Hierarchical NiCo2O4 nanostructured arrays decorated over the porous Ni/C as battery-type electrodes for supercapacitors.

The hierarchical nanoarrays NCO NWs /NC and NCO NSs /NC were prepared by a two-step fabrication process. The porous NC substrate derived by Ni-MOF uniformly was as "favorable skeleton", which could provide large surfaces for the growth of nanoarrays. Two different morphologies NiCo 2 O 4 nanoarrays were vertically grown on the porous NC substrate through in-situ growth methods. The introduction of urea could induce the formation of the hierarchical well-organized NiCo 2 O 4 nanowires arrays. Without urea, the NiCo 2 O 4 nanosheets arrays were obtained. This fabrication strategy utilizing the porous NC substrate as the skeleton to construct the hierarchical structure not only favors the interface electron transfer, but also improves specific capacitance for the NiCo 2 O 4 nanoarrays. [Display omitted] • The porous NC substrate derived from Ni-MOF provides large specific surface and good conductivity for NiCo 2 O 4 nanoarrays. • The hierarchical architecture of NiCo 2 O 4 /NC nanoarrays as battery-type supercapacitors was constructed. • The hierarchical electrode with the NiCo 2 O 4 nanowires arrays grown on "favorable skeleton" NC (NCO NWs /NC) exhibits better electrochemical performance. The rational construction of hierarchical electrode materials has always been an attractive strategic development in energy storage. In this paper, the porous Ni/C (NC) substrate, which is derived from Ni metal–organic frameworks (Ni-MOFs), is served as the conductive skeleton on Ni foam (NF) for supporting two different morphologies NiCo 2 O 4 nanostructure arrays (NiCo 2 O 4 /NC). The hierarchical layered nanomaterial utilizes the porous NC substrate as "favorable skeleton" for electron transfer and is coupled to vertical well-organized NiCo 2 O 4 nanoarrays to improve specific capacitance of composites. Benefits from the advantages of hierarchical layered structure, the electrochemical properties of as-constructed NiCo 2 O 4 /NC with two different morphologies were better than those of pure NiCo 2 O 4 prepared under the same conditions. Moreover, the optimized NiCo 2 O 4 nanowires arrays on NC substrate (NiCo 2 O 4NWs /NC) electrode acquire prominent specific capacitance of 1945.9 F g−1 (270.3 mAh g−1) at 1 A g−1 and good rate performance. Additionally, the assembled asymmetric device by NiCo 2 O 4NWs /NC and carbon nanotube (CNT) displays a high energy density of 58.31 Wh kg−1 at a power density of 749.7 W kg−1, as well as good cyclic stability. The remarkable properties manifest that the hierarchical NiCo 2 O 4NWs /NC electrode has a good prospect in electrochemical applications. [ABSTRACT FROM AUTHOR]