Comparison of alpha-NiMoO4 nanorods and hierarchical alpha-NiMoO4@delta-MnO2 core-shell hybrid nanorod/nanosheet aligned on Ni foam for supercapacitors

摘要

Three-dimensional (3D) hierarchical alpha-NiMoO4@delta-MnO2 core-shell hybrid nanorods/nanosheets are fabricated directly on Ni foam via a two-step approach which involves hydrothermal and one-pot chelation- mediated aqueous processes. The alpha-NiMoO4 nanorods are full covered by ultrathin delta-MnO2 nanosheets and the morphological evolution process of a-NiMoO4@delta-MnO2 electrode has been investigated by scanning electron microscopy (SEM) at different time intervals. When this hybrid, along with porous Ni foam, is employed as binder-free electrode for supercapacitors, exhibiting high capacitance of 1136 F g(-1) at a current density of 2 A g(-1) and super-long cycling life with 101.9% retention rate after 5000 cyclic voltammetry cycles, which are much better than the single alpha-NiMoO4 nanorod electrode. Moreover, according to the electrochemical impedance spectroscopy (EIS) analysis, it is found that the equivalent series resistance (R-s) and charge transfer resistance (R-ct) of the hybrid electrode are 0.22 Omega and 4.03 Omega, respectively. In view of the outstanding electrochemical performance and the cost-effective fabrication process, this unique integrated nanoarchitecture would hold great promise for electrochemical energy storage. (C) 2017 Elsevier B. V. All rights reserved.