Growth of zinc cobaltate nanoparticles and nanorods on reduced graphene oxide porous networks toward high-performance supercapacitor electrodes.

A type of composite network constructed from zinc cobaltate (ZnCo 2 O 4 ) nanoparticles and nanorods on reduced graphene oxide (rGO) nanosheets has been prepared by a facile hydrothermal method. Transmission electron microscope results reveal that the rGO nanosheets are covered by ZnCo 2 O 4 nanoparticles evenly due to the abundant surface functional groups on surface of original GO, and supported by some cross-linked ZnCo 2 O 4 nanorods in the entire structures. With a rational combination, the composite networks present a meso-/macroporous architecture with a larger specific surface area than those of pristine ZnCo 2 O 4 nanorods. As expected, the prepared ZnCo 2 O 4 /rGO electrode exhibits improved electrochemical performances, which shows a high specific capacitance (626 F g −1 at 1 A g −1 ), excellent rate capability (81% retention of the initial capacitance at 30 A g −1 ), and long-term cycling stability (99.7% retention after 3000 cycles at 10 A g −1 ). Such remarkable electrochemical performances of ZnCo 2 O 4 /rGO electrode can be due to the effective pathways for both electronic and ionic transport in these porous networks. [ABSTRACT FROM AUTHOR]