Pd-NWs ordered arrays for electrochemical sensing of H2O2

Abstract

In this work, we present the performance of nanostructured array of Pd (Pd-NWs) for electrochemical sensors of hydrogen peroxide. Hydrogen peroxide is widely used in several fields, because to its oxidizing and reducing properties, like for treatment of waste water, paper and contaminated soils, as reagent in many chemical industries or like rocket propellant [1]. Furthermore, its presence or absence may be connected with many neurological deseases or/and with cancer [2].Today the most used methods for detection of that chemical are IR spectroscopy, spectrophotometry, fluorimetry, chemioluminescence and redox titration. However these methods are often uneconomical, have very high detection time or requires highly skilled staff [3]. On the other hand electrochemical tequiniques are very cheap, have a response time less than 5 seconds and not require any qualified staff. The electrochemical reduction of H2O2 on the electrode surfaces requires the absorption of a hydroxyl group on the surface of the sensor [4], consequently, performance of the sensor will be improved by a greater electrochemical active area. Thus, the use of nanostructures, such as nanowires, nanotubes or nanoparticles, allows to improve considerably the performance of the sensor because of their very high surface area, that is 70 times grater than geometric one. Most studies about electrochemical sensing of H2O2 have examined biological materials like protein or enzymes but, despite being highly selective, these biosensors have a very short lifetime and so are therefore uninteresting [3]. Most of the scientific research in this area is focused on transition metals or metal oxide and in particular on metal/metal oxide nanostructure, like nanoparticles, nanowire and nanotubes [5]. Guangdi Nie et al [6] has shown that Pd nanoparticles exhibit very good catalytic proprieties and stability towars H2O2 reduction. For this reason here we describe a simple, fast and cheap method for the detection of H2O2 based on an ordered arrays of Pd nanowire that exhibit a very large area respect Pd nanoparticles and so it should show higher electrocatalytic properties. Nanostructured sensors are obtained by template synthesis in commercial polycarbonate membranes. Arrays of Pd nanowires were fabricated through a displacement deposition reaction that permits to obtain nanostructures directly, very stable mechanically, and without the use of an external power supply. The morphology and the composition of Pd-NWs was monitored by SEM and energy-dispersive X-ray spectroscopy (EDX). The electrochemical properties of these sensors were characterized by ciclicvoltammetry and cronoamperometry. To test the performance of nanostructured sensors, electrochemical experiments were carried out in an aqueous solution with different amounts of hydrogen peroxide. In order to obtain sensors with stable performance, we found that it is essential to increase wettability of the nanostructures through addition of pure ethanol to the test solution. These electrodes showed a stable and sensitive response towards H2O2 with a wide linear dependence over H2O2 concentration from 50 μM to 4400 μM and LOD of 15 μM and a good stability, greater than 1 month. These results imply thant the proposed electrodes could be successfully used as electrochemical sensor for hydrogen peroxide. [1]A nonenzymatic hydrogen peroxide sensor based on Au–Ag nanotubes and chitosan film ; Xueqin Li, Lisha Wang, Qi Wu,Zhichun Chen, Xianfu Lin [2] Silver nanowire array sensor for sensitive and rapid detection of H2O2E. Kurowska, A. Brz ́ozka, M. Jarosz, G.D. Sulka, M. Jaskuła [3] Elettrodi modificati per lo sviluppo di sensori elettrochimici, Università degli Studi di Bologna, Facoltà di Chimica Industriale, Lorella Guadagnini, Giuliano Longoni, Domenica Tonelli [4] Carbon nanodots as reductant and stabilizer for one-pot sonochemical synthesis of amorphous carbon-supported silver nan