Zeolitic imidazolate framework derived ZnCoO hollow tubular nanofibers for long-life supercapacitors.

Uniform one-dimensional metal oxide hollow tubular nanofibers (HTNs) have been controllably prepared using a calcination strategy using electrospun polymer nanofibers as soft templates and zeolitic imidazolate framework nanoparticles as precursors. Utilizing the general synthesis method, the ZnO HTNs, CoO HTNs and ZnCoO HTNs have been successfully prepared. The optimal ZnCoO HTNs, as a representative substance applied in supercapacitors as the positive electrode, delivers a high specific capacity of 181 C g at a current density of 0.5 A g, an excellent rate performance of 75.14% and a superior capacity retention of 97.42% after 10 000 cycles. Furthermore, an asymmetric supercapacitor assembled from ZnCoO HTNs and active carbon also shows a stable and ultrahigh cycling stability with 95.38% of its original capacity after 20 000 cycle tests.