Electrochemical sensor based on porous silicon/silver nanocomposite for thedetermination of hydrogen peroxide

Sensitive and selective determination of H2O2 is of great significance in biological, clinical andenvironmental and many other fields. Among several analytical techniques that have beenemployed for the determination of H2O2, electrochemical methods have received significantimportance due to their low detections limit, high selectivity and sensitivity [1]. Becauseelectrochemical reduction of H2O2 with the conventional electrodes is not effective for analyticalapplication, surface modification of the electrode is necessary and important [2]. Recent studieshave shown that surface modification with metal nanoparticles exhibit good synergetic effect onH2O2 reduction.Because of the unique properties of porous silicon (PSi) such as high specific surface area, hightendency for oxidation/reduction reaction and capability for surface functionalization, it waschosen suitable substrate for decoration of metal nanoparticles. PSi is a porous medium, whichcan be easily produced by chemical etching of silicon in HF solution [3]. PSi has manyapplications in the field of chemical sensors and biosensors [4].In this work, a porous silicon/silver nanocomposite was prepared and used as a modifier incarbon paste electrode, as an electrochemical sensor for the determination of hydrogen peroxide(H2O2). By using a simple and fast galvanic replacement reaction between Si atoms in the poroussilicon and silver cation in aqueous HF solution, silver nanoparticles were decorated on theporous silicon without using any reducing agent. This novel nanocomposite was characterized bymeans of X-ray diffraction, scanning electron microscopy, Fourier transform infraredspectroscopy and cyclic voltammetry. The modified car-bon paste electrode was used to study thereduction of H2O2 in 0.1 mol L−1phosphate buffer solution (pH 7.0). Moreover,chronoamperometery was used for determination of H2O2at the applied potential of −0.45 V (vs. Ag/AgCl). The sensor has a linear response range of 1.65 L−1 -0.5 mmol L−1with adetection limit of 0.45 L−1 H2O2. The electrochemical sensor showed fast and selectiveresponses to H2O2 concentration. The applicability of the sensor was checked using real sampleswith satisfactory results.

Keywords:

Hydrogen peroxide detection , Porous silicon/silver nanocomposite , synergetic effect , electrochemical sensor , Amperometry