MADRID Rossana Elena
congresos y reuniones científicas
Multi-nanostructured and auto-regenerative sensor for H2O2 quantification using chronoimpedance as transduction method
Seminario; II International Seminar of Industrial Innovation in Electrochemistry; 2016
Hydrogen peroxide (H2O2) is a small, membrane-permeable molecule that plays an important role in industry such as pharmaceutical, mining, environmental and food. Biosensors, which are sensors with immobilized biological material, can be used in order to detect the presence of H2O2. However, these electrodes showed many disadvantages related to their stability and activity degradations of immobilized material. Therefore, there are increasing attempts to develop non-enzymatic sensors constructed from nanostructured materials. Prussian Blue (PB) is well known as one of the first reported mixed-valence transition metal hexacyanometalates with the formula of Fe4III[FeII(CN)6]3. The reduced form of PB, Prussian white (PW), has the peculiar characteristics of being able to catalyze the electrochemical reduction of hydrogen peroxide at low potentials, and this is crucial for the application of a sensor in real samples avoiding the interference from coexisting substances. In the present work, we used a gold electrode with an area of 1 cm2, in which we electrodeposited an iridium oxide film (EIROF). The formation of EIROF diminishes significantly the impedance [1]. Over this electrode we deposited Prussian Blue nanoparticles (PBNPs) [2] by drop casting. These nanoparticles showed a great auto-regeneration capacity and a strong adherence to the electrode. The presence of these nanoparticles resulted in a 2-fold decrease in the electrode impedance, which can be attributed to a higher electron transfer capacity, causing a reduction in the charge transfer resistance and to the increase in surface area. The H2O2 concentration was detected using the cronoimpedancimetric technique [3]. Making use of the percent module normalization (PMN) [3], the frequency value at which the highest response in the impedance magnitude (Z) and phase (phi) was determined. The chosen frequencies were 0.4 for Au+PBNPs and 10 Hz for Au-EIROF+PBNPs. The -0.2 V polarization was chosen based on the CV evaluation when adding 3 different concentrations of H2O2, while the 0 V measurement was carried on considering the best way to avoid the common interfering species. Real time measurements were performed while H2O2 was added to the bulk within a concentration range of 0-6 mM.