Controlling hydrophilicity and electrocatalytic properties of metallic hexacyanoferrates/conducting polymers hybrids for the detection of H2O2

Abstract

Prussian blue was incorporated into a matrix of an electronic conducting poly(5-amino-1-naphthol) to create a hydrophilic inorganic/organic hybrid material able to reduce H2O2 at 0.00V vs Ag/AgCl/Cl−sat in a medium containing Prussian blue blocking cations. The measured sensitivity was (400±30)μA cm−2mmol−1L with a detection limit of (8±3)μmolL−1, a response time of (2.4±0.5)s and a linear range up to (0.7±0.1)mmolL−1. Compared with a matrix where the inorganic material was electrodeposited alone on electrode, UV–vis spectroscopy suggested that the Prussian blue structure in contact with the conducting polymer matrix was additionally oxidized at OCP, indicating an electronic interaction between the components. The contact angle measurements and the electrochemical experiments demonstrated that the type of conducting polymer directly affected the hydrophilicity and electrocatalytic properties of the resulting hybrid material. For the metallic hexacyanoferrate synthesized into a hydrophilic conducting polymer, such as poly(5-amino-1-naphthol), the generated hybrid was also hydrophilic. For the hydrophilic matrices, the H2O2 detection was performed not only at the superficial active sites but also in the bulk of the structure, allowing modulation of the analytical performance as a function of the amount of electrocatalyst. For the metallic hexacyanoferrate synthesized into a less hydrophilic conducting polymer, such as poly(pyrrole), the formed hybrid had decreased hydrophilicity with the H2O2 detection confined to the external active sites. In this case, the analytical performances were similar with no dependency on the amount of electrocatalyst deposited. These results suggest that the modulation of hydrophilic behavior and, consequently, the electrocatalytic properties of the hybrid materials are dependent on the type of conducting polymer used in the matrices.