▎ 摘　　要

Hollow NiCo2O4 nanoparticle/graphene composite was firstly fabricated by a template-free method via a hydrothermal route combined with a two-step annealing treatment in N-2 and air atmosphere, respectively. The structure and morphology of the composite were studied by XRD, XPS, FE-SEM and TEM. As a supercapacitor electrode material, the hollow NiCo2O4 nanoparticle/graphene composite showed high specific capacitance (1238 F g(-1) at 1 A g(-1)) and excellent cycle stability. The excellent electrochemical performance may be ascribed to the synergistic effect between the conductive graphene and the hollow structure of NiCo2O4 nanoparticle. This work showed that the hollow NiCo2O4 nanoparticle/graphene composite should be a promising electrode material for supercapacitors. (C) 2016 Elsevier B.V. All rights reserved.