Morphological characteristics analysis of Polypyrrole film fabricated by electrochemical polymerization

The morphological characteristics such as surface area, thickness, and roughness of the Polypyrrole (PPy) on metal electrodes of electrochemical sensors affect sensitivity and selectivity of electrochemical sensors because the surface morphology of PPy affects reduction and oxidation of the electrodes. The PPy morphology was investigated by changing several polymerization parameters such as polymerization time, electrolytes, and metal electrodes. Indium tin oxide (ITO) or Au was used as a seed metal electrode on which PPy was electropolymerized. The electropolymerization was performed in an electrolyte, either sodium dodecyl sulfate (NaDS) or sodium dodecyl benzene sulfonate (NaDBS). A homogeneous PPy morphology was obtained on ITO electrode when NaDBS solution was used as an electrolyte, but when NaDS solution was used for polymerizing on ITO electrode, the electropolymerized PPy showed uniform surface morphology and film thickness up to l min polymerization time while further polymerization resulted in non-uniform networks like a spider web. This increases the detection surface area with identical metal electrodes of electrochemical sensors. When Au was used, neither NaDBS nor NaDS solution resulted in any morphology change of the PPy film regardless of the polymerization time. The effect of the PPy morphology on the electrochemical sensors will also be presented.