Facile synthesis of Co3O4 with different morphologies loaded on amine modified graphene and their application in supercapacitors

A simple and scalable method has been developed for the growth of Co3O4 on amine modified graphene (NH2-Gs), synthesized from the hydrothermal reaction of graphene oxide in the presence of ammonia. It shows that the relative NH3 content could alter the elemental composition and the relative percentages of functional groups in NH2-Gs, and the Co3O4 particles on the NH2-Gs with a relatively higher amount of amine groups exhibit a relatively small sizes. The obtained Co3O4/NH2-Gs can then be used as an active electrode material for supercapacitors. Among the synthesized samples, Co3O4/NH2-G(2) (the weight ratio of ammonia to GO is 5) exhibits the highest capacitive performance, 2108.4 F g(-1) at 1 A g(-1) and 1356.7 F g(-1) at 15 A g(-1), which is much higher than that of Co3O4 based materials reported previously. The electrode also has a satisfactory cycling performance with capacity retention of 64% after 800 cycles at 5 A g(-1). The enhanced electrochemical performances of Co3O4/NH2-G(2) are ascribed to the higher specific surface area, the smaller Co3O4 particle sizes, the strong interaction between Co3O4 and NH2-G(2), and the higher conductivity. The excellent electrochemical performance makes the resultant composite materials to be a promising candidate for supercapacitor electrode application. (C) 2016 Elsevier B.V. All rights reserved.