Pre-stabilized reduced graphene oxide by ammonia as carrier for Ni(OH)2 with excellent electrochemical property

Abstract

An advanced electrochemical pseudocapacitor material based on reduced graphene oxide and nickel hydroxide (rGO&Ni(OH)2) was prepared by an easy process where ammonia acted as a pre-stabilizer that could be easily removed. The results showed that the agglomeration and re-stacking of rGO could be effectively prevented, resulting in few-layer rGO nanosheet with high specific surface area of 891.22 m2/g which could supply large available area for loading nanoparticle. After the incorporation of Ni(OH)2 nanoparticle, the rGO&Ni(OH)2 composite owned excellent electrochemical performance thanks to effective prevention of agglomeration and re-stacking of rGO with large size of the sp2 domain, no residual of pre-stabilizer of ammonia, and tight contact between rGO and Ni(OH)2. Specifically, the rGO&Ni(OH)2 electrode exhibited excellent stability at scan rates from 100 to 300 mV/s. A high specific capacitance of 1,008 F/g was obtained at high current density of 42 A/g in 6 mol/L KOH aqueous electrolyte, and the specific capacitance demonstrated good rate capability. Moreover, rGO&Ni(OH)2 electrode showed a long cycle life, retaining 74 % specific capacitance after 2,000 cycles at current density of 6 A/g. The advantages of easy process and excellent electrochemical property suggested great potential application of rGO&Ni(OH)2 in supercapacitors.