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

Sensitive and selective determination of H2O2 is of great significance in biological, clinical and environmental and many other fields. Among several analytical techniques that have been employed for the determination of H2O2, electrochemical methods have received significant importance due to their low detections limit, high selectivity and sensitivity [1]. Because electrochemical reduction of H2O2 with the conventional electrodes is not effective for analytical application, surface modification of the electrode is necessary and important [2]. Recent studies have shown that surface modification with metal nanoparticles exhibit good synergetic effect on H2O2 reduction. Because of the unique properties of porous silicon (PSi) such as high specific surface area, high tendency for oxidation/reduction reaction and capability for surface functionalization, it was chosen suitable substrate for decoration of metal nanoparticles. PSi is a porous medium, which can be easily produced by chemical etching of silicon in HF solution [3]. PSi has many applications in the field of chemical sensors and biosensors [4]. In this work, a porous silicon/silver nanocomposite was prepared and used as a modifier in carbon 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 porous silicon and silver cation in aqueous HF solution, silver nanoparticles were decorated on the porous silicon without using any reducing agent. This novel nanocomposite was characterized by means of X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and cyclic voltammetry. The modified car-bon paste electrode was used to study the reduction 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. 255 Ag/AgCl). The sensor has a linear response range of 1.65 μmol L−1 -0.5 mmol L−1with a detection limit of 0.45 μmol L−1 H2O2. The electrochemical sensor showed fast and selective responses to H2O2 concentration. The applicability of the sensor was checked using real samples with satisfactory results.