In-situ fabrication of Co foam@Co 3 O 4 porous nanosheet arrays for high performance supercapacitors

A facile Co foam@Co3O4 porous nanosheet arrays (CPNA) has been synthesized via an in-situ oxidization reaction and there are tiny pores with diameter of 5 ± 2 nm that evenly distribute on the nanosheet with thickness of 3 ± 1 nm. The as-prepared Co foam@CPNA sample owns an ultrahigh specific capacitance of 2585 F g-1 at 5 mV s−1 and the resistance is only 1.09 Ω. It also shows a remarkable long-term stability of 77.5% capacitance retention over 20,000 charge/discharge cycles at 5 A g−1. The results suggest that the in-situ growth of Co3O4 porous nanosheet arrays on the Co foam plays an important role in its excellent electrochemical performance.