Templated fabrication, characterization and electrocatalysis of cobalt hexacyanoferrate nanotubes

Cobalt hexacyanoferrate (CoHCF) nanotubes with high aspect ratio were fabricated by sequential deposition method using the porous anodic aluminum oxide (AAO) template, which was prepared by two-step anodization method. The nanotubes were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and ultraviolet/visible (UV–vis) spectroscopy. The results of XRD and X-rays energy dispersive analysis indicated that the nanotubes had a cubic structure with cell constant of a = 10.24 Ǻ and atomic ratio of Co to Fe of 3:2. The formation mechanism of CoHCF nanotubes in the inner wall of AAO template was discussed and verified by the cross-sectional SEM images. The electrochemical characteristics of CoHCF nanotubes were investigated by cyclic voltammetry and its cyclic voltammogram was characterized with two couples of redox peaks with the formal potential of 652 and 467 mV, respectively, in 0.2 M of KCl solution at a scan rate of 20 mV/s. The voltammetric results also indicated that the CoHCF nanotubes had high electrocatalytic activities toward the oxidation of ascorbic acid and dopamine compared with that of bulk prepared CoHCF sample. The methods presented in this work can be extended to fabricate nanotubes of hexacyanoferrates of other transition or rare earth metals.