Nanotechnology-Enabled Sensors

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terpret more complex behavior of electrochemical interactions. The nature
of the double layer changes if the electrodes are coated with nanomaterials
or nanomaterials are deposited during the electrochemical process. The effects
of nanostructured thin films on the surface of electrodes and the interactions
which occur at their surface are prominent as they are located
within the double layers.
Fig. 3.28 shows the cyclic voltammetry of electrodes made of polyaniline
nanofibres (which is a conductive polymer) that was obtained on a
three-electrode system in 1 M HCl solution containing 1 M NaCl. 18 The
scanned potential started from 0.5 to –0.5 V versus saturated Ag/AgCl reference
electrode with a scan rate of 10 mV/s. In the potential range of –0.5
to 0.5 V two cathodic peaks (P1 and P2) are observed. The value of P1 diminished
in successive scan cycles, while P2 increased. The cyclic voltammogram
of polyaniline nanofibres also exhibits two anodic peaks, P3
near 0.15 V and P4 near 0.3 V. Similar to the two cathodic peaks, P3 diminished
in the sequence scans while P4 increased. Such a tendency can be
ascribed to possible changes of the layer structure during continuous
potential cycling.
Fig. 3.28 Cyclic voltammograms of PANI nanofibres. Curves 1–5 correspond to
different scan cycles. The scan rate is 10 mV/s. Reprinted with permission from
the Institute of Physics Journals publications. 18
3.4.8 An Example: Stripping Analysis
3.4 Electrical Transducers
In stripping analysis, analyte from a diluted solution is adsorbed into a
thin film of Hg or other electrode material, usually by electro-deposition.
The electroactive species is then striped from the electrode by reversing
the direction of the voltage sweep. Current measured during the oxidative