Prior to the investigation of the sensitivity of the sensor to
hydrogen peroxide, the redox properties of the sensing layer
have been characterized in a phosphate buffer by applying a
sweep potential between 0–500 mV with respect to the SCE.
Fig. 3 shows a part of the cyclic voltammogram of the redox
active layer recorded at a sweep rate of 100 mV/s. The redox
peaks, typical for [Os2þ]/[Os3þ], are clearly visible. After
deposition of the Nafion layer, the cathodic and anodic peaks
diminished (dashed lines in Fig. 3), resulting from a slight
reduction of the redox properties of the Os-PVP.
The response of the sensor having the Nafion layer on the
gate to hydrogen peroxide has been studied by adding a
small amount of the stock hydrogen peroxide solution.
During measurement, a dc reducing current of 25 nA has
been applied. As can be seen in Fig. 4, when the hydrogen