Highly sensitive H2O2 sensor based on poly(azure A)-platinum nanoparticles deposited on activated screen printed carbon electrodes

The sensitive determination of hydrogen peroxide has broad analytical applications. In this work, a novel non-enzymatic hydrogen peroxide sensor based on Pt nanoparticles (PtNPs) electrochemically deposited on previously modified and activated screen-printed carbon electrodes (aSPCEs) was constructed. The pretreatment consisted of subjecting the electrodes to a surface activation treatment with hydrogen peroxide followed by the electrodeposition of poly(azure A) films (PAA) in a sodium dodecyl sulfate micellar aqueous solution. The PtNPs/PAA/aSPCEs were characterized by scanning electron microscope, X-Ray photoelectron spectrometry, linear scan voltammetry and electrochemical impedance spectroscopy. Linear sweep voltammograms showed that the oxidation peak potential of H2O2 shifts from ~1 V at SPCEs to ~0.1 V at PtNPs/PAA/aSPCEs. The fabricated electrodes showed excellent electrocatalytic activity towards H2O2 oxidation, making its detection possible at 0.1 V. The detection limit was 51.6 nM, which is significantly lower than other modified electrodes found in the literature, and the linear range ranging from 0 to 300 μM. The proposed electrode was successfully applied to the determination of H2O2 in real samples in different areas. Additional experiments against common interfering agents (ascorbic acid, dehydroascorbic acid, glucose, salicylic acid, among other compounds) showed no increase in the current signal and only in the case of ascorbic acid a small interference, not greater than 10% is observed, which indicates high specificity of the sensor. These electrodes open up alternative avenues for the development of highly sensitive, robust and low cost electrochemical H2O2 sensors for field tests