Strongly coupled nickel boride/graphene hybrid as a novel electrode material for supercapacitors

Herein, we report the preparation of strongly coupled nickel boride/reduced graphene oxide (Ni2B/RGO) hybrid via simultaneous chemical reduction of nickel dichloride (NiCl2 center dot 6H(2)O) and graphene oxide (GO) in one pot using NaBH4 as reductant under nitrogen atmosphere. The Ni2B/RGO hybrid is demonstrated to be an excellent and novel electrode material for supercapacitors. The specific capacitance of Ni2B/RGO hybrid annealed at an optimized temperature of 200 degrees C (Ni2B/RGO-200) can reach 1073.4 Fg(-1) at a current density of 1 A g(-1) in 6 M KOH solution. Meanwhile, the hybrid supercapacitor (HSC) device fabricated using Ni2B/RGO-200 as positive electrode and activated carbon (AC) as negative electrode delivers a high energy density of 22.1 Wh kg(-1) at a power density of 724.9Wkg(-1). After 2500 chargedischarge cycles at a current density of 6 A g(-1), the HSC can still retain 72.4% of its initial performance. The excellent capacitor performance of Ni2B/RGO-200 hybrid should not only attribute to the adequate electrochemical reaction active sites of Ni2B particles, but also the enhanced electron transfer rate and superior electrochemical stability of graphene. (C) 2017 Elsevier B.V. All rights reserved.