The initial voltammogram of the bare CNT electrode
exhibited a capacitive rectangular response in the potential window of 0.1–1.3 V.
Note that the tail-like response over 1.3 V
related to the oxidation of water. In contrast, two additional pairs
of redox peaks centered at 0.25 V and 0.80 V, respectively, were
apparent after applying the rectangular potential to the CNT electrode
(Fig. 6).