphitic carbon nitride, Electrode material, Energy storage devices