In the second step, ultrathin Co shell is conformably deposited
on porous Co3O4 nanowires core with the help of electro-
deposition method (Fig. 1). The morphology of the as-prepared
samples is characterized by FESEM. It is seen that the Co3O4
nanowires with sharp tips are grown uniformly on the substrate
forming array structure. The low magnification FESEM image
(Fig. 2b) demonstrates the large-area growth of Co3O4 nanowire
arrays. After electro-deposition of Co (Fig. 2c), note that each Co3O4
nanowire is interconnected by thin Co shell forming composite
Fig. 1. Synthesis process of Co3O4@Co core/branch nanowires arrays.
140 M. Chen et al. / Materials Research Bulletin 84 (2016) 139–144